WO2014151861A1 - Multivalence photocatalytic heterogeneous materials for semiconductors - Google Patents

Abstract

Described herein are heterogeneous materials comprising a p-type semiconductor comprising two metal oxide compounds of the same metal in two different oxidation states and an n-type semiconductor having a deeper valence band than the p-type semiconductor valence bands wherein the semiconductor types are in ionic communication with each other. The heterogeneous materials enhance photocatalytic activity.

Description

MULTIVALENCE PHOTOCATALYTIC HETEROGENEOUS MATERIALS FOR

SEMICONDUCTORS

Inventors:

Ekambaram Sambandan and Bin Zhang

FIELD OF THE DISCLOSURE

[001] The current disclosure describes heterogeneous materials having a p-type semiconductor comprising mixed valence oxide compounds and an n-type semiconductor having a deeper valence band than that of the p-type semiconductor, the n-type semiconductor in ionic charge communication with the mixed valence oxide compounds of the p-type semiconductor. These multivalent heterogeneous materials can be used to enhance the photocatalytic activity of photocatalytic materials.

BACKGROUND OF THE DISCLOSURE

[002] Visible light activated photocatalysts can be deployed for self-cleaning, air and water purification and many other interesting applications usually without any post- deployment non-renewable energy costs. This is because the photocatalysts are able to decompose pollutants (like dyes, volatile organic compounds and NO_x) using ambient light like solar radiation or indoor and outdoor lighting. With the anticipated rapid adoption of UV- free indoor lighting (like LEDs and OLEDs), it is imperative to find ways to deploy visible-light activated photocatalysts in indoor applications, for instance, in cleaning room air in domestic, public and commercial spaces especially in confined areas like aircraft, public buildings, etc. Moreover, additional applications for antibacterial surfaces and self-cleaning materials can have wide applicability in the food service, transportation, health care and hospitality sectors.

[003] Elemental copper, copper composites, alone or in combination with metal oxides, have been described as useful photocatalytic/antibacterial/antiviral materials. See United States Patent Publication Nos. 2007/0154561 , 2009/0269269, 201 1/0082026, and 2012/0201714; and, Qiu, Xiaoqing et al., "Hybrid Cu_xO/Ti0₂ Nanocomposites as risk- reduction materials in indoor environments," ACS Nano, 6(2): 1609-1618 (2012). Elemental copper however, shows a degradation of antibacterial activity over time (durability) and unappealing cosmetic appearance change (from Cu metal to black CuO) both believed due to oxidation of elemental copper under normal application conditions. Thus, there is a need for improved longevity of anti-bacterial activity over time. Thus there is a need for photocatalytic materials that provide antibacterial/antiviral activity without unappealing cosmetic appearance changes. SUMMARY OF THE DISCLOSURE

[004] The current disclosure describes heterogeneous materials having a p-type semiconductor comprising mixed valence oxide compounds and an n-type semiconductor having a deeper valence band than that of the p-type semiconductor wherein the semiconductors are in ionic charge communication with each other. These multivalent heterogeneous materials can be used to enhance the photocatalytic activity of photocatalytic materials and to improve durability (i.e. maintain photocatalytic activity over time). Photocatalytic materials are useful for having and/or enhancing anti-bacterial (light and dark) activity, anti-viral activity, decomposition of volatile organic compounds (VOC) and/or dye discoloration in aqueous solutions.

[005] Some embodiments include a heterogeneous material comprising: a p-type semiconductor comprising a first metal oxide compound and a second metal oxide compound, wherein the first metal oxide compound and the second metal oxide compound have different oxidation states of the same metal, and wherein the p-type semiconductor has a p-type valence band; and an n-type semiconductor having an n-type valence band which is deeper than the p-type valence band, wherein the n-type semiconductor is in ionic charge communication with the p-type semiconductor.

[006] Another embodiment further comprises a noble metal in ionic charge communication with the mixed valence oxide compounds. In another embodiment, the noble metal is rhodium, ruthenium, palladium, silver, osmium, platinum or gold. In another embodiment the noble metal is loaded onto the n-type semiconductor.

[007] Another embodiment further comprises a second n-type semiconductor, wherein at least a portion of the second n-type semiconductor is ionic charge isolated from the mixed valence oxide compounds In another embodiment, the second n-type semiconductor comprises a cerium oxide. In another embodiment, the cerium oxide is Ce0₂. In another embodiment, the second n-type semiconductor comprises plural phase T1O2.

[008] In another embodiment, the mixed valence oxide compounds comprise a pair of the same metallic chemical element, e.g. Cu, Co, Mn, Fe, Ir, etc., in two different oxidation states, such as the pairs copper(l) and copper(ll); cobalt (II) and cobalt (III); Mn(ll) and Mn(lll); Fe(ll) and Fe(lll); or, Ir(lll) and Ir(IV).

[009] In another embodiment, the p-type semiconductor is loaded onto the n-type semiconductor.

[010] In another embodiment, the p-type semiconductors are substantially uniformly dispersed onto the n-type semiconductor. In another embodiment, the mixed valence oxide compounds have a particle size of 100 nm or less. [011 ] In another embodiment, the copper(l) and copper (II) compound is a Cu_xO compound. In another embodiment, the Cu_xO compound is chemically valence controlled. In another embodiment, the ratio of copper(l):copper (II) is between 10:90 to 90:10.

[012] In another embodiment, the p-type semiconductor is 0.001 to 10 wt% of the heterogeneous material and the p-type semiconductor is 90 to 99.999 wt% of the heterogeneous material.

[013] The n-type semiconductor can be any suitable semiconductor wherein the charge carriers are electrons, such as electrons in the conduction band which are donated from a donor band of a dopant. In another embodiment, the n-type semiconductor is an oxide comprising cerium, tungsten, tantalum, tin, zinc, strontium, zirconium, barium, indium or aluminum oxide. In another embodiment, the n-type semiconductor is Sn-Ti(0,C,N)₂, Ce0₂, KTa0₃, Ta₂0₅, Sn0₂, W0₃, ZnO, SrTi0₃, BaTi0₃, ZrTi0₄, ln₂Ti0₅, AI₂Ti0₅, or LiCa₂Zn₂V₃0i₂. In another embodiment, the n-type semiconductor is Sn-Ti(0,C,N)₂ In another embodiment, the n-type semiconductor is AI₂._xln_xTi0₅ wherein 0<x<2. In another embodiment, the n-type semiconductor is Zr₁._yCe_yTi0₄ wherein 0<y<1.

[014] In another embodiment, the n-type semiconductor can comprise an oxide comprising titanium. In another embodiment, the oxide comprising titanium comprises a plural phase titanium oxide. In another embodiment, the plural phase titanium oxide comprises a mixture of anatase Ti0₂ phase and rutile Ti0₂ phase.

[015] In another embodiment, the n-type semiconductor is a titanium oxide having a dopant. For example, a dopant could donate electrons to the conducting band of titanium oxide. In another embodiment, the n-type semiconductor is a titanium oxide doped with N, C, or both. In another embodiment, the n-type semiconductor is a titanium oxide comprising a compound represented by the formula (Ti^_rM_r)(0₂-_s-_tC_sN_t), wherein: M is Sn, Ni, Sr, Ba, Fe, Bi, V, Mo, W, Zn, or Cu, or combinations thereof; r is in the range of 0 to 0.25; s is in the range of 0.001 to 0.1 ; and, t is in the range of 0.001 to 0.1.

[016] Another embodiment comprises a photocatalyst (Tio_.99Sn₀.oi)(0₂._s.tC_sNt), (Tio_.97Sn_{0 3})(0₂_s_tC_sN_t), (Tio.9₅Sno.o5)(0₂__s_tC_sN_t), (Tio.9oSn₀.io)(0₂__s_tC_sN_t), (Tio.85Sno.i₅)(0₂__s_tC_sN_t),

(Tio.985Nio.oi5)(0₂-s-tC_sNt), (Ti₀.98Nio.o2)(0₂-s-tC_sNt), (Tio.9₇Nio.o3)(0₂-s-tCsNt), (Tio.99Sr₀.oi)(0₂-_s- _tCsNt), (Tio.9₇Sro.o₃)(0₂__s__tCsNt), (Tio.9₅Sro.o5)(0₂__s_tC_sN_t), (Tio.9₇Bao.o₃)(0₂__s_tC_sN_t),

(Tio.9₅Bao.o5)(0₂._s.tC_sNt), (Tio.9₄Sno.o5Feo.oi)(0₂._s.tC_sNt), (Tio.94Sno.o₅Nio.oi)(0₂__s_tC_sNt),

(Tio_.99Fe₀.oi)(0₂__s_tC_sNt), (Tio.9₅Zno.o5)(0₂__s_tC_sNt), (Tio.₇₇Sno.i₅Cuo.o8)(0₂._s.tC_sNt), (Ti₀.85Zno.i₅)(0₂._s. tCsNt), (Tio.9oBio.io)(0₂__s_tC_sN_t), (Tio.99₆Vo.oo4)(0₂__s__tCsNt), (Ti₀.984Vo.oi6)(0₂__s__tCsNt),

(Tio.9₇oVo.₀₃)(0₂__s_tCsNt), (Tio.99₇Moo.oo3)(0₂__s_tC_sN_t), (Tio.984MOo.oi6)(0₂__s_tC_sN_t), (Ti₀.95₇Mo₀.043)(O₂. s_tC_sN_t), (Tio.9₇Wo_.03)(0₂__s_tC_sN_t), (Tio.95VVo.o5)(0₂__s_tC_sN_t), (Tio.99₆Vo.oo4)(0₂__s_tC_sN_t),

(Tio.984Vo.oi6)(0₂__s_tC_sN_t) or (Ti₀.9₇oVo.o₃)(0₂._s.tC_sN_t). [017] Some embodiments include a method of decomposing a chemical compound, comprising exposing the chemical compound to a photocatalyst comprising a homogeneous material described herein in the presence of light. In some embodiments, the chemical compound is a pollutant, such as a volatile organic compound.

[018] Some embodiments include a method of killing a microbe, comprising exposing the microbe to a photocatalyst comprising a homogeneous material described herein in the presence of light.

[019] A particular embodiment as described herein includes a method for loading a mixed valence compound. This method can include adding a dispersing agent to a mixed valence- type compound to more positively charge the surface of the n-type compound; adding an attracting agent to the n-type compounds to make the surface charge of the n-type semiconductor more negative; and, mixing the dissimilarly charged materials with each other at a temperature below the doping temperature of the mixed valence compound.

BRIEF DESCRIPTION OF THE DRAWINGS

[020] FIG. 1A is a schematic showing the relationship between conduction energy bands with valence energy bands for metal materials.

[021] FIG. 1 B is a schematic showing the relationship between conduction energy bands with valence energy bands for semi-conductor materials.

[0010] FIG. 1 C is a schematic showing the relationship between conduction energy bands with valence energy bands for non-conducting materials.

[0011] FIG. 2 is a schematic showing the conduction and valence energy band levels for various compounds described herein.

[0012] FIG. 3 shows the x-ray diffraction patterns of an embodiment of a p-type and n-type composite material described herein with that of the n-type material alone.

[0013] FIG. 4 shows the x-ray diffraction patterns of another embodiment of a p-type and n-type composite material described herein with that of the n-type material alone.

[0014] FIG. 5 shows the x-ray diffraction patterns of another embodiment of a p-type and n-type composite material described herein with that of the n-type material alone.

[0015] FIG. 6 shows the diffuse reflectance spectra comparing embodiments of a p-type and n-type composite material described herein and that of the n-type material alone

(Ti(OCN) ₂:Sn).

[0016] FIG. 7 shows the diffuse reflectance spectra comparing another embodiment of a p- type and n-type composite material described herein that of the n-type material alone (Ce0₂).

[0017] FIG. 8 shows the diffuse reflectance spectra comparing another embodiment of a p- type and n-type composite material described herein that of the n-type material alone. [0018] FIG. 9 is a graph showing the decomposition of acetylaldehyde by various photocatalytic composites, Ex-1A and CE-1 described herein.

[0019] FIG. 10 is a graph showing the antibacterial activity (CFU/Specimen) on E.Coli by various photocatalystic composites, Ex-1A and CE-1 described herein after exposure to visible light of 800 lux from a fluorescent lamp.

[0020] FIG. 1 1 is a graph showing the antibacterial activity (CFU/Specimen) on E.Coli by various photocatalytic composites, Ex-4 and CE-2 described herein after exposure to visible light of 800 lux from a fluorescent lamp.

[0021] Fig.12A is a graph showing the enhanced durability antibacterial activity on E. coli by photocatalytic composites, Ex-1 , before and after being treated at 85° C and 85% relative humidity (RH) for 7 days.

[0022] Fig. 12B is a graph showing the enhanced durability antibacterial activity on E. coli by photocatalytic composites, Ex-7, before and after treated at 300° C for 20 min.

[0023] Fig. 13 is a graph showing the dye discoloration of natural blue color by various photocatalytic composites, Example 1 and CE-1 described herein along with rutile Ti0₂ with and without Cu_xO loading.

