WO2017221136A1

WO2017221136A1 - Photocatalytic water splitting using substrate with porous frit

Info

Publication number: WO2017221136A1
Application number: PCT/IB2017/053636
Authority: WO
Inventors: Vikas NARAYAN; Atul Pant
Original assignee: Sabic Global Technologies B.V.
Priority date: 2016-06-22
Filing date: 2017-06-19
Publication date: 2017-12-28

Abstract

The disclosure concerns a photocatalytic reactor for the conversion of water to hydrogen and oxygen gases. A device includes a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane; and a photocatalyst disposed adjacent the membrane. The membrane includes a porous frit, and the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

Description

PHOTOCATALYTIC WATER SPLITTING USING SUBSTRATE

WITH POROUS FRIT

TECHNICAL FIELD

[0001] The disclosure relates to a photocatalytic reactor for water splitting, and more specifically, a photocatalytic reactor for enhancing photocatalytic reactions.

BACKGROUND

[0002] Photocatalytic water splitting refers to a radiation-induced conversion of water to its hydrogen and oxygen constituents. Given the relative abundance of water, the technique has become valued as a clean and economically feasible potential method of obtaining a renewable source of energy, hydrogen.

SUMMARY

[0003] Conventional photocatalytic reactors designed to produce hydrogen from water may suffer from low efficiency in converting incident solar energy directly to fuel cells. A system for more efficient water splitting via photocatalysis would provide various benefits. Aspects of the disclosure relate to a device comprising a housing having an inlet and an outlet and defining a channel, wherein a porous, fritted membrane is disposed within the channel and within which a photocatalyst is disposed.

[0004] Aspects of the present disclosure relate to a device comprising: a housing having an inlet and an outlet, wherein the housing defines a channel formed therein and disposed in fluid communication with the inlet and the outlet and wherein the housing is configured to allow fluid passage through the channel; a membrane disposed within the channel of the housing, the membrane configured to allow water flowing through the channel to pass through the membrane; and a photocatalyst disposed within the membrane. The membrane comprises a porous frit, and the water flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to convert the water to hydrogen and oxygen gases.

[0005] Other aspects of the present disclosure relate to a method for the photocatalytic splitting of water, the method comprising: directing a stream of water into the inlet of a housing defining a channel; causing the stream of water to flow across a substrate disposed within the channel; and allowing the stream of water to exit the housing via an outlet of the housing.. The substrate comprises a porous frit and a catalyst disposed therein. The flow of water across the substrate initiates the conversion of the water to hydrogen and oxygen gases.

[0006] In yet other aspects, the present disclosure relates to a device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel; and a catalyst disposed adjacent the membrane. The membrane is configured to allow fluid flowing through the channel to pass through the membrane, and the membrane comprises a porous frit. The fluid flowing through the channel passes through the porous frit of the membrane and contacts the catalyst to facilitate a reaction of the fluid.

Brief Description of the Drawings

[0007] FIG. 1 is a diagram of a planar photocatalytic reactor.

[0008] FIG. 2 is a cross-sectional diagram of a planar photocatalytic reactor.

[0009] FIG. 3 is a diagram of a coated, tubular photocatalytic reactor.

DETAILED DESCRIPTION

[0010] The efficiency of photocatalytic water splitting to generate hydrogen is often limited by the absorption of incident solar light at the desired photocatalyst. The absorption of solar energy is required to drive the generation of hydrogen and oxygen gases from water.

