CN112795926A - Nano composite film material and application thereof - Google Patents

Nano composite film material and application thereof Download PDF

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Publication number
CN112795926A
CN112795926A CN202011551585.8A CN202011551585A CN112795926A CN 112795926 A CN112795926 A CN 112795926A CN 202011551585 A CN202011551585 A CN 202011551585A CN 112795926 A CN112795926 A CN 112795926A
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tio
cofe
cufe
nano composite
photo
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王宁
王静
刘梦楠
段继周
侯保荣
戈成岳
张冉
舒向泉
贺永鹏
林建康
乔泽
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Institute of Oceanology of CAS
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/12—Electrodes characterised by the material
    • C23F13/14—Material for sacrificial anodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • C01G23/08—Drying; Calcining ; After treatment of titanium oxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/26—Anodisation of refractory metals or alloys based thereon

Abstract

The invention relates to a nano composite film photo-anode material for photoelectrochemical cathodic protection, in particular to a nano composite film prepared by a hydrothermal method and a photo-reduction methodA film-combining material and preparation and application thereof. Depositing ferrate tetroxide and Ag nanoparticles on TiO by using a hydrothermal method and a photoreduction method2Forming Ag/ferrate tetroxide/TiO on the surface of the nanowire2A nanocomposite film photo-anode material; wherein the ferrate tetraoxide is CoFe2O4Or CuFe2O4. When the composite film is used as a photo-anode material for cathodic protection, compared with TiO2As for the material, the utilization rate of visible light and the separation rate of photo-generated carrier pairs are obviously improved, the electrode potential of 304 stainless steel is reduced, the corrosion rate is reduced, and TiO is effectively improved2Cathodic protection performance on 304 stainless steel.

Description

Nano composite film material and application thereof
Technical Field
The invention relates to a nano composite film photo-anode material for photoelectrochemical cathodic protection, in particular to a nano composite film material (Ag/CoFe) prepared by a hydrothermal method and a photo-reduction method2O4/TiO2And Ag/CuFe2O4/TiO2Composite membrane photoanode), and preparation and application thereof.
Background
Under the era background of rapid development of economic globalization, ocean economy increasingly becomes an important field for competition of various countries. The marine environment is an extremely complex corrosive environment, seawater is a strong electrolyte solution, the temperature, salinity, dissolved oxygen concentration, pH value, flow rate, marine organisms and the like of the seawater are all important factors influencing corrosion, the marine environment is far more corrosive than a land environment, and the corrosion problem of the marine is also an inevitable problem in marine development and construction. The traditional steel structure anticorrosion means needs a large amount of sacrificial anode materials or provides a large amount of power, and the development of marine industry is difficult to meet. Researches find that the novel photoelectrochemistry cathode protection technology has the advantages of strong operability, cleanness, resource saving and no electric energy consumption in the material anticorrosion aspect. The technology is to coat the semiconductor material or connect the semiconductor material to the protected metal by using a lead, when the semiconductor material is irradiated by light with energy higher than the forbidden band width, electrons in the valence band are excited to be transferred to the lead and then transferred to the metal substrate, so that the metal substrate is changed into an electron-rich state, and the potential of the electron-rich state is more negative than the corrosion potential, thereby protecting the metal from corrosion.
TiO2The material has high photoelectric conversion efficiency, stable chemical performance, no toxicity and harmlessness, and is widely applied to the field of photoelectrochemical cathode protection. However, TiO2The band gap is wider (3.2eV), only ultraviolet light with the wavelength less than 378nm can be absorbed, and the utilization rate of visible light is low; the photo-excited carrier pair is easy to compound, and the utilization rate of photo-generated electrons is low; under dark conditions, TiO2It cannot generate photo-generated electrons and provide photoelectrochemical cathodic protection for metals. The semiconductor material with narrow forbidden band width is made of TiO2Compounding, can effectively improve the utilization rate of light and enable TiO to be2The absorbed light of (2) extends from the ultraviolet region to the visible region, enhancing its cathodic protection effect on metals. Therefore, finding a material with a narrow band gap to compound with it is to enhance TiO2The important research direction of photoelectric conversion performance.