[0024] Fig.14 is a graph showing the decomposition of acetaldehyde by various photocatalytic composites, Ex-12, 13, 15, 16 and CE-6 described herein.

[0025] Fig. 15 is a graph showing the dye discoloration of blue dye color by various photocatalytic composites, Example 19 and Sn0₂ without loading.

[0026] Fig. 16 is a graph showing the dye discoloration of natural blue color by various photocatalytic composites, Ex-18.

[0027] Fig. 17 is a graph showing the effect of a physical mixture of CE-0 (0.25 wt.% CuO + 0.12 wt.% Cu₂0 + 0.5 wt.% Sn doped Ti(OCN)₂ photocatalyst) on E. coli killing property.

[0028] Fig. 18 is a graph showing the effect of Ex-7A (0.5 wt.% Cu_xO loaded alumina (non- photocatalyst)) on antibacterial property {E. coli killing study).

[0029] Fig. 19 is a graph showing the effect of Ex- 1 B (0.5 wt.% Cu_xO loaded Sn doped Ti(OCN)2 photocatalyst) on antibacterial property (E. coli killing study).

[0030] Fig. 20 is a graph showing the synergy effect of Ex-1 (1 wt.% Cu_xO loaded Sn doped Ti(OCN)₂) on antibacterial property (E. coli killing study) .

[0031] Fig. 21 is a graph showing the enhanced durability result of Ex-1 (1wt.% Cu_xO loaded Sn doped Ti(OCN)₂) on antibacterial property (E. coli killing study).

[0032] Fig. 22 is a graph showing the synergy effect of Cu_xO/P25 and Cu_xO/AI₂0₃ on antibacterial property (E. coli killing study) .

[0033] Fig. 23 is a graph showing the enhanced durability result of Cu_xO/P25 and Cu_xO/AI₂0₃ on antibacterial property (E. coli killing study). DETAILED DESCRIPTION

[0034] The current disclosure describes heterogeneous materials having a p-type semiconductor comprising a mixed valence oxide compound. The p-type semiconductor has a p-type valence band. The heterogeneous material also comprises an n-type semiconductor having an n-type valence band which is deeper valence band than the p-type valence band. In the heterogeneous material, the n-type semiconductor is in ionic charge communication with the mixed valence oxide compound. These multivalent heterogeneous materials can be used to enhance the photocatalytic activity of photocatalytic materials and to improve durability (i.e. maintain photocatalytic activity over time). Photocatalytic materials are useful for having and/or enhancing anti-bacterial (light and dark) activity, anti-viral activity, decomposition of volatile organic compounds (VOC) and/or dye discoloration in aqueous solutions.

[0035] As shown in FIG. 1 , a conduction band 10 is a range of electron energies enough to free an electron from binding with its atom to move freely within the atomic lattice of the material as a 'delocalized electron'. In semiconductors, the valence band 20 is the highest range of electron energies in which electrons are normally present at absolute zero temperature. The valence electrons are substantially bound to individual atoms, as opposed to conduction electrons (found in semiconductors), which can move more freely within the atomic lattice of the material. On a graph of the electronic band structure of a material, the valence band 20 is generally located below the conduction band, separated from it in insulators and semiconductors by a band gap 30. In some materials, the conduction band has substantially no discernible energy gap separating it from the valence band. The conduction and valence bands may actually overlap (overlap 25), for example, when the valence band level energy is higher or less negative than the conduction band level energy.

[0036] Various materials may be classified by their band gap; e.g., classified by the difference between the valence band 20 and conduction band 10. In non-conductors (e.g., insulators), the conduction band is much higher energy than the valence band, so it takes much too much energy to displace the valence electrons for an insulator to effectively conduct electricity. These insulators are said to have a non-zero band gap. In conductors, such as metals, that have many free electrons under normal circumstances, the conduction band 10 overlaps 25 with the valence band 20 - there is no band gap, so it takes very little or no additional applied energy, to displace the valence electrons. In semiconductors, the band gap is small, on the order of 200 nm to 1000 nm. While intending to be bound by theory, this is believed to be the reason that it takes relatively little energy (in the form of heat or light) to make semiconductors' electrons move from the valence band to another energy level and conduct electricity; hence, the name semiconductor.

[0037] In some embodiments, an heterogeneous material is provided that comprises a p- type semiconductor comprising a mixed valence oxide compound, the compound having a p- type conduction band and a p-type valence band; and, a separate n-type semiconductor having an n-type valence band that is deeper, lower energy, or more negative than the p- type valence band. The n-type semiconductor should be in ionic charge communication with the p-type semiconductor, meaning that ionic charge can be transferred from the n-type semiconductor to the mixed valence oxide compound, or from the mixed valence oxide compound to the n-type semiconductor. Examples of suitable conduction bands and valence bands are shown in FIG. 2. While not intending to be bound by theory, if the valence band of the n-type semiconductor is deeper or more negative than the valence band of the p-type, electrons are more easily able to pass from the n-type to the p-type compound. If the materials are in ionic communication, electrons can pass from one compound to the next, enabling regeneration of the higher valence compound to the lower valence compound. For example, Cu²⁺ can be recycled to Cu¹⁺ via this mechanism. In some embodiments, the materials in ionic communication are loaded onto one another. By loading, the materials retain their separate identity; e.g., Cu_xO (p-type semiconductor) separate from ΤΊΟ_2,, Ti(OCN)₂:Sn, etc. (n-type semiconductor). In particular embodiments, one material is on the surface, in contact with or in close proximity to the other, as opposed to doping, physically separated from the other, ionic charge isolated or admixing (physical mixing). In some embodiments, such contact and/or isolation can be determined by transmission electron microscopy (TEM) examination of the p-type and n-type materials. In other embodiments, the heterogeneous materials are integrated within a compound matrix; e.g., incorporated into the compound/crystal lattice.

[0038] A heterogeneous material may comprise any suitable p-type semiconductor, including any semiconductor wherein the charge carrier is effectively positive holes. These holes may be present in a p-type valence band, which can be essentially full of electrons, except for a few holes which may essentially carry the positive charge. In some embodiments, a p-type semiconductor may comprise a mixed valence oxide compound having a p-type valence band. In some embodiments, the mixed valence oxide compounds comprise a mixed valence pair of the same metallic element, such as copper(l) and copper(ll); cobalt (II) and cobalt (III); Mn(ll) and Mn(lll); Fe(ll) and Fe(lll); and/or, Ir(lll) and Ir(IV); and, combinations thereof. In particular embodiments, copper (I) and copper (II) compounds can be Cu_xO compounds. In particular embodiments, the mixed valence oxide compounds can include Cu¹⁺ and Cu²⁺. Ratios of mixed valence oxide compounds can be 10% to 90% to 90% to 10%. Particular ratios can also include: 15% to 85%; 20% to 80%; 25% to 75%; 30% to 70%; 35% to 65%; 40% to 60%; 45% to 55%; 50% to 50%; 55% to 45%; 60% to 40%; 65% to 35%; 70% to 30%; 75% to 25%; 80% to 20%; and 85% to 15%.

[0039] In a particular embodiment, the mixed valence metal oxide compounds are Cu^{1 +}:Cu²⁺ at a ratio of 10% to 90% Cu^{1 +} to 90% to 10% Cu²⁺. The ratio of Cu^{1 +}:Cu²⁺ can also be about 10%:90% to about 30%:70%, about 15%:85% to about 25%:75%, about 15%:85%; about 20%:80%; about 25%:75%; about 30%:70%; about 35%:65%; about 40%:60%; about 45%:55%; about 50%:50%; about 55%:45%; about 60%:40%; about 65%:35%; about 70%:30%; about 75%:25%; about 80%:20%; or about 85%: 15%. In some embodiments the ratios are Cu^{1 +}:Cu²⁺ wt%. In some embodiments the ratios are Cu^{1 +}:Cu²⁺ molar%.

[0040] In some embodiments, wherein the n-type semiconductor in ionic charge communication with the p-type semiconductor, the p-type semiconductor is loaded onto the n-type semiconductor. In some embodiments, wherein the n-type semiconductor in ionic charge communication with the p-type semiconductor, the p-type semiconductor can be embedded, layered, in contact with and/or deposited onto the n-type semiconductor. In some embodiments, the p-type semiconductor mixed valence compounds are substantially uniformly dispersed onto the n-type semiconductor. The particle size of the mixed valence compounds can be less than 200 nm; less than 190 nm; less than 180 nm; less than 170 nm; less than 160 nm; less than 150 nm; less than 140 nm; less than 130 nm; less than 120 nm; less than 1 10 nm; less than 100 nm; less than 90 nm; less than 80 nm; less than 70 nm; less than 60 nm; less than 50 nm; less than 40 nm; less than 30 nm; less than 20 nm; or, less than 10 nm. In a particular embodiment, the particle size of the mixed valence compounds is 100 nm or less.

[0041] In some embodiments, the p-type semiconductor comprises from 0.001 to 10 wt% of the heterogeneous material and the n-type semiconductor comprises from 99.999 to 90 wt% of the heterogeneous material. In additional embodiments, the p-type semiconductor comprises 0.001 wt% of the heterogeneous material; 0.005 wt% of the heterogeneous material; 0.01 wt% of the heterogeneous material; 0.05 wt% of the heterogeneous material; 0.1 wt% of the heterogeneous material; 0.5 wt% of the heterogeneous material; 1 wt% of the heterogeneous material; 2 wt% of the heterogeneous material; 3 wt% of the heterogeneous material; 4 wt% of the heterogeneous material; 5 wt% of the heterogeneous material; 6 wt% of the heterogeneous material; 7 wt% of the heterogeneous material; 8 wt% of the heterogeneous material; 9 wt% of the heterogeneous material; or, 10 wt% of the heterogeneous material. In additional embodiments, the n-type semiconductor comprises 90 wt% of the heterogeneous material; 91 wt% of the heterogeneous material; 92 wt% of the heterogeneous material; 93 wt% of the heterogeneous material; 94 wt% of the heterogeneous material; 95 wt% of the heterogeneous material; 96 wt% of the heterogeneous material; 97 wt% of the heterogeneous material; 98 wt% of the heterogeneous material; 99 wt% of the heterogeneous material; 99.1 wt% of the heterogeneous material; 99.2 wt% of the heterogeneous material; 99.3 wt% of the heterogeneous material; 99.4 wt% of the heterogeneous material; 99.5 wt% of the heterogeneous material; 99.6 wt% of the heterogeneous material; 99.7 wt% of the heterogeneous material; 99.8 wt% of the heterogeneous material; or, 99.5 wt% of the heterogeneous material.

[0042] In some embodiments, the p-type semiconductor comprises a mixture of copper oxides, such as a first copper oxide compound and a second copper oxide, such as a Cu (I) compound (e.g. Cu₂0) and a Cu (II) compound (e.g. CuO). In some embodiments, the p- type semiconductor comprises Cu (I) (e.g. Cu₂0) and Cu (II) (e.g. CuO) in a weight:weight or a mole:mole ratio [Cu (l):Cu (II)] of about 1 :9 to about 3:7, about 1 :3 to about 1 :6, or about 1 :3 to about 1 :4.

[0043] Some embodiments include a p-type semiconductor of the previous paragraph in combination with a n-type semiconductor that is a titanium oxide or Ti(0,C,N)₂ doped with tin, or a titanium oxide, such as Ti0₂, having more than one phase. In some embodiments, such a Ti0₂ can have two phases, such as rutile Ti0₂ and anatase Ti0₂. In some embodiments, the n-type semiconductor can be about 70% to about 90% anatase phase and 10% to about 30% rutile phase Ti0₂, about 80% to about 90% anatase phase and 20% to about 30% rutile phase Ti0₂, about 75% to about 80% anatase phase and 15% to about 20% rutile phase Ti0₂, or about 83% anatase phase Ti0₂ and 17% rutile phase Ti0₂. Some embodiments include a p-type semiconductor of the previous paragraph in combination with a n-type semiconductor that is tin oxide.

[0044] With respect to a semiconductor comprising a p-type semiconductor having a mixture of copper oxides and an n-type semiconductor that is a titanium oxide or Ti(0,C,N)₂ doped with tin, or a titanium oxide, such as Ti0₂, having more than one phase, in some embodiments, the copper oxides may be about 0.1 % to about 5%, about 0.2% to about 2%, about 0.2% to about 1.5%, about 0.5%, or about 1 % of the total weight of the n- and p-type semiconductors.