[0011] The overall reaction efficiency may be affected by the specific surface area of photocatalyst configuration within the reactor. Typically, two kinds of photocatalytic reactor designs dominate photocatalytic water splitting: slurry tube reactors and coated tube reactors. In a slurry tube reactor, the photocatalyst is dispersed or suspended throughout a fluid phase and the fluid phase is illuminated with the required light energy for water splitting. In a coated tube reactor, the photocatalyst is applied to the walls of the tube reactor. The coating results in little- to-no porosity at the catalyst and thus, a more effective absorption of incident light. While slurry tubes have a greater surface area throughout which the photocatalysis reaction may occur than do coated tubes, the high porosity of slurry tube reactors may result in elevated amounts of light scattering and transmission and thereby limit catalytic activity because of reduced absorption. Further, coated tubes generally have a lower specific surface area, also limiting the efficiency of the photocatalyst due to diminished mass transfer rates of the photocatalysis reaction. The photocatalytic reactor disclosed herein provides a photocatalyst configuration benefitting from a greater specific surface area as well as improved absorption of incident solar energy or light. [0012] According to the band theory of solid state physics, energy levels available for valence electrons of a crystalline solid may be quantized in discrete bands. Each discrete band may be separated by a region of forbidden energy, commonly denoted as a band gap. Bands filled or partially filled with electrons at ground level energy are valence bands, while empty higher energy bands are conduction bands. Conductor materials have continuous electronic energy states because their valence bands are either incompletely filled or overlapped with a conduction band; while insulating materials, or insulators, have a completely filled valence band and large band gap to the conduction band. The electronic structure of a semiconductor falls between that of a conductor and an insulator because valence band electrons can usually be excited to the energy levels known as band gaps which are forbidden energy. In an exemplary photocatalysis for water splitting, a semiconductor photocatalyst absorbs photon energy that is greater than the band gap of the photocatalyst. Electrons in the valence band of the

semiconductor are thus excited to the conductive band and leave electronic vacancies in the valance band. These electronic vacancies are referred to as holes. The conduction band electrons and holes may recombine with each other and release the energy as heat, or migrate to the catalyst surface and initiate redox reactions with water, which results in the generation of active radicals. Preferably, these photo-excited electrons and holes separating and migrating to the surface of the photocatalyst do so with little or no recombination of the electrons and holes. The adsorbed species, or the species accumulated on the surface of the catalyst, is reduced and oxidized by the photo-generated electrons and holes to produce hydrogen and oxygen gases at different surface reaction sites.

[0013] In one aspect, the present disclosure relates to a photocatalytic reactor having an enhanced surface area for the photocatalytic reaction to occur and improved absorption of the solar radiation when compared to an analogous coated or slurry tube photocatalytic reactor.

[0014] During a typical process of photocatalysis, an oxide semiconductor such as titanium oxide absorbs photons with an appropriate energy level (for example, at a wavelength shorter than 387 nanometers (nm) for anatase, a mineral form of titanium dioxide), causing them to become photo-excited. These generated electrons and holes can migrate to the solid surface of the semiconductor catalyst, thereby initiating a series of oxidation-reduction reactions. The oxidation-reduction reactions result in the dissociation of water to its hydrogen and oxygen components in a gaseous state. Photocatalysis, however, can suffer from a low overall reaction rate and low energy efficiency due to, for example, limited catalyst activity, catalyst

poisoning/fouling, low surface area, or a limited capacity of the photocatalyst to absorb photons. In an aspect, the device of the present disclosure may maximize the surface area available for reaction within a photocatalytic reactor. The capacity of the photocatalyst to deliver the energy necessary to drive the oxidation reduction reactions may be thereby improved.

[0015] In various aspects, the photocatalytic reactor disclosed herein improves the surface interaction between the water molecules for splitting and the surface of the photocatalyst. Generally, the photocatalyst generates electron-hole pairs by absorbing light and the water splitting reaction subsequently occurs on the surface of the photocatalyst. The amount of water molecules adsorbed on the photocatalyst surface may increase as the surface area of the photocatalyst increases. Thus, an increase in surface area can enhance the reaction of photo- excited electron holes with the photocatalyst substrate. An increase in the surface area of the photocatalyst may also form defect centers in the photocatalyst acting as electron-hole recombination centers resulting in water molecule reformation. As such, the larger the surface area, the faster the photocatalytic reaction. The photocatalytic reactor of the present disclosure improves this interaction of the water molecules and the electron hole pairs at the surface of the photocatalyst via the fritted membrane described herein. The porous frit provides a greater surface area interaction between the photocatalyst surface and the water molecules as they flow through the membrane of the reactor. Namely, the additional space generated by the dispersion of the photocatalyst on the porous frit provides more interaction sites for the surface of the photocatalyst with water molecules. This improved interaction enhances both the kinetics and mass transfer rates of the water splitting process.