Disclosure of Invention
The invention aims to provide a nano composite film material (Ag/CoFe) prepared by a hydrothermal method and a photoreduction method2O4/TiO2And Ag/CuFe2O4/TiO2Composite membrane photoanode), and preparation and application thereof.
In order to achieve the purpose, the invention adopts the technical scheme that:
a nano-class composite film is prepared through hydrothermal method and photo-reduction method to deposit the nano-particles of ferrite tetroxide and Ag on TiO2Forming Ag/ferrate tetroxide/TiO on the surface of the nanowire2A nanocomposite film photo-anode material; wherein the ferrate tetraoxide is CoFe2O4Or CuFe2O4。
The method adopts a hydrothermal method to compound the ferrate tetroxide nano particles to the loaded TiO2Forming a film on the surface of the titanium sheet of the nanowire, and compounding Ag nanoparticles to ferrate tetroxide/TiO by adopting a photo-reduction method2And forming a film on the surface of the nano material to form the nano composite film photo-anode material.
The CoFe2O4/TiO2The nano composite membrane is dissolved to form precursor liquid by taking ferric trichloride hexahydrate, cobalt chloride hexahydrate and urea as solutes, deionized water as a solvent and acetylacetone as a stable additive; then loading TiO2Putting the titanium sheet of the nanowire in the precursor solution, and obtaining CoFe by a hydrothermal method2O4/TiO2The nano composite membrane material is characterized in that the molar concentrations of ferric trichloride, cobalt chloride and urea in the precursor solution are 5-10 mmol/L, 2.5-5.0 mmol/L and 45-90 mmol/L in sequence;
further, the following steps are carried out:
(1) sequentially dissolving 5-10 mmol/L ferric trichloride hexahydrate and 2.5-5.0 mmol/L cobalt chloride hexahydrate in 40-80 mL deionized water, dropwise adding 1-2 mL acetylacetone to increase system stability, slowly adding 45-90 mmol/L urea into the solution under a magnetic stirring state to form a precursor solution, uniformly mixing, and continuing to magnetically stir for 0.5-1 h to ensure that the solution is sufficiently uniform for later use;
(2) transferring the precursor solution to a hydrothermal reaction kettle, and adding TiO2Obliquely placing the nanowires in the reaction kettle, then placing the reaction kettle in an oven, setting the temperature to be 180-200 ℃, the reaction time to be 12-15 h, taking out the reaction kettle, naturally cooling to room temperature, respectively cleaning with deionized water and absolute ethyl alcohol for a plurality of times, and finally placing the reaction kettle in the ovenSetting the temperature at 60-80 ℃, and carrying out vacuum drying for 6-8 h to obtain CoFe2O4/TiO2A nanocomposite film.
The CuFe2O4/TiO2The nano composite membrane is formed by respectively dissolving copper acetate and potassium ferricyanide in deionized water, and then adding a copper acetate solution into potassium ferricyanide solution to be uniformly mixed to serve as a precursor solution; then loading TiO2Putting the titanium sheet of the nanowire in the precursor solution, and obtaining CuFe by a hydrothermal method2O4/TiO2A nanocomposite film material; wherein the concentration of copper acetate in the precursor solution is 30mmol/L, and the concentration of potassium ferricyanide is 20 mmol/L.
Further, the following steps are carried out:
(1) dissolving 0.060-0.120 g of copper acetate in 10-20 mL of deionized water to be recorded as solution A, and dissolving 0.196-0.392 g of potassium ferricyanide in 30-60 mL of deionized water to be recorded as solution B; then, stirring the two solutions for 10-20 min under an ice bath condition respectively to fully dissolve the two solutions, dropwise adding the solution A into the solution B under the ice bath magnetic stirring state, and magnetically stirring for 1-2 h to fully and uniformly prepare the solution A for later use;
(2) will support TiO2Obliquely putting a titanium sheet of the nanowire into the mixed solution (the solution overflows the titanium sheet), sealing the opening of the beaker, setting different reaction times for 2, 4, 6 and 8 hours respectively, taking out the titanium sheet, washing the titanium sheet with distilled water, and airing the titanium sheet at the temperature of 60 ℃; and finally, placing the mixture into a muffle furnace, setting the temperature to be 500-600 ℃, calcining for 1-1.5 h, cooling to room temperature, and taking out to obtain CuFe2O4/TiO2A nano composite film material.