[0045] In some embodiments, the p-type semiconductor is loaded onto the n-type semiconductor. In some embodiments, the n-type semiconductor is an oxide comprising an element that can be cerium, tungsten, tantalum, tin, zinc, strontium, zirconium, barium, indium, or aluminum oxide having a valence band deeper than that of the p-type semiconductor pair valence bands. In some embodiments, the n-type semiconductor can be anatase, rutile, wurtzite, spinel, perovskite, pyrochlore, garnet, zircon and/or tialite phase material or mixtures thereof. Each of these options is given its ordinary meaning as understood by one having ordinary skill in the semiconductor art. Comparison of an x-ray diffraction pattern of a given standard and the produced sample is one of a number of methods that may be used to determine whether the sample comprises a particular phase. Exemplary standards include those XRD spectra provided by the National Institute of Standards and Technology (NIST) (Gaitherburg, Maryland, USA) and/or the International Centre for Diffraction Data (ICDD, formerly the Joint Committee on Powder Diffraction Standards [JCPDS]) (Newtown Square, Pennsylvania, USA). In some embodiments, the perovskite can be a perovskite oxide. In some embodiments, the perovskite oxide can comprise FeTi0₃, YFe0₃, LuRh0₃, BaSn0₃, Ba₀.8Ca₀.₂TiO₃, CdSn0₃, LaRh0₃, LaRh0₃, LaMn0_3, CoTi0_3, CuTi0_3, MgTi0_3, ZnTi0_3, BiNbi_-xTa_x0₄, where x = 0 to 1 .00, or lnNbi_-xTax0₄, where x = 0 to 1 .00.

[0046] In additional embodiments, the n-type semiconductor can comprise cerium, tungsten, tantalum, tin, zinc, strontium, zirconium, barium, indium, niobium, vanadium, iron, cadmium, germanium and/or aluminum oxide. The n-type semiconductor can also comprise Ce0₂; MgTa₂0₆; BaTa₂0₆; SrTa₂0₆; Ta₂0_5; FeTa₂0₆; Hg₂Ta₂0₇; Hg₂Nb₂0₇; Hg₂Ta_vNbi_-v0₇; K₃Ta₃Si₂0₁₃; K₂LnTa₅0₁₅; W0₃; ZnO; SrTi0₃; SrNb₂0₇; SrTa₂0₇; SrTaNb0₇; Sr₂FeNb0₆; Sr₃FeNb₂0₉; Ti0₂; Sn0₂; BaTi0₃; FeTi0₃; CdFe₂0₄; MnTi0₃; Cs₂Nb₄0n ; KNb0₃; Sr₂FeNb0₆; Sr₃FeNb₂0₉; NiNb₂0₆; CoNb₂0₆; ZnNb₂0₆; Nb₂0₅; K₄Nb₆0₁₇; Rb₄Nb₆0₁₇; CuTi0₃; Bi0₃; ln₂0₃; LiTa0₃; NiTi0₃; ln₂Ti0_5; AI₂Ti0₅; AI₂._xln_xTi0₅; ZrTi0_4; Zr₁._yCe_yTi0₄; LiCa₂Zn₂V₃0i₂; Cd₂Sn0₄; Cdln₂0₄; Cd₂Ge0₄; Bi₂W₂0₉; Bi₂W0₆; Bi₃TiNb0₉; ACr0₄, wherein A can be Sr, Ba or combination of them; CuMn0₂; PbW0₄; CuFe0₂; lnV0₄; MVW0₆, wherein M can be Li, Ag or combination of them; Bi₂MNb0₇, wherein M can be Al, Ga, In, Y, Rare earth, Fe or combination of them; Zr₂W0₆; PbW0₄; SnW0₄; Bi₂W₂0₉; Na₂W₄0i₃; and/or, MW0 , wherein M can be Ca, Zn, Cu or combination of them.

[0047] In some embodiments, the n-type semiconductor can be a vanadium garnet semiconducting photocatalyst. In some embodiments, the vanadium garnet semiconducting photocatalyst can be represented by the formula: (Ai_-xO_x)3(M)2(V₃)Oi2, wherein 0<x<1 . In some embodiments, the cumulative ionic charge of (Ai__xO_x)₃ and (M)₂ is +9. In some embodiments, A⁺ can be Li⁺, Cu⁺, Na⁺, K⁺, Ti⁺, Cd²⁺, Ca²⁺, Sr²*, Pb²⁺, Y³⁺, Bi³⁺, Ln³⁺, or combinations thereof. In some embodiments, M can be one or any of Li⁺, Ni²⁺, Mg²⁺, Co²⁺, Cu²⁺, Zn²⁺, Mn²⁺, Cd²⁺ , Cr³⁺, Fe³⁺, or Sc³⁺ or combinations thereof.

[0048] In some embodiments, the n-type semiconductor can be a vanadium garnet semiconducting photocatalyst. In some embodiments, the vanadium garnet semiconducting photocatalyst can be represented by Formula 1 : (A²⁺)₃(M⁺M²⁺)(V₃)Oi₂. In some embodiments, the vanadium garnet semiconducting photocatalyst can be Ca₃LiZnV₃0i₂ and/or Sr₃LiZnV₃0i₂.

[0049] In some embodiments, the n-type semiconductor can be a mixed titanate. The term "mixed titanate" refers to a compound that comprises Ti, O and at least another element; e.g., Ca, Cu, Mg, or La. In some embodiments, the mixed titanate can be CaCu₂Ti₃0i₂ (perovskite titanate); MgTi₂0₅ (pseudobrookite); and/or, La₂Ti₂0₇ (pyrochlore titanate). In some embodiments, the Ti oxide can comprise a mixture of anatase and rutile Ti0₂.

[0050] In some embodiments, the n-type semiconductor can comprise a mixed copper oxide. Mixed copper oxide refers to an n-type semiconductor comprising Cu, O and another element different from copper and oxygen. In some embodiments, the mixed Cu oxide can be CuMn0₂ or CuFe0₂.

[0051] In some embodiments, the n-type semiconductor can be a simple or mixed ferrite. In some embodiments, the mixed ferrite can be Alpha-Fe₂0_3; MFe₂04, where M is Mg, Zn, Ca, Ba or combination of them; Ca₂Fe₂0_5, MFei₂0i₉, where M is Sr, Ba or combination of them; Sr₇Fei₀O_22, MFe0_2.5+x, where M is Sr, Ba or combination of them, Sr₃Fe₂0₆.i6_; Bii.5Pbo.₅Sr₂BiFe₂C>9.₂5; Pb₂Sr₂BiFe₂0_9+y; Bi₂Sr₂BiFe₂0_9+y; and/or, Bi₁.₅Pbo.5Sr₄Fe20₁o.o4.

[0052] In some embodiments the n-type semiconductor can be a Cu_xO loaded oxynitride semiconducting photocatalyst. In some embodiments the oxynitride semiconducting photocatalyst can comprise TaON; MTa0₂N, wherein M is Ca, Sr, Ba or combination of them; SrNb₂0₇-_xN_x; (Gai_-xZn_x)(Ni_-xO_x); and/or (Zn_1+xGe)(N₂O_x).

[0053] In some embodiments the n-type semiconductor can be a Cu_xO loaded sulfide, selenide or sulfoselenide semiconducting photocatalyst. In some embodiments, the sulfide, selenide or sulfoselenide semiconducting photocatalyst can comprise Cd(S_y,Sei-_y), wherein 0<y<1 ; (Cd,Zn(S_y,Sei-_y), wherein 0<y<1 ; (Agln)_xZn₂₍₁._x)(S_y,Sei._y)₂, wherein 0<y<1 ; (Culn)_xZn₂₍i__x)(S_y,Sei-_y)₂, wherein 0<y<1 ; (CuAgln)_xSn₂₍i__x)(S_y,Sei-_y)₂, wherein 0<y<1 ; and/or, Sm₂Ti₂S₂0₅.

[0054] In particular embodiments, the n-type semiconductor comprises a compound represented by the formula AI₂._xln_xTi0₅, wherein x is in the range of 0 to 2 (0<x<2). In other particular embodiments, the n-type semiconductor comprises a compound represented by the formula Zr₁._yCe_yTi0₄, wherein y is in the range of 0 to 1 (0<y<1 ). In particular embodiments, the n-type semiconductor is a titanium oxide having a valence band controlled through doping. In some embodiments, the n-type semiconductor is a titanium oxide doped with N or C or both. In some embodiments, the titanium oxide comprises a compound represented by the formula (Tii__rM_r)(0₂-_s-_tC_sN_t), wherein M is Sn, Ni, Sr, Ba, Fe, Bi, V, Mo, W, Zn, Cu or combinations thereof; r is in the range of 0 to 0.25; s is in the range of 0.001 to 0.1 ; and, t is in the range of 0.001 to 0.1. In some embodiments, r is no more than 0.20. In some embodiments, r can more particularly be 0; 0.01 ; 0.02; 0.03; 0.04; 0.05; 0.06; 0.07; 0.08; 0.09; 0.10; 0.1 1 ; 0.12; 0.13; 0.14; 0.15; 0.16; 0.17; 0.18; 0.19; 0.20; 0.21 ; 0.22; 0.23; 0.24; or 0.25. In some embodiments, s can more particularly be 0.001 ; 0.005; 0.01 ; 0.02; 0.03; 0.04; 0.05; 0.06; 0.07; 0.08; 0.09; or 0.1 . In some embodiments, t can more particularly be 0.001 ; 0.005; 0.01 ; 0.02; 0.03; 0.04; 0.05; 0.06; 0.07; 0.08; 0.09; or, 0.1 .

[0055] The materials are also described in co-pending and co-assigned application, Ser. No. 13/741 , 191 , filed 14-January, 2013, which is incorporated by reference in its entirety for its description of photocatalytic compounds and/or compositions. In some embodiments, M is Sn, Ni, Sr, Ba, Fe, Bi, or combinations thereof. In some embodiments, r is in the range of 0.0001 to 0.15. In some embodiments, M is Sn. In some embodiments, r is at least 0.001 . In some embodiments, the n-type semiconductor comprises (Ti₀.99Sno.oi )(0₂-_s-_tCsNt), (Tio.97Sno.o3)(0₂-s-tC_sNt), (Tio.9₅Sno.o5)(0₂__s_tC_sNt), (Tio.9oSno.io)(0₂-s-tC_sNt), (Tio.8₅Sno.i5)(0₂__s_ tC_sN_t), (Tio.985Nio.oi5)(0₂-s-tC_sNt), (Tio.9₈Nio.o₂)(0₂__s_tC_sNt), (Tio.9₇Nio.o3)(0₂__s_tC_sNt), (Ti₀.99Sr₀.oi )(0₂. s_tC_sN_t), (Tio.9₇Sro.o3)(0₂__s_tC_sN_t), (Tio.9₅Sro.o5)(0₂__s_tC_sN_t), (Tio.9₇Bao.o3)(0₂__s_tC_sN_t), (Tio.9₅Bao.o5)(0₂._s.tC_sNt), (Tio.9₄Sno.o5Feo.oi)(0₂._s.tC_sNt), (Tio.9₄Sno.o5Nio.oi )(0₂._s.tC_sNt), (Tio.99Feo.oi)(0₂-s-tC_sNt), (Ti₀.95Zno.o5)(0₂-s-tC_sNt), (Ti₀.77Sno.i5Cuo.o8)(0₂-s-tCsN_t), (Ti₀.85Zn₀.i5)(O₂-s- tC_sN_t), (Tio.9oBio.io)(0₂__s_tC_sN_t), (Tio.99₆Vo.oo4)(0₂__s_tC_sNt), (Ti₀.984Vo.oi6)(0₂._s.tC_sN_t), (Tio.₉₇oVo.o3)(0₂. s-tC_sNt), (Tio.99₇Moo.oo3)(0₂._s.tC_sNt), (Ti₀.984MOo.oi6)(0₂._s.tC_sN_t), (Ti₀.957MOo.o43)(0₂._s.tC_sN_t), (Tio.97Wo.o3)(0₂-s-tC_sNt), and/or (Ti₀.95Wo.o5)(0₂-s-tCsN_t). In some embodiments, the n-type semiconductor comprises (Tio.996Vo.oo4)(0₂._s._tC_sNt), (Ti₀.984Vo.oi6)(o2-s-tC_sN_t), and/or (Tio.97oVo.o₃)(0₂__s_tC_sNt).