[0016] In various aspects of the present disclosure, the photocatalytic reactor may comprise a housing having an inlet and an outlet. The housing may define a channel formed therein and be disposed in fluid communication with the inlet and the outlet. The housing may be configured to allow fluid passage through the channel. Within the channel, a membrane is disposed. The membrane maybe be water-permeable and thus may be configured to allow the passage of water through the channel. The membrane may comprise a porous frit having a photocatalyst disposed adjacent thereto. As used herein, "adjacent" may include on, in, integrated with, coated with, and the like. In addition, "adjacent" may include an intervening coating or layer between the photocatalyst and at least a portion of the membrane or frit. As water flows through the channel and the porous frit of the membrane, the photocatalyst disposed adjacent the membrane may be engaged thereby initiating conversion of the flowing water to its constituent hydrogen and oxygen gases. The porous frit of the membrane may increase the incidence of interaction between the surface of the photocatalyst and the molecules of water flowing through the membrane. [0017] In a particular aspect as shown in FIG. 1, the photocatalytic reactor 100 comprises a planar housing 102. As an example, the planar housing 102 defines a channel 104 (e.g., chamber) and may comprise an inlet 106 and an outlet 134. The inlet 106 and the outlet 134 may be separate ports or may be configured as a common port to control inlet and/or outlet of fluid into the channel 104. A header 108 may be disposed adjacent the planar housing 102. The header may 108 may abut the planar housing 102 along an edge or end of the planar housing 102. The header 108 may include a water feed port 110 and a gas withdrawal port 112 in fluid communication with the planar housing 102 and the channel 104 disposed therein. The water feed port 110 may be configured to receive water, or fluid, into the photocatalytic reactor 100. The gas withdrawal port 112 may be configured to allow withdrawal of gases generated during photocatalysis. It is understood that the gas withdrawal port 112 may be configured as an outlet port for various fluids, including an exiting flow from the outlet 134.

[0018] The channel 104 disposed within the planar housing 102 is in fluid

communication with the header 108 via the inlet 106 and/or the outlet 134 of the planar housing 102. A planar membrane 114 comprising a porous frit may be disposed within the channel 104. A photocatalyst 116 may be disposed adjacent the porous frit of the planar membrane 114, or adjacent a surface of the porous frit, to facilitate catalysis within the photocatalytic reactor 100. Each of the planar housing 102 and planar membrane 114 may be flat and each may be of a particular thickness. The planar housing 102 may have a flat polygonal figure of a similar size and shape to accommodate the planar membrane 114. For example, the planar housing 102 may comprise a plurality of walls to encompass the planar membrane 114. Regardless of the shape or thickness of the planar membrane 114 or the planar housing 102, the planar membrane 114 may be sized within the channel 104 of the planar housing 102 such that the planar housing 102 forms a border, or frame, encompassing the planar membrane 114 along its edge.

[0019] In various aspects of the present disclosure, the photocatalytic reactor 100 may be configured so that a stream of fluid 118, such as water, may flow into the water feed port 1 10 of the header, through the inlet 106 of the planar housing 102, and across the planar membrane 114. Incident light 120 at the housing, such as solar radiation, may engage the photocatalyst 116 and initiate the conversion of the stream of fluid 118 to its constituent gases. Upon exposure to sunlight, the water is heated thereby allowing properties of thermo-siphoning to facilitate water flow across the porous frit containing the photocatalyst 116 and water circulation throughout the photocatalytic reactor 100. As such, during operation, the photocatalytic reactor 100 may be oriented in a vertical position so that the header 108 is situated higher or above relative to the planar housing 102. The header 108 may be configured to siphon the generated constituent gases and direct the siphoned gases out of the gas withdrawal port 1 12. The header 108 may continuously withdraw these gases during exposure to light or may withdraw the gases at intervals.

[0020] In one aspect where the photocatalytic reactor is a component of a larger process or system, withdrawals may be adjusted as per the downstream operation. The water feed port may be configured to receive water into the photocatalytic reactor. The gas withdrawal port may be configured to allow withdrawal of gases generated during photocatalysis. In some aspects, the water feed port and the gas withdrawal port of the header may comprise a single port to introduce water and to remove gases as the processes of introduction and removal are independent processes. The planar membrane is spaced within the planar housing, both of which are perpendicular to the flow of the stream of fluid. The fluid stream may flow through the porous frit of the planar membrane in contact with the photocatalyst disposed adjacent the planar membrane. In further aspects, the header may be configured to deliver a slurry comprising the photocatalyst into the reactor.