CoFe prepared as above2O4/TiO2Nanocomposite film or CuFe2O4/TiO2The nano composite film is placed in 0.05-0.1 MAGNO3In the solution, a photo-reduction method is adopted to irradiate for 0.5-1 h by ultraviolet light, and then the solution is washed and dried to obtain Ag/CoFe2O4/TiO2A nanocomposite film photo-anode material;
the TiO is2The nano-wire is formed on a titanium sheet base by a one-step anodic oxidation methodObtaining TiO on the bottom2A nanowire.
The TiO is2The nanowire adopts a traditional double-electrode system, a titanium sheet is used as a working electrode, a platinum electrode is used as a counter electrode, the nanowire is clamped by an electrode clamp and then placed in 2-3M NaOH solution, and TiO is obtained on a titanium sheet substrate by a one-step anodic oxidation method2A nanowire.
The one-step anodic oxidation method comprises the steps of providing 1.3-2.5A direct current by a direct current power supply, carrying out anodic oxidation for 3-4 hours under the condition that the temperature of a solution is kept at 80-100 ℃, taking out a titanium sheet, sequentially cleaning the titanium sheet by using acetone, absolute ethyl alcohol and distilled water, naturally drying the titanium sheet, placing the titanium sheet in a muffle furnace at the set temperature of 450-600 ℃, calcining for 2-3 hours, and naturally cooling to obtain TiO on the surface of a substrate2A nanowire.
An application of a nano composite film material in photoelectrochemical cathodic protection as a photoanode material.
The nano composite film material is applied to photoelectrochemical cathode protection as a photoanode material under a dark state condition.
The application of the nano composite material as a photoelectrochemistry cathode protective film in inhibiting metal corrosion.
For the Ag/CoFe prepared above2O4/TiO2And Ag/CuFe2O4/TiO2The nano composite film photo-anode material is used for carrying out photoelectric performance and photoelectrochemical cathode protection tests, and a double electrolytic cell system consisting of a photo electrolytic cell and a corrosion electrolytic cell is adopted. 304 stainless steel and prepared Ag/CoFe2O4/TiO2And Ag/CuFe2O4/TiO2The nano composite material is respectively placed in the corrosion pool and the photo-anode pool. 3.5 wt% NaCl solution was placed in the corrosion cell, and 0.25M Na was placed in the photoelectrolysis cell2SO3As a hole trap, the naphthol film separates the electrolytes in the two cells and forms a closed loop. The reference electrode used in the experiment is a saturated calomel electrode, the electrochemical workstation is a P4000+, USA, PLS-SXE300C xenon lamp is used as a light source, and a 420 cut-off sheet is arranged at the outlet of the light source to acquire visible light to the surface of the anode. And (3) testing open circuit potential: before the experiment, a 304 stainless steel electrode is placed in 3.5 wt% NaCl solution to be soaked for 2 hours to reach an electrochemical stable state, the 304 stainless steel electrode is connected with a photoanode through a lead and then connected to a working electrode clamp of an electrochemical workstation, a saturated calomel electrode is connected with a reference electrode clamp, and the potential change of the 304 stainless steel relative to the saturated calomel electrode is observed by switching on and off light. Testing the photocurrent density: placing an ammeter with zero resistance on the surfaces of the photo-anode and the 304 stainless steel, short-circuiting the reference electrode and the counter electrode, testing the real current density of the reference electrode and the counter electrode under a non-polarized condition, connecting the 304 stainless steel electrode to the ground wire position of an electrochemical workstation, connecting the photo-anode with a working electrode clamp, and observing the change of the photo-current density on the surface of the 304 stainless steel by switching on and off light.