[0056] In some embodiments, wherein the heterogeneous material comprises a p-type semiconductors loaded onto an n-type semiconductor, the heterogeneous material further comprises a second n-type semiconductor, wherein at least a portion of the second n-type semiconductor is ionic charge isolated from the p-type semiconductor. In some embodiments, at least a portion of the second n-type semiconductor can be physically separated from the p-type semiconductor, ionic charge isolated, admixed and/or not loaded with the p-type semiconductor. In some embodiments, the second n-type semiconductor can be any of those n-type semiconductors described elsewhere in this application. In some embodiments, the ionic charge isolated or admixed n-type semiconductor can comprise Ce0₂ and/or plural phase n-type semi-conductor compounds. In some embodiments, the plural phase n-type semi-conductor compounds comprise anatase phase and rutile phase compounds. In some embodiments, the plural phase n-type semiconductor compounds can be titanium oxides. In some embodiments, the anatase phase can be 2.5% to about 97.5%, 5% to about 95%, and/or about 10% to about 90%; and the rutile phase can be 97.5% to about 2.5%, 95% to about 5%, and/or about 10% to about 90%. A non-limiting example of a suitable material includes, but is not limited to a Ti0₂ mixture sold under the brand name P25 (83% Anatase phase Ti0₂ + 17% Rutile phase Ti0₂) sold by Evonik. In some embodiments, the n-type semiconductor physically mixed with p-type loaded on WO3 can comprise Ce0₂, Ti0₂, SrTi0₃ and/or KTa0₃. In some embodiments, the n-type semiconductor physically mixed with p-type loaded on plural phase n-type semi-conductor compounds (e.g., P25) can comprise unloaded plural phase n-type semi-conductor compounds (e.g., P25). In some embodiments, the n-type semiconductor physically mixed with p-type loaded on plural phase n-type semi-conductor compounds can comprise Ce0₂, Ti0₂, SrTi0₃ and/or KTa0₃. In some embodiments, the n-type semiconductor can be inorganic. In some embodiments, the inorganic n-type semiconductor can be an oxide, such as a metal dioxide, including Ce0₂, Ti0₂, or the like. In some embodiments, the n-type semiconductor can comprise Si0₂, Sn0₂, Al₂0₃, Zr0₂, Fe₂0₃, Fe₃0₄, NiO, Nb₂0₅, and/or Ce0₂.

[0057] In some embodiments, the n-type semiconductor can be RE_kE_mO_n, wherein RE is a rare earth element, E is an element or a combination of elements, O is oxygen, and 1 < k < 2, 2 < m < 3, and 0≤ n < 3. In some embodiments, the n-type semiconductor can be RE_pO_q where RE can be a rare earth metal and p can be greater than or equal to 1 and less than or equal to 2, or can be between 1 and 2; and q can be greater than or equal to 2 and less than or equal to 3, or can be between 2 and 3. Examples of suitable rare earth elements include scandium, yttrium and the lanthanide and actinide series elements. Lanthanide elements include elements with atomic numbers 57 through 71. Actinide elements include elements with atomic numbers 89 through 103. In some embodiments, the n-type semiconductor can be Ce_xZr_y0₂ wherein the y/x ratio = 0.001 to 0.999. In some embodiments, the n-type semiconductor can be cerium. In some embodiments, the n-type semiconductor can be CeO_a (a≤ 2). In some embodiments, the n-type semiconductor can be cerium oxide (Ce0₂).

[0058] In some embodiments, the n-type semiconductor can be a non-oxide. In some embodiments, the non-oxide can be a carbide and/or nitride. In some embodiments, the carbide can be silicon carbide.

[0059] In some embodiments, the mole ratio of physical mixture of the n-type semiconductor (e.g., Ce0₂) with p-type semiconductor loaded W0₃ (e.g., Cu_xO-W0₃) can be 0-99% n-type semiconductor to 100%-1 % p-type semiconductor (Cu_xO loaded W0₃). In some embodiments, the mole ratio of physical mixture of the n-type semiconductor (e.g., Ce0₂) with p-type semiconductor loaded W0₃ can be 25 to 75% (and every integer in between) of n-type semiconductor to 75% to 25% (and every integer in between) of p-type semiconductor loaded n-type material (e.g., W0₃). In some embodiments, the mole ratio of physical mixture of the n-type semiconductor (e.g., Ce0₂) with p-type semiconductor loaded W0₃ can be 40 to 60% (and every integer in between) of n-type semiconductor to 60% to 40% (and every integer in between) of p-type semiconductor loaded n-type material (e.g.,

[0060] In some embodiments, the heterogeneous material can further comprise a noble metal in ionic charge communication with the mixed valence oxide compound. In some embodiments, the noble metal is loaded onto the n-type semiconductor. In some embodiments, the noble metal can be, without limitation, rhodium, ruthenium, palladium, silver, osmium, platinum and or gold or mixtures thereof. In one embodiment, the noble metal is platinum.

[0061] In some embodiments a method for loading a mixed valence compound can be adding a p-type precursor to an attracting agent to make the surface charge of the n-type semiconductor more negative, wherein the p-type precursor comprises a copper cation complex. In some embodiments, a method for loading a mixed valence compound comprises adding an attracting agent to the n-type compounds; and combining the n-type and p-type precursors to each other at a temperature below the doping temperature of the mixed valence compounds. In some embodiments the method further comprises the step of adding a dispersing agent to an n-type compound to more positively charge the surface of the n-type compound.

[0062] In some embodiments a method for loading a mixed valence compound can be adding a dispersing agent to an n-type compound to more positively charge the surface of the n-type compound; adding a p-type precursor to the dispersing agent and n-type compound, wherein the p-type precursor comprises a copper cation complex; adding an attracting agent to the n-type compounds to make the surface charge of the n-type semiconductor more negative; and combining the dissimilarly charged materials with each other at a temperature below the doping temperature of the mixed valence compounds.

[0063] In some embodiments, the dispersing agent can be a strong acid. In some embodiments, the dispersing agent can be 4-7M HCI. In some embodiments, the dispersing agent is 6M HCI.

[0064] In some methods, a valence control material is added along with the dissimilarly charged materials to control the mixed valence oxides during the synthesis of the mixed valence oxides. In some embodiments, the valence control material is a mild reducing agent. In some embodiments, the valence control material can be at least one of a sugar, a hydrazide, an amino acid, and/or an amide. In some embodiments, the amide can be urea. In some embodiments, the sugar can be sucrose, fructose, and/or glucose. In some embodiments, the sugar is glucose. In some embodiments, the hydrazide can be Carbohydrazide, Oxalyl Dihydrazide, Maleic Hydrazide, Diformyl Hydrazine or Tetraformyl Trisazine. In some embodiments, the amino acid can be at least one of the proteinogenic or natural amino acids. In some embodiments, the amino acid can be an aliphatic amino acid (e.g., glycine, alanine, valine, leucine, and/or isoleucine). In some embodiments, the amino acid can be a hydroxyl or sulfur containing amino acid (e.g., serine, cysteine, threonine and/or methionine). In some embodiments, the amino acid can be cyclic (e.g., proline). In some embodiments, the amino acid can be aromatic (e.g., phenylalanine, tyrosine and/or tryptophan). In some embodiments, the amino acid can be basic (e.g., histidine, lysine, and/or arginine). In some embodiments, the amino acid is acidic or amide (e.g., aspartate, glutamate, asparagine and/or glutamine). In some embodiments the amino acid can be selenocysteine and/or pyrrolysine. In some embodiments the amino acid can be non- proteinogenic. In some embodiments the non-proteinogenic amino acids include those not found in proteins (for example carnitine, GABA). In some embodiments, the non- proteinogenic amino acids can be those in isolation by standard cellular machinery (for example, hydroxyproline and selenomethionine). In some embodiments, the amino acid is soluble in water. In some embodiments the amino acid is soluble in water at 90°C. In some embodiments the amino acid is substantially entirely dissolved in water at 90°C. The term soluble has the ordinary meaning known to a person of ordinary skill in the art.

[0065] In some embodiments, the ratio of the mixed valence oxide compounds, e.g., Cu^{1 +} compounds and Cu²⁺ compounds, can be controlled by a method of loading the Cu onto the p-type semiconductor including adding the attracting agents. In some embodiments, the attracting agents that can control the ratio of mixed valence oxide compounds can include a monosaccharide and a base compound. In some embodiments, the monosaccharide can be glucose. In some embodiments, the glucose can be D-glucose and/or L-glucose. In some embodiments, the glucose to NaOH ratio can be 10% to 90% to 90% to 10%. Particular ratios can also include: 15% to 85%; 20% to 80%; 25% to 75%; 30% to 70%; 35% to 65%; 40% to 60%; 45% to 55%; 50% to 50%; 55% to 45%; 60% to 40%; 65% to 35%; 70% to 30%; 75% to 25%; 80% to 20%; and 85% to 15%. In some embodiments, the base can be NaOH. Cu_xO compound is valence controlled chemically.

[0066] In some embodiments, the attracting agent can be an agent that provides a sufficient amount of hydroxyl ions to bring the pH of the total solution between pH 8.0 to pH 9.0. In some embodiments, the attracting agent can be a strong base. In some embodiments, the attracting agent is a 4-7 M strong base. In some embodiments, the attracting agent is 6 M NaOH. [0067] In some embodiments, the p-type precursor can be a substantially sodium free compound. In some embodiments, the substantially sodium free compound can be a copper cation complex. In some embodiments, the copper cation complex can be Bis(Ethylenediamine) Copper (II) (BEDCull), Copper (II) tetra amine chloride, Copper (II) tetra amine sulfate, and/or Copper (II) tetra amine hydroxide and/or mixtures thereof. In some embodiments, the compound can be Bis(Ethylenediamine) Copper (II). The structure of BEDCull is shown below:

[0068] In some embodiments, the doping temperature of the mixed valence compound is between 150°C to 700°C. In some embodiments, less than the doping temperature of the mixed valence compound is less than 175°C, less than 150°C, less than 125°C. In some embodiments, the mixing temperature is between 75°C to 125°C. In some embodiments the mixing temperature is 80°C; 85°C; 95°C; 100°C; 105°C; 1 10°C; 1 15°C; 120°C; or, 120°C.

[0069] In some embodiments, the precursor selected for the p-type semiconductors can be salts of chloride, acetate, nitrate, sulfate, carbonate, oxide, hydroxide, peroxide or combinations thereof.

[0070] In some embodiments the described heterogeneous materials have photocatalytic activity. The heterogeneous materials can be anti-bacterial (light and dark); anti-viral; can decompose volatile organic compounds (VOC); and/or can discolor food additive dyes. Suitable non-limiting examples of food additive dyes include Natural Blue Colored powder (Color Maker, Anaheim, California, USA) and/or FD&C blue No. 2 synthetic food additive dye food additive dye (Synthetic blue colored powder, Chromatech, Inc., Michigan, USA). The heterogeneous materials described herein can also increase the durability (time of effectiveness) of photocatalytic materials.

[0071] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material is anti-bacterial (light), e.g., after the heterogeneous material is exposed to visible light. In one embodiment, anti-bacterial exposure results in at least a reduction of 10% (90% remains), at least 50% (50% remains), at least 99% (at least 1 % remains), at least 99.9% (at least 0.1 % remains) or at least 100% (0% remains). One example of determining whether the heterogeneous material is anti-bacterial (light) can be by assessing the amount of bacteria present; e.g., a decrease in the amount of bacteria present, after the heterogeneous material is contacted with the bacteria and exposed to visible light. For example, the amount of bacteria present in the sample after exposing the sample for a predetermined time period can be assessed. In some embodiments, the sample can be exposed for 15 minutes, 30 minutes, 1 hour, 2 hours, 5 hours, 7.5 hours, 10 hours, 12 hours 24 hours. In some embodiments, the sample is exposed to 800 lux from a fluorescent light source or at least 5 mW/cm2 from a blue LED.

[0072] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material is anti-bacterial (dark). In one embodiment, anti-bacterial exposure results in at least a reduction of 10% (90% remains), at least 50% (50% remains), at least 99% (at least 1 % remains), at least 99.9% (at least 0.1 % remains) or at least 100% (0% remains). One example of determining whether the heterogeneous material is anti-bacterial (dark) can be by assessing the amount of bacteria present, e.g., reduction or decrease in the number of colonies present after the heterogeneous material is contacted with the bacteria without exposure to visible light.

[0073] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material is anti-viral. One example of determining whether the heterogeneous material is anti-viral can be by assessing, e.g., an inhibition or reduction of the number of virus (phage) colonies. In one embodiment, determining whether the heterogeneous material is anti-viral can be by counting the number of viral colonies present over time after exposure to the heterogeneous material. In one embodiment, anti-viral exposure results in at least a reduction of 10% (90% remains), at least 50% (50% remains), at least 99% (at least 1 % remains), at least 99.9% (at least 0.1 % remains) or at least 100% (0% remains).

[0074] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material decomposes volatile organic compounds. One example of determining whether the heterogeneous material decomposes volatile organic compounds can be by assessing the degradation of the organic compound under electromagnetic radiation, for example visible light. In one embodiment, determining acetaldehyde degradation as a decrease or % of the initial degradation is an optional way to determine decomposition of volatile organic compounds; e.g., ranging from 0% to 90% over time; or, from 3 to 10 hours or 5 hours under an amount of visible light such as a blue light emitting LED of 455 nm having 270 mW/cm² power. In some embodiments, the degradation is at least 50%, 60%, 70%, 80%, 90% or 100% of the initial amount of acetylaldehyde after exposure to the heterogeneous material.

[0075] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material discolors food additives or dyes. One example of determining the discoloration of food additive dyes can be by the decrease or percentage of the initial amount of food dye additive over time. In one example, the food additive can be the natural anthocyanin food additive dye or an FDC food additive dye. In some embodiments, the discoloration of food dye additives can be from 0% to 60% after 5 hours under a blue LED emitting at 455 nm with 45 mW/cm2 power. In some embodiments, the degradation is at least 25%, 30%, 40% 50%, and/or 60% of the initial amount of the natural anthocyanin food additive dye after exposure to the heterogeneous material.