[0021] FIG. 2 provides a cross-sectional view of the photocatalytic reactor 200. The planar housing 202 may comprise a plurality of walls to encompass the planar membrane 214 within the channel 204. As such, the planar housing 202 may form a border, or frame, encompassing the planar membrane 214 along one or more of its edges. The planar housing 202 encompassing the planar membrane 214 may form a first surface 222 and a second surface 224 of the planar membrane 214. In some examples of the present disclosure, the photocatalyst 216 may be disposed from the header 208 as a slurry within the porous frit of the planar membrane 214. In further examples, the photocatalyst may be disposed throughout the porous frit of the planar membrane 214 prior to operation of the photocatalytic reactor 200.

[0022] In one aspect, one or more interior surfaces of one or more walls 226, 228 of the planar housing 202 may be coated with a reflective material to fully utilize incident light 220 from an incident light source. Appropriate walls of the housing 202 may be coated with a reflective material such as aluminum. In a particular example, the planar housing 202 may include a reflective coating 230 disposed adjacent a planar housing wall 228 opposite the second surface 224 of the planar membrane 214.

[0023] The planar housing 202 of the photocatalytic reactor 200 may comprise a transparent material to accept the incident light 220 (e.g., solar light). During photocatalysis, the reactor 200 may be oriented such that a portion of the housing comprising a transparent material is oriented to allow the incident light 220 into the photocatalytic reactor 200. In some aspects, one or more walls 226, 228, or portions of walls, of the planar housing 202 may comprise the transparent material. As a specific example, a planar housing wall 226 opposite the first surface 222 of the planar membrane 214 may be a transparent material. In a further aspect, a containing wall 232 comprising a transparent material may be disposed adjacent the reflective coating 230 or the planar housing wall 228 opposite the second surface 224 of the planar membrane 214. The incident light 220 (e.g., solar light) may pass through the transparent planar housing wall 226, enter the channel 204, and thereby engage the photocatalyst 216 deposited at the planar membrane 210. The transparent material may be sufficiently translucent to allow the passage of incident light 220 into the channel 204 of the planar housing and to the planar membrane 214. An exemplary transparent material may include quartz.

[0024] In a further aspect, the photocatalytic reactor may comprise one or more tubular housings connected to a common header. FIG. 3 provides a schematic diagram of a single tubular housing of a tubular photocatalytic reactor 300 assembly. The tubular housing 302 may define a channel 304 and may include an inlet 306 and an outlet 334. The channel 304 may be in fluid communication with the inlet 306 and outlet 334 to enable fluid passage through the tubular housing 302. In some configurations, one or more of the inlet 306 and outlet 334 may be in fluid communication with a header (not pictured). As described herein, the header may be configured to supply water into the tubular housing or may be configured to siphon generated gases out of the photocatalytic reactor. A membrane 314 comprising a porous frit may be disposed within the channel 304 of the tubular housing 302. In various aspects, each of the tubular housing 302 and the membrane 314 may have a particular thickness. In one example, the membrane 314 has a planar configuration. The planar membrane 314 may be disposed at a longitudinal, interior cross section of the tubular housing 302 so that an interior surface 336 of the tubular housing 302 abuts the planar membrane 314. For example, the longitudinal cross section of the tubular housing 302 abuts a periphery of the planar membrane 314 disposed within the channel 304. That is, the planar membrane 314 may be disposed within the channel 304 so that the planar membrane 314 is oriented along an axis of the tubular housing 302 between the inlet 306 and the outlet 334. The configuration of the planar membrane 314 within the tubular housing 302 creates a first surface 322 and a second surface 324 of the planar membrane 314. A suitable photocatalyst 316 may be disposed adjacent the planar membrane 314. In one example, the photocatalyst 316 may be disposed at or within the porous frit of the planar membrane. In yet further examples, additional photocatalyst 316 may be disposed at the interior surface 336 of the tubular housing 302.

[0025] As noted herein, the photocatalytic reactor may comprise a plurality of tubular housings joined together and ending in a single header. In the tubular configuration the planar or frame housing instead comprises a plurality of tubular housings each of which is connected to a common header at an end and, if necessary, at both ends of the tubular housing. The header may be in fluid communication with one or more of the inlet and outlet of the tubular housing.