For the Ag/CoFe prepared above2O4/TiO2And Ag/CuFe2O4/TiO2And carrying out an ultraviolet-visible diffuse reflection test on the nano composite film photo-anode material to obtain an ultraviolet-visible diffuse reflection spectrum.
The basic principle of the invention is as follows:
using CoFe2O4The forbidden band width (1.13eV) is narrow, the utilization rate of visible light is high, and the stable chemical performance is realized; at the same time, CuFe2O4Has good magnetic and chemical stability, the forbidden band width is only 1.42eV, the utilization rate of visible light is high, and the TiO is a composite TiO2The ideal material of the material. CoFe2O4Composite TiO2Not only can effectively reduce pure TiO2The forbidden band width of TiO can be enlarged2The response range to visible light is widened, and the utilization rate of the visible light is improved. The deposition of Ag nanoparticles not only can improve TiO due to its surface Schottky effect2The utilization rate of light can also effectively reduce the recombination rate of photo-generated carrier pairs, improve the photoelectric conversion capability and effectively improve the photoelectrochemical cathode protection performance of the nano composite material. Thus, two kinds of ferrate tetroxide and Ag nano particles are respectively deposited on TiO by a hydrothermal method and a photoreduction method2Greatly enhances the TiO2The cathode protection effect on 304 stainless steel. When it is illuminatedWhen the Ag nano particles are shot to the surface of the nano composite material, the Ag nano particles have surface plasma resonance effect, and can quickly generate photo-generated carrier pairs, TiO2And CoFe2O4(CuFe2O4) The photo-generated electrons rapidly transit from the valence band to the conduction band position due to the excitation of light. The surface of the Ag nano particle has a lower Schottky barrier and CoFe due to the conduction band potential ratio of the Ag nano particle2O4(CuFe2O4) The potential of the conduction band is more negative, so that electrons on the conduction band of the Ag nano-particle can rapidly transit to CoFe2O4(CuFe2O4) On the guide belt; at the same time, due to TiO2Position ratio of conduction band of CoFe2O4(CuFe2O4) More negative, so that electrons generated by illumination excitation will be emitted by the TiO2Flow to CoFe2O4(CuFe2O4) A conduction band; and CoFe2O4(CuFe2O4) The photo-generated electrons reach the position of a conduction band by being excited by light, and the generated photo-generated electrons pass through TiO2The nano wire and the titanium matrix reach the surface of the 304 stainless steel, and the enriched electrons participate in the oxygen reduction process of the 304 stainless steel cathode, so that the cathode reaction is reduced, the 304 stainless steel anode reaction is simultaneously inhibited, and the purpose of protecting the 304 stainless steel cathode is achieved. Ag. CoFe2O4(CuFe2O4) With TiO2A heterojunction electric field is formed between the two electrodes, so that the photo-carrier pairs are more easily separated. In the presence of Na in the reaction system2SO3Hole traps, in which the holes generated are rapidly associated with Na2SO3Forming polysulfides. Due to the existence of the hole trapping agent, the secondary recombination rate of photo-generated carriers is reduced, the capability of the nano composite material for generating electrons under the excitation of light is further improved, and good cathodic protection can be provided for 304 stainless steel coupled with the nano composite material. Thus, Ag/CoFe under visible light irradiation2O4(CuFe2O4)/TiO2The photo-anode effectively reduces the corrosion rate of 304 stainless steel and shows good photo-cathode protection effect, namely through Ag and CoFe2O4(CuFe2O4) With TiO2The nano composite film can effectively improve the photoelectrochemical cathode protection effect of the film on metal.
The invention has the advantages that:
the invention uses CoFe2O4Or CuFe2O4Respectively mixing Ag nano particles with TiO2The nano wire is compounded, not only the TiO is enlarged2The response range to light effectively improves the utilization rate of sunlight, obviously reduces the recombination rate of photo-generated carrier pairs, reduces the electrode potential of metal, and obviously improves TiO2The cathode protection effect on 304 stainless steel. The method specifically comprises the following steps:
1. Ag/CoFe obtained by the invention2O4/TiO2(Ag/CuFe2O4/TiO2) The nano composite film photo-anode material forms a heterojunction electric field at the interface, so that TiO2The absorption range of light is expanded from an ultraviolet region to a visible region, the separation rate of photo-generated carrier pairs is greatly improved, the photoelectric conversion capability is enhanced, and the utilization rate of sunlight is effectively improved.