[0076] Those of ordinary skill in the art recognize ways to determine whether an heterogeneous material maintains an activity over time; e.g., the durability of the heterogeneous material. In some embodiments, the discoloration of food dye additives decreased from zero% to 60% after 5 hours under a blue LED emitting at 455 nm with 45 mW/cm2 power. For example, in some embodiments, the retention of antibacterial activity is after exposure to 85% relative humidity and 85°C for at least 7 days.

[0077] Exemplary but non-limiting embodiments are as follows:

Embodiment 1. A heterogeneous material comprising:

a p-type semiconductor comprising a first metal oxide compound and a second metal oxide compound, wherein the first metal oxide compound and the second metal oxide compound have different oxidation states of the same metal, and wherein the p-type semiconductor has a p-type valence band; and

an n-type semiconductor having an n-type valence band which is deeper than the p- type valence band, wherein the n-type semiconductor is in ionic charge communication with the p-type semiconductor.

Embodiment 2. The heterogeneous material of embodiment 1 , further comprising a noble metal in ionic charge communication with the first metal oxide compound and the second metal oxide compound.

Embodiment 3. The heterogeneous material of embodiment 2, wherein the noble metal is rhodium, ruthenium, palladium, silver, osmium, platinum or gold.

Embodiment 4. The heterogeneous material of embodiment 2 or 3, wherein the noble metal is loaded onto the n-type semiconductor.

Embodiment s. The heterogeneous material of embodiment 1 , 2, 3, or 4, further comprising a second n-type semiconductor, wherein at least a portion of the second n-type semiconductor is ionic charge isolated from the p-type semiconductor.

Embodiment 6. The heterogeneous material of embodiment 5, wherein the second n- type semiconductor comprises a cerium oxide.

Embodiment 7. The heterogeneous material of embodiment 6, wherein the cerium oxide is Ce0₂. Embodiment 8. The heterogeneous material of embodiment 5, wherein the second n- type semiconductor comprises plural phase Ti0₂.

Embodiment 9. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, or 8, wherein the first metal oxide compound comprises copper(l) and the second metal oxide compound comprises copper(ll), the first metal oxide compound comprises cobalt (II) and the second metal oxide compound comprises cobalt (III), the first metal oxide compound comprises Mn(ll) and the second metal oxide compound comprises Mn(lll), the first metal oxide compound comprises Fe(ll) and the second metal oxide compound comprises Fe(lll), or, the first metal oxide compound comprises and Ir(lll) and the second metal oxide compound comprises Ir(IV).

Embodiment 10. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, or 9, wherein the p-type semiconductor is loaded onto the n-type semiconductor.

Embodiment 11. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, or 9, wherein the p-type semiconductor is substantially uniformly dispersed onto the n-type semiconductor.

Embodiment 12. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or 1 1 , wherein the p-type semiconductor is in the form of particles having a particle size of 100 nm or less.

Embodiment 13. The heterogeneous material of embodiment 9, wherein the p-type semiconductor comprises copper(l) and copper(ll).

Embodiment 14. The heterogeneous material of embodiment 13, wherein the p-type semiconductor comprises Cu_xO.

Embodiment 15. The heterogeneous material of embodiment 14, wherein the Cu_xO is chemically valence controlled.

Embodiment 16. The heterogeneous material of embodiment 9, wherein the ratio of copper(l):copper (II) is between 10:90 to 30:70.

Embodiment 17. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, or 16, wherein the p-type semiconductor is 0.001 to 10 wt% of the heterogeneous material and the n-type semiconductor is 90 to 99.999 wt% of the heterogeneous material.

Embodiment 18. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor is an oxide of cerium, tungsten, tantalum, tin, zinc, strontium, zirconium, barium, indium, or aluminum.

Embodiment 19. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor comprises Sn-Ti(0,C,N)₂, , MgTi₂0₅, Ce0₂, KTa0₃, Ta₂0₅, Sn0₂, W0₃, ZnO, SrTi0₃, BaTi0₃, ZrTi0₄, ln₂Ti0₅, AI₂Ti0₅,

Embodiment 20. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor is AI₂._xln_xTi0₅ wherein 0<x<2.

Embodiment 21. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor is Zr₁._yCe_yTi0₄ wherein 0<y<1 .

Embodiment 22. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor is a titanium oxide having a valence band controlled through doping.

Embodiment 23. The heterogeneous material of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, or 17, wherein the n-type semiconductor is a titanium oxide doped with N, C, or both.

Embodiment 24. The heterogeneous material of embodiment 22, wherein the n-type semiconductor is a titanium oxide comprising a compound represented by the formula

(Tii__rM_r)(0₂-s-tC_sN_t), wherein:

M is Sn, Ni, Sr, Ba, Fe, Bi, V, Mo, W, Zn, Cu, or a combination thereof;

r is from 0 to 0.25;

s is from 0.001 to 0.1 ; and

t is from 0.001 to 0.1 .

Embodiment 25. The heterogeneous material of embodiment 24, comprising

(Tio_.99Sno_.01 )(0₂__s_tC_sN_t), (Tio.9₇Sno.o₃)(0₂__s_tC_sNt), (Tio.9₅Sno.o5)(0₂__s_tC_sNt), (Ti_0.9oSn₀.io)(0₂._s. tC_sN_t), (Tio.85Sno.i₅)(0₂__s_tC_sNt), (Ti₀.985Nio.oi5)(0₂._s.tC_sN_t), (Tio.9₈Nio.o₂)(0₂__s_tC_sNt), (Tio.9₇Ni₀.o₃)(0₂. _s_tCsNt), (Tio_.99Sr₀.oi)(0₂__s_tCsNt), (Tio.9₇Sro.o₃)(0₂__s_tCsNt), (Tio.9₅Sro.o5)(0₂__s_tC_sN_t),

(Tio.9₇Bao.o3)(0₂-s-tCsNt), (Ti₀.95Bao.o5)(0₂-s-tC_sNt), (Tio.94Sno.05Feo.01 )(0₂-_s-tC_sNt),

(Tio.9₄Sno.o5Nio.oi )(0₂._s.tC_sNt), (Ti₀.99Feo.oi)(0₂._s.tC_sN_t), (Tio.9₅Zno.o5)(0₂__s_tC_sNt),

(Tio.₇₇Sno.i₅Cuo.o8)(0₂__s_tC_sNt), (Tio.85Zno.i₅)(0₂__s_tC_sNt), (Ti₀.9oBio.io)(0₂._s.tC_sN_t), (Ti₀.99₆Vo.oo4)(0₂._s. tCsNt), (Tio.984Vo.oi6)(0₂-s-tC_sNt), (Tio.9₇₀Vo.o₃)(0₂-s-tCsNt), (Ti₀.99₇Moo.oo3)(0₂-s-tCsN_t),

(Tio.984MOo.016)(0₂__s_tC_sN_t), (Tio.95₇MOo.043)(0₂__s_tC_sNt), (Tio.9₇Wo.₀₃)(0₂__s_tC_sNt), (Tio.95VV₀.05)(0₂._s. tC_sNt), (Tio.99₆Vo.oo4)(0₂__s_tC_sNt), (Ti₀.984Vo.oi6)(0₂._s.tC_sN_t), or (Ti₀.9₇oVo.o₃)(0₂._s.tC_sN_t).

Embodiment 26. The heterogeneous material of embodiment 16, wherein the n-type semiconductor comprises (Tii._rM_r)(0₂._s._tC_sN_t), wherein:

M is Sn;

r is from 0 to 0.25;

s is from 0.001 to 0.1 ; and t is from 0.001 to 0.1.

Embodiment 27. The heterogeneous material of embodiment 26, wherein r is greater than 0.

Embodiment 28. The heterogeneous material of embodiment 26, wherein r is 0, and the semiconductor comprises a rutile phase and an anatase phase.

Embodiment 29. The heterogeneous material of embodiment 16, wherein the n-type semiconductor is a tin oxide.

Embodiment 30. A method of decomposing a chemical compound, comprising exposing the chemical compound to a photocatalyst comprising the homogeneous material of any of embodiments 1 -29 in the presence of light.

Embodiment 31. The method of embodiment 30, wherein the chemical compound is a pollutant.

Embodiment 32. A method of killing a microbe, comprising exposing the microbe to a photocatalyst comprising the homogeneous material of any of embodiments 1-29 in the presence of light.

EXAMPLES

I. Synthesis

Example 1(a). Synthesis of an n-type semiconductor (Ex-1)

[0078] Ti(CNO)₂:Sn (Ex-1 ): 3.78 g of Tin(ll) 2-ethylhexanoate [also known as tin(ll) octoate and/or stannous octoate] (Spectrum Chemicals, Gardena, CA, USA), 30 ml 50 wt% solution of Titanium(IV) bis(ammonium lactato)dihydroxide (titanium lactate, [Tyzor LA]) (Sigma Aldrich, St. Louis, MO, USA) and 15.0 g of Ammonium nitrate (NH₄N0₃) (Sigma Aldrich, St. Louis, MO, USA) were dissolved in 25 ml of reverse osmosis (RO) purified water, then heated to 150°C and stirred for 20 minutes. The resulting mixture was then heated at 350°C for 40 minutes in a preheated muffle furnace under ambient atmosphere (room atmosphere) and pressure conditions. The resulting powder was placed in the preheated muffle furnace and then annealed at 475°C under ambient conditions for 40 minutes.

Example 1(b). Loading

[0079] Combustion synthesized Ti(0,C,N)₂:Sn (6 g) was mixed with 6M HCI (60 mL) at 90°C for 3 hours in a water bath while stirring. The mixture was then cooled down to room temperature, filtered through 0.2 micron membrane filter paper, washed with 100 to 150 mL of deionized water (Dl) water, and finally dried at room temperature overnight for between 10 to 15 h.

[0080] The weight fraction of Copper to processed Ti(0,C,N)₂:Sn (1g) was 0.01. 10mL aqueous solution of CuCI₂.2H₂0 (26.8 mg) was stirred with 1 g of processed Ti(0,C,N)₂:Sn at 90°C for 1 h. Then, 1.5 ml of aqueous solution containing NaOH (50 mg) and glucose (250 mg) was added to the reaction mixture at 90°C while stirring. After the addition of aqueous solution of glucose and NaOH, the mixture was stirred for another 1 h, then cooled down to room temperature, followed by filtration through 0.2 micron membrane, washing with 100 to 150 mL Dl water and finally dried it at 1 10°C in air oven overnight (10 to 15 h).

[0081] The CuO:Cu₂0 weight ratio in Ex-1 was determined to be 0.789:0.21 1. By comparison, a CuxO/Ti0₂ nanocomposite obtained according to the procedure of Qui, et al., ACS Nano, 6, 1609-1618, had a CuO:Cu₂0 weight ratio of 0.169:0.831.

Example 1(b)'. Comparative Example 0 (CE-0)

[0082] Total weight percent of Cu as 0.25wt.%CuO + 0.125wt.% Cu₂0 was physically mixed with Sn-Ti(OCN)₂ photocatalyst by hand using mortar and pestle in 5-10 mL amount of methanol. The mixing was continued until all the methanol had evaporated.

Example 1(c). Comparative Example 1 (CE-1)

[0083] CE-1 (Ti(CNO)₂:Sn) was prepared in a manner similar to that of Example 1 (a), except that no loading of Cu_xO (step A only) was performed resulting in unloaded Ti(CNO)₂:Sn (no Cu_xO).

Example 1(d). Comparative Example 2 (Ex-1 A)

[0084] Ex-1 A was prepared in a manner similar to that of Example 1 (b) above, except that 25 mg instead of 50 mg of NaOH and 125 mg instead of 250 mg of glucose were used. Example 1(d)'. Comparative Example 2' (Ex-1 B)

[0085] Ex-1 B was prepared in a manner similar to that of Example 1 (b) above, except that the weight fraction of Copper to processed Ti(0,C,N)₂:Sn (1g) was 0.005.

Example 1(e). Comparative Example 3 (Ex-2 and Ex-3)

[0086] Ex-2 (Plasma W0₃) and Ex-3 (commercial GTP W0₃ ) were prepared in a manner similar to that of Ex-1 above, except that the same molar amounts of Plasma W0₃ or commercial GTP-WO3 were used instead of Ti(0,C,N)₂:Sn photocatalyst; NaOH was not added to the reaction mixture and the glucose amount was 125 mg instead of 250 mg. Plasma W0₃ was made in a similar manner to that described in U.S. Patent Application No 13/738,243, filed January 10, 2013 which is incorporated by reference herein for its teachings regarding the same. GTP W0₃ was purchased from Global Tungsten & Powder (Towanda, PA, USA) and used without additional purification or annealing.

[0087] 0.159 mL of 1 molar solution Bis(Ethylenediamine) copper (II) hydroxide was mixed with 10 mL of RO water and it was stirred with 1g of W0₃ at 90°C for 1 h. Then, glucose (125 mg) was added to the reaction mixture at 90°C while stirring. After the addition of the aqueous solution of glucose the mixture was stirred for another 1 h, then cooled down to room temperature, followed by filtration through 0.2 micron membrane, washing with 100 to 150 ml. Dl water and finally dried it at 1 10°C in air oven overnight (10 to 15 h).