[0026] During operation of the photocatalytic reactor 300, a stream of fluid 318, such as water, may enter the tubular housing 302 via the inlet 306 flowing across and through the porous frit of the planar membrane 314 disposed within the channel 304 of the tubular housing 302. Incident light 320 entering the tubular housing 302 may engage the disposed photocatalyst 316 and initiate photocatalysis of the stream of fluid 318. The fluid, for example water, may be converted to its constituent gases, oxygen and hydrogen.

[0027] In some aspects, an external pump may be used to circulate water through the photocatalytic reactor. The pump may increase flow velocity across the porous frit and thereby facilitate greater photocatalysis. Where a pump is used, water may enter the photocatalytic reactor at a portion of the planar housing rather than through the header. The water may flow across the porous frit and empty into the header. From the header, the water flows by gravity down into the pump where the water can be recirculated into the photocatalytic reactor. The header may be configured to siphon generated gases continuously or at specified intervals.

[0028] In some aspects, prior to operation of the photocatalytic reactor the header may be configured to deliver a slurry comprising additional photocatalytic catalyst into the reactor. For example, the header may deliver a photocatalytic slurry in liquid phase into the reactor at the planar membrane. In a further example, the header may include multiple nozzles or other injection devices to disperse a solvent containing a photocatalytic compound or compounds in a downward direction into the reactor.

[0029] In some aspects, the housing of the photocatalytic reactor may comprise a material resistant to degradation in outdoor environments. The housing may comprise a metal or polymeric material. In various examples, the housing may comprise stainless steel, aluminum, or ultraviolet (UV) resistant plastics. In some aspects, walls or portions of walls of the housing may be sufficiently transparent to allow incident solar light to enter the photocatalytic reactor to initiate photocatalysis. The walls of the tubular housing may be transparent to permit solar light into channel and to the membrane. As an example, walls or portions of walls of the housing may comprise quartz.

[0030] The membrane disposed within the reactor may comprise a porous frit. As used herein, a porous frit may refer to a composition or material comprising smaller materials, such as granules or particulate or a powder, that are fused together to form a unitary phase having small pores or openings throughout. When the membrane is disposed within the channel of the housing of the reactor, openings throughout the porous frit may accommodate the passage of a fluid, such as water through the reactor. Further, the openings of the porous frit allow the photocatalyst to be disposed therein. In a specific example, the porous frit comprises glass.

[0031] In certain aspects, the porous frit may comprise a porous glass frit. The porous glass frit may include sintered glass, or silicon dioxide. The sintered glass may include granules/particulate of silicon dioxide fused together to form a porous composition. In various aspects of the present disclosure, the photocatalyst may be disposed within the pores of the fritted membrane. The porous frit of the membrane may provide a greater surface area for the reaction of the photocatalyst with the fluid flowing through the photocatalytic reactor. In some aspects, the amount of photocatalyst disposed within the porous frit can affect efficiency of the photocatalytic reaction. As an example, where a dispersion of photocatalyst appears to be visually thick throughout porous frit, photon absorption from the incident light may be improved.

[0032] In further aspects, the porous frit may comprise aluminum oxide (or, alumina). An alumina porous frit may be comprised of sintered alumina, such as for example, an alumina ceramic. The sintered alumina may comprise granules/particulate of aluminum oxide fused together to form a porous composition.

[0033] The porous frit may have a pore volume of greater than about 30 %. In some examples, the porous volume may be between about 30 % and 50 %, or between about 30 % and 70 %. Generally, the pore size of the porous frit may depend upon the nature of the fluid flowing there through. In aspects of the present disclosure, the porous frit may have a pore size so sized to allow passage of water through the pores. As an example, the pore size of the porous frit may be between about 100 microns (μπι) and about 500 μπι. Exemplary pore sizes may include about 150 μπι, 200 μπι, 250 μπι, 300 μπι, 350 μπι, 400 μπι, and about 450 μπι.

[0034] The porous frit may be of a suitable size and dimension to accommodate the introduction of the catalyst and to allow fluid passage in order for photocatalysis to occur. In various examples, the fritted membrane may have a particular thickness or depth. Accordingly, the thickness, of the fritted membrane may be so sized to allow a dispersion of the catalyst throughout the porous frit to increase interaction between the photocatalyst and water flowing through the frit. As an example, the thickness of the porous frit may range between 100 micrometers (μπι) and a few millimeters (mm). In a specific example, the thickness of the porous frit may be less than 10 mm.