2. The surface of the nano composite film photo-anode material obtained by the invention is uniform and compact, and the CoFe is compounded2O4Or CuFe2O4And Ag nano particles have higher purity and no impurity is introduced.
3. The nano composite film photo-anode material can provide the best cathode protection for 304 stainless steel, and is prepared from Ag/CoFe relative to a saturated calomel electrode2O4/TiO2The electrode potential obtained by the nano composite material reaches-970 mV, and the corresponding photocurrent density reaches 450 mu A/cm2Is TiO214 times the photocurrent density of the nanowires; Ag/CuFe2O4/TiO2The electrode potential of the obtained nano composite material reaches-930 mV, and the corresponding photocurrent density reaches 475 muA/cm2Is TiO214.8 times of the photocurrent density of the nanowires; in the dark state, the nanocomposite can provide nearly 485mV cathodic protection for 304 stainless steel.
In conclusion, the invention adopts a hydrothermal method and a photoreduction method for preparationWhen the nano composite film is used as a photo-anode, TiO is greatly improved2The cathode protection effect on 304 stainless steel is an excellent anticorrosion protection material.
Drawings
FIG. 1 is a schematic diagram of Ag/CoFe preparation provided in example 1 of the present invention2O4/TiO2Schematic process of nanocomposite.
Fig. 2 is a schematic diagram of an experimental apparatus for testing the change of the photoelectric potential in the embodiments 1 and 2 of the present invention.
Fig. 3 is a schematic diagram of an experimental apparatus for testing the photo-induced current density according to examples 1 and 2 of the present invention.
FIG. 4 shows TiO compounds obtained under different NaOH concentrations according to example 1 of the present invention2Graph of open circuit potential and its photocurrent density of 304 stainless steel to which the nanowires were coupled.
FIG. 5 shows TiO obtained at different NaOH reaction times according to example 1 of the present invention2Graph of open circuit potential and its photocurrent density of 304 stainless steel to which the nanowires were coupled.
FIG. 6 shows TiO compounds obtained under different NaOH concentrations according to example 1 of the present invention2Nanowire Scanning Electron Micrographs (SEM) with 1M (a, b) NaOH concentration, 2M (c, d) NaOH concentration, and 3M (e, f) NaOH concentration.
FIG. 7 shows TiO obtained at different NaOH reaction times according to example 1 of the present invention2Nanowire Scanning Electron Microscopy (SEM), NaOH reaction time 120min (a, b), NaOH reaction time 180min (c, d), and NaOH reaction time 240min (e, f).
FIG. 8 shows the coupling of 304 stainless steel with CoFe under visible light irradiation and dark state conditions provided in example 1 of the present invention2O4/TiO2Nanocomposite (a) and Ag/CoFe2O4/TiO2Graph of open circuit potential change of nanocomposite (b). Where the abscissa is time(s), the ordinate is electrode potential (vvs.sce), on indicates turning on the power supply, and off indicates turning off the light source.
FIG. 9 shows 304 stainless steel coupled CoFe under irradiation of visible light and in a dark state according to example 1 of the present invention2O4/TiO2Nanocomposite (a) and Ag/CoFe2O4/TiO2Graph of photocurrent density change of nanocomposite (b). Wherein the abscissa is time(s) and the ordinate is current density (. mu.A/cm)2) On means power on and off means light off.
FIG. 10 shows pure TiO provided in example 1 of the present invention2Nanowire, CoFe composite under optimal conditions2O4And Scanning Electron Micrographs (SEM) of the surface of Ag nanoparticles, in which pure TiO was used2(a,b)，CoFe2O4CoFe with reaction time of 9h2O4/TiO2Nanocomposite (c, d), CoFe2O4The reaction time is 9h, AgNO3CoFe prepared at a concentration of 0.1M2O4/TiO2Nanocomposite (e, f).