Example 1(f). Comparative Example 4 (Ex-4, Ex-5, Ex-6, CE-2)

[0088] Ex-4, Ex-5, Ex-6 and CE-2 were prepared in a manner similar to that of Ex-1 , except that the same molar amounts of Ce0₂ were used instead of Ti(0,C,N)₂:Sn. In addition, the loading conditions were modified as follows: Ex-4: aqueous solution of NaOH (25 mg) and glucose (125 mg); Ex-5: without glucose; Ex-6: the concentration of glucose (62.5 mg) and NaOH (25 mg).

[0089] CE-2 is analogous to CE-1 , except that CE-2 is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn ) of Ce0₂ (Sigma Aldrich, St. Louis, MO, USA). Ce0₂ was used as received from the vendor without additional purification or annealing.

Example 1(g). Comparative Example 5 (Ex-7, CE-3)

[0090] Ex-7 was prepared in a manner similar to that of Ex-1 above, except that the same molar amount of insulator, Al₂0₃ was used instead of Ti(0,C,N)₂:Sn, 25 mg of NaOH was used, and 125 mg of glucose was used. The Cu_xO loading was 1 wt% Cu with respect to Al₂0₃. CE-3 is analogous to CE-1 , except that CE-3 is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn ) of Al₂0₃. Al₂0₃ was used as received from the vendor without additional purification or annealing.

Example 1(h). Comparative Example 6 (Ex-8, CE-4)

[0091] Ex-8 was prepared in a manner similar to that of Ex-1 above, except that the same molar amount of n-type UV active photocatalyst, Ta₂0₅ was used instead of Ti(0,C,N)₂:Sn, 25 mg of NaOH and 125 mg of glucose were used. The Cu_xO loading was 1 wt% Cu with respect to Ta₂0₅. CE-4 is analogous to CE-1 , except that CE-4 is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn ) of Ta₂0₅ (Sigma Aldrich, St. Louis, MO, USA). Ta₂0₅ was used as received from the vendor without additional purification or annealing.

Example 1(i). Comparative Example 7 (Ex-9, Ex-10, Ex-11, Ex-19, Ex-20, CE-4A)

[0092] Ex-9 was prepared in a manner similar to that of Ex-1 above, except that the same amount of n-type UV active photocatalyst, Sn0₂ was used instead of Ti(0,C,N)₂:Sn. The CuxO loading was 1 wt% Cu with respect to Sn0₂. The nanosize Sn0₂ (US Research Nanomaterial, Houston, TX, USA) had been annealed at 900°C in a box furnace in air for 1 h. It was then soaked in 6M HCI aqueous solution as in Ex-1. In Ex-10, the amount of NaOH was 25 mg and the amount of glucose used was 125 mg. In Ex-1 1 , the amount of NaOH was 75 mg and the amount of glucose was 375 mg. In Ex-19 and Ex-20 the annealed Sn0₂ was not soaked in 6M HCI aqueous solution as in Ex-1 , Ex-10, Ex-1 1. In Ex-19, the amount of NaOH was 25 mg and the amount of glucose used was 3 mg. In Ex-20, the amount of NaOH was 25 mg and the amount of glucose was 10 mg. CE-4A is analogous to CE-1 , except that CE-4A is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn) of Sn02. With varying amounts of NaOH and glucose while loading fixed amount of 1 wt% Cu with respect of Sn0_2, different appearances of body color resulted.

Example 1(j). Comparative Example 8 (Ex-12, CE-5, Ex-13)

[0093] Ex-12 was prepared in a manner similar to that of Ex-1 B above. Loading of Cu_xO was performed on rutile Ti0₂ (Tayca, Inc. Osaka, JP) except that 25 mg instead of 50 mg of NaOH and 125 mg instead of 250 mg of glucose were used.

[0094] CE-5 is analogous to CE-1 , except that CE-5 is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn) of Rutile Ti02 (Tayca, Inc. Osaka, JP). Rutile Ti02 was used as received from the vendor without additional purification or annealing.

[0095] For Ex-13, 10 g Commercial W0₃ (Global Tungsten Powder, Sylvania, PA, USA) was annealed at 400°C for 1 hour. [Pt(NH₃)₄]CI₂ (0.181 mg Alfa Aesar, Ward Hill, MA, USA)] was dissolved in 15.0 mL RO water and stirred with 2.0 g of the annealed W0₃ at room temperature (RT) for 2h. Then, it was filtered through membrane filter paper of pore size 0.2 micron and washed with RO water and dried at 120°C overnight. The resulting material was annealed at 400 °C for another 1 h in air.

Example 1(k). Comparative Example 9 (Ex-13-17, CE-6)

[0096] Ex-14 to Ex-17 were prepared in a manner similar those described above except that different amounts of [Pt(NH₃)₄]CI₂] and/or lrCI₃/lr0₂ were dissolved in the 15 mL of RO water. See Table 1 as follows:

Table 1

[0097] CE-6 is analogous to CE-1 , except that CE-5 is an equivalent unloaded molar amount (to Ti(0,C,N)₂:Sn ) of W0₃ (Global Tungsten Powder, PA, USA). W0₃ was used as received from the vendor without additional purification or annealing.

Example 1(1). Synthesis of an n-type semiconductor (Ex-18)

[0098] MgTi205 synthesis: 2.663 g Mg(N0₃)₂-6H₂0 (Sigma Aldrich, St. Louis, MO, USA), 5 g ammonium nitrate (Sigma Aldrich, St. Louis, MO, USA), 1.5g Urea (Sigma Aldrich, St. Louis, MO, USA) and 10mL of Titanium(IV) bis(ammonium lactate)hydroxide (titanium lactate, [Tyzor LA]) (Sigma Aldrich, St. Louis, MO, USA) were dissolved in about 10 mL of Dl water in 250 mL of low-form Pyrex beaker. The resulting mixture was then heated at 350°C for 20 minutes in a preheated muffle furnace under ambient atmosphere (room atmosphere) and pressure conditions. The resulting powder was placed in the preheated muffle furnace and then annealed at 600°C under ambient conditions for about 30 minutes.

Cu_xO loaded MgTi₂0₅: Cu_xO was loaded onto the MgTi₂0₅ in a manner similar to that described in Example 1 (b), except that in this preparation, no HCI preparation step was used. The NaOH preparation step used was similar to that described in Example 1 (b). The weight fraction of copper to MgTi₂0₅ was 0.01. 10mL aqueous solution of CuCI₂*2H20 (26.8 mg) was stirred with 1g of MgTi₂0₅ at about 90°C for about 1 h. Then, 1.5mL of aqueous solution containing NaOH(25 mg) and glucose (125 mg) was added to the reaction mixture at about 90°C while stirring. After the addition of aqueous solution of glucose and NaOH, the mixture was stirred for about another 1 h, then cooled down to room temperature, followed by filtration through 0.05 micron membrane, washing with 100 to 150mL Dl water and finally dried it at 1 10°C in air oven for about 2h.

Example 1(m). (Ex-20 (Cu_xO loaded plural phase Ti0₂))

The plural phasic n-type semiconductor was loaded onto CuxO in a manner similar to that in Example 1 (b). The weight fraction of copper to plural phasic n-type semiconductor (87% anatase phase Ti02/13% rutile phase Ti0₂ sold under the brand name "P25" [EvoniK Degussa, NJ, USA]) was 0.01. 15mL aqueous solution of CuCI₂-2H₂0 (26.8 mg) was stirred with 1g of P25 at about 90°C for 1 h. Then, 1.5mL of aqueous solution containing NaOH(25mg) and glucose (125mg) was added to the reaction mixture at about 90°C while stirring. After the addition of aqueous solution of glucose and NaOH, the mixture was stirred for about another 1 h, then cooled down to room temperature, followed by filtration through 0.05 micron membrane, washing with 100 to 150mL Dl water and finally dried it at 1 10°C in air oven for about 2h.

Example 1(n) (CE-7)

[0099] Comparative Example CE-7 was prepared in a manner similar to Example 1 (m) except that 0.25wt.%CuO+0.125wt.%Cu2O was physically mixed with 0.625wt% P25 in methanol (5-1 OmL) by hand until the methanol is substantially all evaporated.

Example 1(o). (Ex-19 (AgVW0₆))

[00100] 4.12 g of Vanadyl oxalate (Stratcor, Inc, Arkansas, USA), 0.3 g glycine (Sigma Aldrich, St. Louis, MO, USA), 0.62 g Ammonium Nitrate (Sigma Aldrich, St. Louis, MO, USA) and 1.484 g Ammonium meta tungstate (Global Tungsten & Powder, PA, USA) were dissolved in about 5 mL of reverse osmosis (RO) purified water. To this solution 1g silver nitrate (Alfa Aesar, USA) was added to get brownish slurry in 250 mL low form beaker, then, the resulting mixture was then heated at about 350°C for about 20 min in a preheated muffle furnace under ambient atmosphere (room atmosphere) and pressure conditions. The resulting powder was placed in the preheated muffle furnace and then, annealed at about 500°C under ambient conditions for about 60 minutes, which has resulted in yellow powder (Ex-19).

Example 1(p). (Ex-20 (AgCa2Zn₂V₃0i2))

[00101] 6.19 g of vanadyl oxalate (Stratcor, Inc, Arkansas, USA), 1.1 1 g glycine (Sigma Aldrich, St. Louis, MO, USA), 1.75 g zinc nitrate hexahydrate (Sigma Aldrich, St. Louis, MO, USA), 1.39 g Calcium nitrate tetrahydrate (Sigma Aldrich, St. Louis, MO, USA), 2.49 g ammonium nitrate (Sigma Aldrich, St. Louis, MO, USA) were dissolved in about 10 mL of reverse osmosis (RO) purified water. To this solution 0.5105 g silver nitrate (Alfa Aesar, USA) was added to get brownish slurry in 250 mL low form glass beaker, then, the resulting mixture was then heated at about 350°C for about 20 min in a preheated muffle furnace under ambient atmosphere (room atmosphere) and pressure conditions. The resulting powder was placed in the preheated muffle furnace and then, annealed at about 600°C under ambient conditions for about 60 minutes, which resulted in yellow powder (Ex-20). Example 1(q). (Ex-21 (Ag₃P0₄))

[00102] 5 g of silver nitrate (Alfa Aesar, USA) was dissolved in 10 mL of reverse osmosis (RO) purified water in 50 mL glass beaker. In a separate 50 mL glass beaker, 1.128 g of ammonium dihydrogen phosphate (Sigma Aldrich, St. Louis, MO, USA) was dissolved in 10 mL of reverse osmosis (RO) purified water. To the aqueous solution of ammonium dihydrogen phosphate aqueous solution of silver nitrate was added drop by drop while stirring the ammonium dihydrogen phosphate solution. The yellow precipitate formed during this addition at room temperature was finally filtered and dried at 1 10°C for 2h in air oven.

Example 2: Characterization of supported P-cats

Example 2(a): Powder XRD characterization (Ex-1A, CE-1, Ex-4, CE-2, Ex-7 and CE-3)

[00103] Powder samples of Ex-1A, CE-1 , Ex-4, CE-2, Ex-7 and CE-3 were analyzed using powder x-ray diffraction using Cu K-alpha radiation (Rigaku Miniflex II [Rigaku Americas, Woodland, TX, USA) with 1 °/min. The result of the X-ray diffraction analysis of Ex-1 and CE- 1 is shown in FIG. 3 and confirms the presence of anatase Ti0₂. It was confirmed from XRD patterns (Fig.3) that the anatase phase of Ti(0,C,N)2:Sn is retained even after Cu_xO loading because comparison of the resulting XRD spectrogram with Joint committed powder diffraction standards, card no. 00-021-1272 [anatase-Ti02] (JCPDS) by International Centre for Diffraction Data (Newton Square, PA, USA) exhibits substantially the same peaks as the anatase phase spectrogram (the phase of the material generally visible light photocatalytically active).

[00104] In addition, powder samples of Ex-4 and Ex-7 were analyzed in a manner similar to that of Ex-1A above, except that equal molar amounts of Ex-4 and Ex7 were used instead of Ex-1A. The results are shown in FIGS. 4 and 5, respectively-using powder x-ray diffraction using Cu K-alpha radiation (Rigaku Miniflex II [Rigaku Americas, Woodland, TX, USA) with I min. The result of the X-ray diffraction shown in FIGS. 4 and 5 confirms the Cu_xO loading did not substantially affect the bulk semiconducting phase of the respective n-type material Example 2(b): DRS Characterization

[00105] Powder samples of Ex-1A, CE-1 (FIG. 6); Ex-4 and CE-2 (FIG. 7), Ex-7 and CE-3 (FIG. 8) were analyzed using diffuse reflectance spectroscopy (DRS). The results are shown in FIGURES 6, 7 and 8, and indicate that at least tin doping (Ex-1A), Ce0₂ (Ex-4) and AI₂0₃(Ex-7) appeared to improve absorption in the visible spectrum (400nm to 800nm), whereas CE-1 , CE-2 and CE-3 did not. Therefore, the anatase Ti02 observed in the XRD pattern and visible absorption due to the anatase phase confirmed the loading of Ti(0,C,N)₂:Sn, Ce0₂, and Al₂0₃ on the substrate. The loaded Cu_xO had absorption in the longer wavelength side of absorption edge of semiconductors and if the loaded Cu_xO had a mixture of CuO and Cu₂0, then their characteristics absorptions between 600 and 800 nm and 500 and 600 nm respectively would have been observed, in addition to absorption of loaded Cu_xO.