[0035] In various aspects of the present disclosure, the photocatalyst may be disposed adjacent the fritted membrane. In some examples, the photocatalyst may be disposed adjacent or on the fritted membrane to facilitate the photocatalytic reaction. In further examples, the photocatalyst may be disposed within or inside the fritted membrane. As such, the photocatalyst may be disposed within the pores of the porous frit comprising the fritted membrane. In a particular example, the photocatalyst may be integrated with the porous frit of the fritted membrane. The foregoing configurations of the photocatalyst disposed adjacent the fritted membrane are exemplary and are not intended to be limiting.

[0036] Further, the photocatalyst may be disposed adjacent the porous frit in a number of ways. In one example, a liquid suspension or slurry comprising the catalyst may be passed through the porous frit to deposit the catalyst in the frit. The slurry -loaded frit may then be dried. Generally, the process of disposing the catalyst within the porous frit may depend upon properties of the catalyst itself. More specifically, the particle size of the catalyst as well as its light absorption and scattering coefficient may determine how the catalyst is deposited within the frit. In further aspects, these properties of the catalyst may also govern the selection of the porous frit to which the catalyst is to be added. In further aspects, the arrangement of the porous frit further enhances interaction at the photocatalyst surface by reducing the formation of gas bubbles generated by the water photolysis. Typically, these bubbles can diminish the interaction between the photocatalyst surface and the water molecules. The configuration of the fritted membrane of the present disclosure can alleviate these concerns because the flow of water across the porous structure of the membrane can dissipate these bubbles.

[0037] An appropriate photocatalyst according to the present disclosure includes catalysts that exhibit photoactivity upon illumination. Semiconductors represent a class of catalysts exhibiting such photoactivity upon illumination. In some aspects, the photocatalyst is a semiconductor. Semiconducting materials may be valuable photocatalysts because of their unique electronic structure falling between that of an electronic conductor and an insulator. According to the band-gap theory of solid state physics, semiconductors have valence band electrons that can be excited conduction when a certain amount of energy is absorbed. Based on the laws of photochemistry, only photons with energies greater than the band gap energy can cause excitation of valence band electrons and possible reactions. The excitement can generate the requisite electron hole pairs that drive the reaction at the surface of photocatalyst.

Semiconductors such as, for example, titanium dioxide, cadmium sulfide, zinc sulfide, and zirconia may be appropriate. Particularly useful semiconductors for photocatalysis comprise titanium dioxide with a platinum or palladium metal coating.

[0038] In a further aspect, the present disclosure relates to methods of producing hydrogen via photocatalytic splitting of water. The method may comprise directing a stream of water into the inlet of a housing defining a channel. The stream of water may be caused to flow across a substrate disposed within the channel. The substrate may comprise a porous frit, at which a photocatalyst is disposed thereupon. The flow of water across the substrate may initiate conversion of the water to hydrogen and oxygen gases. The water is allowed to exit the housing via an outlet.

[0039] The disclosed systems include at least the following aspects.

[0040] Aspect 1. A device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0041] Aspect 2. A device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed within the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0042] Aspect 3. A device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0043] Aspect 4. A device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate constituent gases of the flowing fluid.

[0044] Aspect 5. A device consisting essentially of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0045] Aspect 6. A device consisting essentially of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed within the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0046] Aspect 7. A device consisting essentially of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0047] Aspect 8. A device consisting essentially of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate constituent gases of the flowing fluid.

[0048] Aspect 9. A device consisting of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0049] Aspect 10. A device consisting of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed within the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0050] Aspect 11. A device consisting of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

[0051] Aspect 12. A device consisting of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a photocatalyst disposed on the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane, thereby engaging the photocatalyst and initiating a reaction to generate constituent gases of the flowing fluid. [0052] Aspect 13. The device of any of aspects 1-12, wherein each of the housing and the membrane has a planar configuration, and wherein the housing encompasses the membrane along a periphery of the planar membrane.

[0053] Aspect 14. The device of aspects 1-13, wherein the housing has a tubular configuration and the membrane has a planar configuration and wherein an interior, longitudinal cross-section of the tubular housing abuts a periphery of the membrane disposed within the channel.

[0054] Aspect 15. The device of any of aspects 1-5, wherein the housing forms a first surface and a second surface of the planar membrane.

[0055] Aspect 16. The device of any of aspects 1-7, wherein the membrane comprises glass.

[0056] Aspect 17. The device of any of aspects 1-7, wherein the membrane comprises sintered glass.

[0057] Aspect 18. The device of any of aspects 1-9, wherein the housing is configured to allow incident solar radiation into the channel.

[0058] Aspect 19. The device of any of aspects 1-9 , wherein the housing or a portion of the housing is transparent.

[0059] Aspect 20. The device of any of aspects 1-9, wherein the housing or a portion of the housing comprises a transparent material.

[0060] Aspect 21. The device of any of aspects 1-12, wherein the fluid comprises water.

[0061] Aspect 22. A method for photocatalytic splitting of fluid, the method comprising: directing a stream of fluid to flow across a substrate disposed within a channel, wherein the substrate comprises a porous frit, and wherein a catalyst is disposed within the channel; and allowing electromagnetic radiation to pass into the channel and radiate the stream of water, wherein the electromagnetic radiation facilitates a reaction between the catalyst and the stream of water to convert at least a portion of the water to hydrogen and oxygen gases.

[0062] Aspect 23. A method for the photocatalytic splitting of fluid, the method consisting essentially of: directing a stream of fluid to flow across a substrate disposed within the channel, wherein the substrate comprises a porous frit, and wherein a catalyst is disposed within the channel; and allowing electromagnetic radiation to pass into the channel and radiate the flow of water, wherein the electromagnetic radiation facilitates a reaction between the catalyst and the flow of water to convert at least a portion of the water to hydrogen and oxygen gases. [0063] Aspect 24. A method for the photocatalytic splitting of fluid, the method consisting of: directing a stream of fluid to flow across a substrate disposed within the channel, wherein the substrate comprises a porous frit, and wherein a catalyst is disposed within the channel; and allowing electromagnetic radiation to pass into the channel and radiate the flow of water, wherein the electromagnetic radiation facilitates a reaction between the catalyst and the flow of water to convert at least a portion of the water to hydrogen and oxygen gases.

[0064] Aspect 25. The method of aspect 14, wherein the stream of water is directed from a first portion of the substrate across a first surface of the substrate to a second portion of the substrate.

[0065] Aspect 26. The method of any of aspects 14-15, wherein the porous frit comprises glass.

[0066] Aspect 27. The method of any of aspects 14-16, wherein the substrate is at least partially permeable to the fluid.

[0067] Aspect 28. A device comprising: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a catalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane and contacts the catalyst to facilitate a reaction of the fluid.

[0068] Aspect 29. A device consisting essentially of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a catalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane and contacts the catalyst to facilitate a reaction of the fluid.

[0069] Aspect 30. A device consisting of: a housing having an inlet and an outlet; a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet; a membrane disposed within the channel, the membrane configured to allow fluid flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and a catalyst disposed adjacent the membrane, wherein the fluid flowing through the channel passes through the porous frit of the membrane and contacts the catalyst to facilitate a reaction of the fluid.

[0070] Aspect 31. The device of any of aspects 28-30, wherein each of the housing and the membrane has a planar configuration, and wherein the housing encompasses the membrane along a periphery of the planar membrane.

[0071] Aspect 32. The device of any of aspects 28-31, wherein the housing has a tubular configuration and the membrane has a planar configuration and wherein an interior, longitudinal cross-section of the tubular housing abuts a periphery of the membrane disposed within the channel.

[0072] Aspect 33. The device of any of aspects 28-32, wherein the housing forms a first surface and a second surface of the membrane.

[0073] Aspect 34. The device of any of aspects 28-33, wherein the membrane comprises glass.

[0074] Aspect 35. The device of any of aspects 28-34, wherein the housing is configured to allow incident solar radiation to pass into the channel.

[0075] Aspect 36. The device of any of aspects 28-35, wherein the fluid comprises water.

[0076] Aspect 37. The device of any of aspects 28-36, wherein the catalyst is a photocatalyst.

[0077] Aspect 38. The device of any of aspects 28-37, wherein the reaction comprises water splitting to generate hydrogen and/or oxygen.

[0078] Aspect 39. The device of any aspects 28-38, wherein the membrane is planar. fii J IIfi S

[0079] It is to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term "comprising" can include the embodiments "consisting of and "consisting essentially of." Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined herein.