Example 3. Experimental set-up for photocatalysis (Ex-1A and CE-1)

[00106] Ex-1A (130 mg), as prepared according to the methods described earlier in this disclosure, was added to 1.04 ml Dl water in order to make a coating solution which was 10 wt% solid materials in water. The resulting dispersion was homogenized using an ultrasonic homogenizer. A glass substrate (50 mm x 75 mm) was coated with the prepared resultant by using a spin coater (1200 rpm/ 40 sec). The coated substrate was heated for 2 minutes at 120°C. Another slide was prepared in the same manner except that CE-1 (130 mg) was used instead of Ex-1A.

[00107] The spin coated glass slides were heated at 120°C on a hot plate under full spectrum irradiation by a Xe (xenon) lamp (lamp power output 300 W) for 1 hour. Each slide was then sealed in a separate 5 L Tedlar bag under vacuum, followed by injecting 3L of ambient air and 80 ml_ of 3500 ppm acetaldehyde. Each bag was lightly massaged for 2 minutes by hand then placed in the dark for 15 min. The acetaldehyde concentration was estimated by Gas Chromatography-Flame Ionization Detector (GC-FID) to be at 80±2 ppm. Each Tedlar bag containing a sample was placed back in the dark for 1 hour. The slide/Tedlar bag was exposed to array blue LED of 455 nm with light intensity of 270 mW/cm². A sample was collected every 30 minutes by an automated injection port of GC- FID and the amount of remaining acetaldehyde was estimated at subsequent 30 minute intervals. FIG. 9 is a graph illustrating Ex-1A VOC performance data. The graph shows that generally when Ti(CNO)₂:Sn is combined with Cu_xO (Ex-1A), performance is improved when compared to bare Ti(CNO)₂:Sn (CE-1 ).

Example 4. Antibacterial experiments.

Example 4A.

[00108] Substrate (1 " x 2" glass slide) was prepared by sequential application of 70% IPA (Isopropyl Alcohol) and 100% ethanol (EtOH) and then dried in air. Ex-1 B was dispersed in 100% EtOH at 2mg/ml_ concentration and then 100 uL of the suspension was applied to the substrate, and then dried. The application process was repeated 5 times to attain 1 mg of Ex-1 B on the substrate. The substrate was then dried at room temperature. The coated substrates were placed in a glass dish with a water soaked filter paper for maintaining moisture, and glass spacers were inserted between the substrate and the filter paper to separate them.

[00109] E. coli (ATCC 8739) was streaked onto a 10 cm diameter petri dish containing 20 ml of LB (lysogeny broth/ luria broth) agar, and incubated at 37°C overnight. For each experiment, a single colony was picked to inoculate 3ml_ nutrient broth, and the inoculated culture was incubated at 37°C for 16 hours to create an overnight culture (-109 cells/mL). A fresh log-phase culture of the overnight culture was obtained by diluting the overnight culture x100, inoculating another 5 cm petri dish with LB agar and incubating at 37°C for 2.5 hr. The fresh culture was diluted 50x with 0.85% saline, which gave a cell suspension of 2 x 10⁶ cells/mL. 50 μί of the cell suspension was pipetted onto each deposited glass substrate. A sterilized (in 70% and then 100% EtOH) plastic film (20 mm x 40 mm) was placed over the suspension to spread evenly under the film. The specimen was kept in the dark (Cu_x0₂- Dark) or then irradiated under blue LED light (455 nm, 10 mW/cm2) (Cu0₂-light). At chosen time points, e.g., 30 min/60 min increments, the specimen was placed in 10mL of 0.85% saline and vortexed to wash off the bacteria. The wash off suspension was retained, then serially diluted using 0.85% saline, and then plated on LB agar and incubated at 37°C overnight to determine the number of viable cells in terms of CFU/Specimen.

[00110] The results are shown in FIGS. 10 and 1 1. It appears that E-coli killing property due to presence of flexible copper ion was observed even in the dark within 30 min (See FIGS. 10 and 1 1 ).

[00111] FIG 10 also shows the property of Cu¹⁺ after loading on Ce0₂ that complete killing of E-coli is observed in 1 h for dark as well as under 10 mW/cm2 blue LED of 455 nm light. Therefore, Cu_xO loaded Ce0₂ is a good functional material for E-Coli killing. Example 4B

[00112] Ex-1 powder was prepared as described in Example 1. The powder was then kept in the dark at 85% relative humidity and 85°C for a period of 7 days. The slide[s] were then prepared and tested for antibacterial activity in the same manner as described in Example 4A. The results are shown in FIG.12A. The results show that even after exposure to 85% relative humidity and 85°C for a period of 7 days, Ex-1 demonstrated retained photocatalytic activity.

Example 4C

[00113] Ex-7 powder was prepared as described above. The powder was then kept in the dark at 300°C for 20 minutes. The slide[s] were then prepared and tested for antibacterial activity in the same manner as described in Example 4A. The results are shown in FIG.12B. The results show that even after exposure to 300°C for 20 minutes, Ex-7 retained photocatalytic activity.

Example 5. Photocatalysis experiments for dye discoloration studies

Example 5A.

[00114] The photocatalytic properties for Ex-1 , CE-1 and rutile Ti02 loaded with and without Cu_xO were compared by measuring the degradation of food additive dye (Natural Blue Colored powder, Color Maker, Anaheim, California, USA) as natural blue color powder 2.85 g of the natural blue color powder was dissolved in 100 ml_ of RO water creating a blue powder stock solution. 150 mg of each sample was placed in RO water (27 ml_) with natural blue color 3ml_ of blue powder stack solution for 1 hour without any light and then exposed to a blue light emitting diode (455 nm, 45 mW/cm²) for 5 hours. The degradation of the resulting blue colored solution was measured at 1 h, 3h and 5h by monitoring its concentration using UV-Vis absorption spectroscopy (Cary-50, Spectrophotometer Agilent Technologies, Santa Clara, CA, USA). The concentration was calculated as intensity of the peak at 600 nm. The results are shown in FIGURE 13. Table 2 below compares the final degradation results of the four photocatalytic materials.

Table 2: Comparison of final dye discoloration results by four different photocatalysts.

5B

The photocatalytic properties for Ex-18 (Cu_xO loaded MgTi205 were examined by measuring the degradation of food additive dye (Natural Blue Colored powder, Color Maker, Anaheim, California, USA) as natural blue color powder. The degradation was examined in the manner described in Example 5A. The results are shown in Fig. 17.

Photocatalysis experiments for anti-bacterial studies Example 6A.

[00115] 130 mg of each powdered sample (Examples 14-18 described above) was dissolved in a minimal amount of RO water (ca-15 mL) and homogenized for 5 minutes.

[00116] A clean petri dish was wiped with ethanol and the inside surface of the dish was ionized with a plasma device for 1 to 2 minutes. The homogeneous sample of each compound was poured into the treated petri dish and then heated at 120°C while swirling to increase uniform distribution of the sample as it dried. After the sample had dried, the Petri Dish was placed under a UV Lamp (300W) for 1 hour. Each petri dish was then sealed in a separate 5 L Tedlar bag under vacuum, followed by injecting 3L of ambient air and 80 mL of 3500 ppm acetaldehyde. Each bag was lightly massaged for 2 minutes by hand then placed in the dark for 15 min. The acetaldehyde concentration was estimated by Gas Chromotagraphy-Flame Ionization Detector (GC-FID) to be at 80±2 ppm. Each Tedlar bag containing a sample was placed back in the dark for 1 hour. The slide/Tedlar bag was exposed to array blue LED of 455 nm with light intensity of 0.656 mW/cm². A sample was collected every 30 minutes by an automated injection port of GC-FID and the amount of remaining acetaldehyde was estimated at subsequent 30 minute intervals. The results are shown in Table 3 below.

Table 3

[00117] FIG.14 shows the decomposition rate of acetylaldehyde (Ct/Co) with W0₃ (commercial GTP) (CE-6), 0.05 mol% Pt loaded W0₃ (Ex-13), 0.1 mol% Ir0₂ loaded W0₃ (Ex-16) and both 0.05 mol% Pt and 0.1 mol% Ir02 loaded W0₃ (two times) (Ex-17). It is quite interesting to observe the results that Pt loading has a positive effect and Ir0₂ alone loaded W0₃ has no effect on acetaldehyde decomposition under blue LED of 455 nm (0.656 mW/cm²). However, when both Pt (0.05 mol%) and Ir0₂ (0.1 mol%) loaded on W0₃ has resulted in further enhancement in the photodegradation of acetaldehyde under the same conditions when compared to that of Pt (0.05 mol%) alone or Ir0₂ (0.1 mol%) alone or bare GTP W0₃ alone.

Example 5c

[00118] The photocatalytic properties for Ex-10 (Sn0₂), CE-4A and food additive dye FD&C Blue No.2 dye alone were compared by measuring the degradation of food additive dye FD&C Blue No.2 dye (Synthetic blue colored powder, Chromatech, Inc, Michigan, USA), g of the natural blue color powder was dissolved in 100 mL of RO water creating a blue powder stock solution. 150 mg of each sample was placed. The photocatalytic properties were determined in a manner described in Example 5a. The results are shown in FIG. 15.

[00119] The photocatalytic properties for Ex-18 (MgTi0₅), and Ex-1 (SnTi (OCN)₂ ) loaded with Cu_xO were compared by measuring the degradation of food additive dye FD&C Blue No.2 dye (Synthetic blue colored powder, Chromatech, Inc, Michigan, USA). 2.85 g of the natural blue color powder was dissolved in 100 mL of RO water creating a blue powder stock solution. 150 mg of each sample was placed. The photocatalytic properties were determined in a manner described in Example 5a. The results are shown in FIG.16.

Example 6 Photocatalytic Inactivation of E. coli (ATCC 8739)

6A Method:

[00120] Substrate (1 " x 2" glass slide) was prepared by sequential application of 70% IPA (Isopropyl Alcohol), 100% EtOH and then dried in air. Ex-1 B was dispersed in 100% EtOH at 2mg/mL concentration and then about 100 uL of the suspension was applied to the substrate, and then dried. The application process was repeated 5 times to attain about 1 mg of Ex-1 B on the substrate. The substrate was then dried at room temperature. The coated substrates were placed in a glass dish with a water soaked filter paper for maintaining moisture. Glass spacers were inserted between the substrates and the filter paper to separate the substrates from the filter paper.

[00121] E. coli (ATCC 8739) was streaked onto a 5 cm diameter petri dish containing about 25 ml of LB agar, and incubated at about 37°C overnight. For each experiment, a single colony was picked to inoculate about 3 mL nutrient broth, and the inoculated culture was incubated at about 37°C for about 16 hours to create an overnight culture (~10⁹ cells/mL). A fresh log-phase culture of the overnight culture was obtained by diluting the overnight culture x100, inoculating another 5 cm petri dish with LB agar and then incubated at about 37°C for about 2.5 hr. The fresh culture was diluted 50x, which gave a cell suspension of about 2 x 10⁶ cells/mL. 50uL of the cell suspension was pipetted onto each glass substrate. A sterilized (in 70% and then 100% EtOH) plastic film (20 mm x 40 mm) was placed over the suspension to spread the suspension evenly under the film. At chosen time point, e.g., about 30 minute increments, the specimen was placed in 10ml_ of 0.85% saline and vortexed at 3200 rpm for about 1 min to wash off the bacteria. The wash off suspension was serially diluted using 0.85% saline, and plated on LB agar and incubated at about 37°C overnight to determine the number of viable cells in terms of CFU/Specimen. Counting was performed by visual inspection and the result multiplied by the dilution factor to arrive at the determined number. The specimen was then irradiated and positioned under a 455 nm blue light emitting LED to provide about 45 mw/cm² to the specimen. The results are shown in FIG. 19.

[00122] The anti-bacterial properties of CE-7 and Ex-7A were determined as described in Example 6A, except that molar equivalent amount of CE-7 and Ex-7A were used instead of Ex-1 B. The results are shown in FIGs 17 (CE-7) and 18 (Ex-7A).

[00123] The anti-bacterial properties of Ex-1 (loaded 1 % Cu_xO/Sn:Ti(OCN)₂), Cu_xO only and unloaded Sn:Ti(OCN)₂ (as described in Example 1 (a)) were compared by measuring the antibacterial activity as described in Example 6A. The results are shown in FIG. 20.