[0080] Ranges can be expressed herein as from one value (first value) to another value (second value). When such a range is expressed, the range includes in some aspects one or both of the first value and the second value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0081] As used herein, the terms "about" and "at or about" mean that the amount or value in question can be the designated value, approximately the designated value, or about the same as the designated value. It is generally understood, as used herein, that it is the nominal value indicated ±10% variation unless otherwise indicated or inferred. The term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is "about" or "approximate" whether or not expressly stated to be such. It is understood that where "about" is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0082] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other aspects of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

[0083] The photocatalytic reactor need not have any particular shape and as indicated by the aspects described above, the instant disclosure is capable of many variations, which will be apparent to those having ordinary skill in the art. Therefore, it is intended that instant disclosure not be limited to the aspects described above, but rather include all forms within the scope of the claims that follow.

[0084] Unless otherwise stated to the contrary herein, all test standards are the most recent standard in effect at the time of filing this application. [0085] Each of the materials disclosed herein are either commercially available and/or the methods for the production thereof are known to those of skill in the art.

[0086] It is understood that the compositions disclosed herein have certain functions. Disclosed herein are certain structural requirements for performing the disclosed functions and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

[0087] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

Claims

What is claimed:

1. A device comprising:

a housing having an inlet and an outlet;

a channel formed in the housing in fluid communication with the inlet and the outlet, wherein the channel is configured to allow fluid passage between the inlet and the outlet;

a membrane disposed within the channel, the membrane configured to allow fluid

flowing through the channel to pass through the membrane, wherein the membrane comprises a porous frit; and

a photocatalyst disposed adjacent the membrane,

wherein the fluid flowing through the channel passes through the porous frit of the

membrane, thereby engaging the photocatalyst and initiating a reaction to generate hydrogen and oxygen gases.

2. The device of claim 1, wherein each of the housing and the membrane has a planar

configuration, and wherein the housing encompasses the membrane along a periphery of the planar membrane.

3. The device of claim 1, wherein the housing has a tubular configuration and the membrane has a planar configuration and wherein an interior, longitudinal cross-section of the tubular housing abuts a periphery of the membrane disposed within the channel.

4. The device of any of claims 1-3, wherein the housing forms a first surface and a second surface of the planar membrane.

5. The device of any of claims 1-4, wherein the membrane comprises glass.

6. The device of any of claims 1-5, wherein the housing is configured to allow incident solar radiation into the channel.

7. The device of any of claims 1-6, wherein the fluid comprises water.

8. A method for photocatalytic splitting of fluid, the method comprising:

directing a stream of fluid to flow across a substrate disposed within a channel, wherein the substrate comprises a porous frit, and wherein a catalyst is disposed within the channel; and

allowing electromagnetic radiation to pass into the channel and radiate the stream of water, wherein the electromagnetic radiation facilitates a reaction between the catalyst and the stream of water to convert at least a portion of the water to hydrogen and oxygen gases.

9. The method of claim 8, wherein the stream of water is directed from a first portion of the substrate across a first surface of the substrate to a second portion of the substrate.

10. The method of any of claims 8-9, wherein the porous frit comprises glass.

11. The method of any of claims 8-10, wherein the substrate is at least partially permeable to the fluid.

12. A device comprising:

a housing having an inlet and an outlet;

a membrane disposed within the channel, the membrane configured to allow fluid

a catalyst disposed adjacent the membrane,

membrane and contacts the catalyst to facilitate a reaction of the fluid.

13. The device of claim 12, wherein each of the housing and the membrane has a planar configuration, and wherein the housing encompasses the membrane along a periphery of the planar membrane.

14. The device of claim 12, wherein the housing has a tubular configuration and the

membrane has a planar configuration and wherein an interior, longitudinal cross-section of the tubular housing abuts a periphery of the membrane disposed within the channel.

15. The device of any of claims 12-14, wherein the housing forms a first surface and a

second surface of the membrane.

16. The device of any of claims 12-15, wherein the membrane comprises glass.

17. The device of any of claims 12-16, wherein the housing is configured to allow incident solar radiation to pass into the channel.

18. The device of any of claims 12-17, wherein the fluid comprises water.

19. The device of any of claims 12-18, wherein the catalyst is a photocatalyst.

20. The device of any of claims 12-19, wherein the reaction comprises water splitting to generate hydrogen and/or oxygen.