Function of Peat I

[00124] 50 mg of Cu_xO/P25 (as produced in Example 1 (m)) was mixed with 1 mL of 10% bleach (Clorox Germincidal, NaCIO based) in a 1.6 mL Eppendorf centrifuge tube, and incubated at room temperature (-24 C) for two hours, with shaking (setting 9 on an analog VWR vortex). After incubation, the tube was centrifuged in an Eppendorf 5430 microcentrifuge (2 minutes at 14167 rcf), after which the particles formed a solid pellet at the bottom of the tube. The clear supernatant was carefully removed, and 1 mL of Dl water was added. The tube was vortexed until the pellet was fully disrupted and the suspension became homogeneous. It was then centrifuged again. This process was repeated four more times.

[00125] After the final centrifugation, the pellet was resuspended in 1 mL of Dl water, and mixed with 4 mL of Dl water in a 20 mL clear glass vial with lid. 5 mL of methanol was added, bringing the total volume in the vial to -10 mL.

[00126] A magnetic stir bar (1/2" x 1/8", disposable) was added to the vial, and placed on a stir plate (1000 rpm). A300 W Xenon lamp (Oriel 6881 1 ) was placed about 15 cm away from the vial wall. The irradiation lasted 1 hour in a vented hood, and there was negligible temperature change in the vial during the process.

[00127] After irradiation, the content of the vial was centrifuged to remove all the liquid. The pellet was dried in vacuum, and resuspended in 25 mL of 200 proof ethyl alcohol. The mixture was then sonicated in a sonicator for twenty minutes. [00128] One hundred microliters of the sonicated dispersion was spread evenly on one side of a 1 " by 2" glass slide. After the surface was dry (in a vented hood), the process was repeated, for a total of five coatings. The coated slide was then used in our standard bacterial test.

[00129] For the purpose of control, 50 mg of Cu_xO/AI₂0₃ was treated in the same manner as above, and was then used to make coated slides. These control slides were subjected to standard bacterial test in the same manner as Cu_xO/P25. The results from the dark tests were plotted.

[00130] As shown in the FIG. 22 (left plot), fresh Cu_xO/P25 (1 ) showed high activity, reducing E. coli by 3 log units in 30 minutes in darkness. The bleach treated material (2) showed much reduction in activity, only achieving 3 log reduction after 2 hours in darkness. Once bleach treated, the material was irradiated with a Xenon lamp, however, the resulted sample (3) showed activity comparable to an untreated sample (1 ), also achieving 3 log reduction in thirty minutes.

[00131] In contrast, such regain of function by irradiation was not seen in the case of Cu_xO/AI₂0₃ (FIG. 22, right plot), as the bleach treated/ irradiated sample (3) showed activity similar to that of the bleach treated only sample (2), but significantly lower than that of the fresh sample (1 ).

Function of Peat II

[00132] To investigate how the duration of bleach treatment affected the activity of the copper oxide loaded material, the above experiments were carried out with the bleach treatment duration set for 2 and 16 hours. All other aspects of the experiment remained the same. The log reduction results from these treated samples were plotted together with that from untreated material.

[00133] In FIG. 23, left plot, bleach treatment of Cu_xO/AI₂0₃ led to significant drop of dark activity. Test under light was not able to restore activity to any great extent. In contrast, in the case of Cu_xO/Pcat (P25) (FIG. 23, right plot), while dark activity was similarly affected, light activity was restored. The key point for this experiment was that even after 16 hours of bleach treatment, the light restoration process was still largely intact, a strong testimony to the durability of Cu_xO/P25.

Aqueous combustion synthesis of Boron doped WQ3:

[00134] Aqueous combustion method was used to prepare Boron Doped W03 with Epsilon Phase.

[00135] 5 gm Ammonium Meta Tungstate hydrate (Inframat Advanced Materials, Manchester, CT, USA), 100 mg Boric Acid (Sigma-Aldrich, St. Louis MO, USA), 2 g Carbohydrazide (Sigma-Aldrich) and 10 g ammonium nitrate (Sigma-Aldrich) were dissolved in 50 ml of Dl water. The aqueous solution was then place in a muffle furnace, preheated to about 420°C until combustion was substantially completed (for about 20 minutes). After the combustion was over, the product was annealed in air at about 425 °C for about 30 min. The body color of the powder appeared orange-yellow in color and it was confirmed by comparision with powder XRD pattern (Fig.1 ) with a standard epsilon W0₃ x-ray diffraction (ICFF PDF card number 01-087-2404)

[00136] Fig.1 : Powder XRD pattern (right).

Surface Modification of Eosilon WQ3 by Strong and Selective Adsorption Method using Cobalt oxide:

[00137] 1 gm of Epsilon W0₃ and 40.37 g of CoCI₂*4H₂0 were dissolved in about 10ml_ Dl water and stirred at about 90 °C for about 2 hr in a 40ml_ closed vial reactor. Then, the closed vial reactor was quenched in tap water and filtered through a membrane filter [fine to 0.05 micron], washed with Dl water several times (at least about 250 ml) and finally dried at about 1 10 °C for about 2hr to get cobalt oxide loaded Epsilon W0₃.

[00138] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[00139] The terms "a," "an," "the" and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of any claim. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[00140] Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[00141] Certain embodiments are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, the claims include all modifications and equivalents of the subject matter recited in the claims as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context.

[00142] In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the claims. Other modifications that may be employed are within the scope of the claims. Thus, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Accordingly, the claims are not limited to embodiments precisely as shown and described.

Claims

WHAT IS CLAIMED IS:

1. A heterogeneous material comprising:

a p-type semiconductor comprising a first metal oxide compound and a second metal oxide compound, wherein the first metal oxide compound and the second metal oxide compound have different oxidation states of the same metal, and wherein the p-type semiconductor has a p-type valence band; and

an n-type semiconductor having an n-type valence band which is deeper than the p- type valence band, wherein the n-type semiconductor is in ionic charge communication with the p-type semiconductor.

2. The heterogeneous material of claim 1 , further comprising a noble metal in ionic charge communication with the first metal oxide compound and the second metal oxide compound.

3. The heterogeneous material of claim 2, wherein the noble metal is rhodium, ruthenium, palladium, silver, osmium, platinum or gold.

4. The heterogeneous material of claim 2, wherein the noble metal is loaded onto the n- type semiconductor.

5. The heterogeneous material of claim 1 , further comprising a second n-type semiconductor, wherein at least a portion of the second n-type semiconductor is ionic charge isolated from the p-type semiconductor.

6. The heterogeneous material of claim 5, wherein the second n-type semiconductor comprises a cerium oxide.

7. The heterogeneous material of claim 6, wherein the cerium oxide is Ce0₂.

8. The heterogeneous material of claim 5, wherein the second n-type semiconductor comprises plural phase Ti0₂.

9. The heterogeneous material of claim 1 , wherein the first metal oxide compound comprises copper(l) and the second metal oxide compound comprises copper(ll), the first metal oxide compound comprises cobalt (II) and the second metal oxide compound comprises cobalt (III), the first metal oxide compound comprises Mn(ll) and the second metal oxide compound comprises Mn(lll), the first metal oxide compound comprises Fe(ll) and the second metal oxide compound comprises Fe(lll), or, the first metal oxide compound comprises and Ir(lll) and the second metal oxide compound comprises Ir(IV).

10. The heterogeneous material of claim 1 , wherein the p-type semiconductor is loaded onto the n-type semiconductor.

11. The heterogeneous material of claim 1 , wherein the p-type semiconductor is substantially uniformly dispersed onto the n-type semiconductor.

12. The heterogeneous material of claim 1 , wherein the p-type semiconductor is in the form of particles having a particle size of 100 nm or less.

13. The heterogeneous material of claim 9, wherein the p-type semiconductor comprises copper(l) and copper(ll).

14. The heterogeneous material of claim 13, wherein the p-type semiconductor comprises Cu_xO.

15. The heterogeneous material of claim 14, wherein the Cu_xO is chemically valence controlled.

16. The heterogeneous material of claim 9, wherein the ratio of copper(l):copper (II) is between 10:90 to 30:70.

17. The heterogeneous material of claim 1 , wherein the p-type semiconductor is 0.001 to 10 wt% of the heterogeneous material and the n-type semiconductor is 90 to 99.999 wt% of the heterogeneous material.

18. The heterogeneous material of claim 1 , wherein the n-type semiconductor is an oxide of cerium, tungsten, tantalum, tin, zinc, strontium, zirconium, barium, indium, or aluminum.

19. The heterogeneous material of claim 1 , wherein the n-type semiconductor comprises Sn-Ti(0,C,N)₂, , MgTi₂0₅, Ce0₂, KTa0₃, Ta₂0₅, Sn0₂, W0₃, ZnO, SrTi0₃, BaTi0₃, ZrTi0₄, ln₂Ti0₅, AI₂Ti0₅, or LiCa₂Zn₂V₃0i₂.

20. The heterogeneous material of claim 1 , wherein the n-type semiconductor is Al₂. _xln_xTi0₅ wherein 0<x<2.

21. The heterogeneous material of claim 1 , wherein the n-type semiconductor is Zri_ _yCe_yTi0₄ wherein 0<y<1.

22. The heterogeneous material of claim 1 , wherein the n-type semiconductor is a titanium oxide having a valence band controlled through doping.

23. The heterogeneous material of claim 1 , wherein the n-type semiconductor is a titanium oxide doped with N, C, or both.

24. The heterogeneous material of claim 1 wherein the n-type semiconductor is a titanium oxide comprising a compound represented by the formula

wherein:

M is Sn, Ni, Sr, Ba, Fe, Bi, V, Mo, W, Zn, Cu, or a combination thereof;

r is from 0 to 0.25;

s is from 0.001 to 0.1 ; and

t is from 0.001 to 0.1.

25. The heterogeneous material of claim 24, comprising (Ti₀.99Sno.oi)(0₂-_s-tC_sN_t),

(Tio.9₇Sno.o₃)(0₂__s_tC_sNt), (Tio.9₅Sno.o5)(0₂__s_tC_sNt), (Ti₀.9oSno.io)(0₂._s.tC_sN_t), (Ti₀.85Sno.i₅)(0₂._s. tC_sN_t), (Tio.985Nio.oi5)(0₂__s_tC_sN_t), (Tio.9₈Nio.o₂)(0₂__s_tC_sN_t), (Tio.9₇Nio.o₃)(0₂__s_tCsNt), (Tio.99Sro.01 )(0₂-s-tCsNt), (Ti₀.97Sro.o3)(0₂-s-tCsNt), (Tio.95Sro.o5)(0₂-s-tC_sN_t), (Tio.9₇Bao.o3)(0₂__s_ tC_sN_t), (Tio.9₅Bao.o5)(0₂._s.tC_sNt), (Tio.94Srio.05Feo.01 )(0₂._s._tC_sN_t), (Tio.94Srio.05Nio.01 )(0₂._s._tC_sN_t), (Tio.99Feo.oi)(0₂._s._tC_sNt), (Tio.9₅Zno.o5)(0₂__s_tC_sNt), (Tio.77Sno.i₅Cuo.o8)(0₂._s.tC_sNt), (Ti₀.85Zno.i₅)(0₂._s. tC_sN_t), (Tio.9oBio.io)(0₂-s-tC_sNt), (Tio.99₆Vo.oo4)(0₂__s_tCsNt), (Ti₀.984Vo.oi6)(0₂._s.tC_sN_t),

(Tio.97oVo.03)(0₂-s-tC_sNt), (Tio.99₇MOo.003)(0₂-s-tCsNt), (Tio.984MOo.016)(0₂-s-tC_sNt), (Ti₀.957MOo.043)(0₂- s_tC_sN_t), (Tio.9₇Wo.o3)(0₂__s_tC_sN_t), (Tio.9₅Wo.o5)(0₂__s_tC_sN_t), (Tio.99₆Vo.oo4)(0₂__s_tC_sN_t),

(Tio.984Vo.oi6)(0₂__s_tC_sN_t), or (Ti₀.97oVo.o3)(0₂._s.tC_sN_t).

26. The heterogeneous material of claim 16, wherein the n-type semiconductor comprises (Tii._rM_r)(0₂._s._tC_sN_t), wherein:

M is Sn;

r is from 0 to 0.25;

s is from 0.001 to 0.1 ; and

t is from 0.001 to 0.1 .

27. The heterogeneous material of claim 26, wherein r is greater than 0.

28. The heterogeneous material of claim 26, wherein r is 0, and the semiconductor comprises a rutile phase and an anatase phase.

29. The heterogeneous material of claim 16, wherein the n-type semiconductor is a tin oxide.

30. A method of decomposing a chemical compound, comprising exposing the chemical compound to a photocatalyst comprising the homogeneous material of claim 1 in the presence of light.

31 . The method of claim 30, wherein the chemical compound is a pollutant.

32. A method of killing a microbe, comprising exposing the microbe to a photocatalyst comprising the homogeneous material of claim 1 in the presence of light.