FIG. 11 is a diagram of CoFe as provided in example 1 of the present invention2O4Reaction time is 9h, AgNO3Ag/CoFe prepared at a concentration of 0.1M2O4/TiO2Elemental surface profiles of Ti (b), O (c), Co (d), Fe (e), and Ag (f) for nanocomposites.
FIG. 12 is a diagram of CoFe as provided in example 1 of the present invention2O4Reaction time is 9h, AgNO3Ag/CoFe prepared at a concentration of 0.1M2O4/TiO2The X-ray photoelectron spectrum (a) of the nano composite material, and XPS spectra of high-resolution Ti2p (b), O1s (c), Fe2p (d), Co2p (e) and Ag3d (f).
FIG. 13 is a prepared TiO provided in example 1 of the present invention2Nanowires (curve a), CoFe prepared under optimal conditions2O4/TiO2Nanocomposite film (curve b), Ag/CoFe2O4/TiO2Uv-visible diffuse reflectance pattern of the nanocomposite film (curve c).
FIG. 14 shows Ag/CoFe provided in example 1 of the present invention2O4/TiO2A photoelectrochemical corrosion resistance mechanism diagram of the nano composite material under the irradiation of visible light.
FIG. 15 is a schematic diagram of Ag/CuFe preparation process provided in example 2 of the present invention2O4/TiO2Schematic process of nanocomposite.
FIG. 16 shows that CuFe is present in the dark state under visible light irradiation in example 2 of the present invention2O4304 stainless steel coupling CuFe when hydrothermal reaction time is different2O4/TiO2Nanocomposite film (a) and AgNO 3304 stainless steel coupling Ag/CuFe with different concentrations2O4/TiO2Open circuit potential change pattern of the nanocomposite film (b). Wherein the abscissa is time(s), the ordinate is electrode potential (V vs. sce), on indicates turning on the power supply, and off indicates turning off the light source.
FIG. 17 shows CuFe under the irradiation of visible light and in the dark state as provided in example 2 of the present invention2O4304 stainless steel coupling CuFe when hydrothermal reaction time is different2O4/TiO2Nanocomposite film (a) and AgNO 3304 stainless steel coupling Ag/CuFe with different concentrations2O4/TiO2Graph of photocurrent density change of the nanocomposite film (b). Wherein the abscissa is time(s) and the ordinate is current density (. mu.A/cm)2) On means power on and off means light off.
FIG. 18 shows pure TiO provided in example 2 of the present invention2Nanowire, composite CuFe under optimal conditions2O4Ag nanoparticles Scanning Electron Microscopy (SEM), in which pure TiO was used2Nanowire (a, b), CuFe2O4CuFe prepared when reaction time is 6h2O4/TiO2Nanocomposite (c, d), CuFe2O4The reaction time is 6h, AgNO3Ag/CuFe prepared at a concentration of 0.1M2O4/TiO2Nanocomposite (e, f).
FIG. 19 is a schematic view of a modified CuFe film provided in example 2 of the present invention2O4Reaction time is 6h, AgNO3Ag/CuFe prepared at a concentration of 0.1M2O4/TiO2The nanocomposite material has a distribution of Ti (b), O (c), Cu (d), Fe (e) and Ag (f) elements on the surface.
FIG. 20 is a schematic view of a modified CuFe film obtained in example 2 of the present invention2O4Reaction time is 6h, AgNO3Ag/CuFe prepared at a concentration of 0.1M2O4/TiO2The X-ray photoelectron spectrum (a) of the nano composite material, and XPS spectra of high-resolution Ti2p (b), O1s (c), Fe2p (d), Cu2p (e) and Ag3d (f).
FIG. 21 is a prepared TiO provided in example 2 of the present invention2Nanowire (curve a), CuFe prepared under optimal conditions2O4/TiO2Nanocomposite film (Curve b) and Ag/CuFe2O4/TiO2Uv-visible diffuse reflectance pattern of the nanocomposite film (curve c).
FIG. 22 shows Ag/CuFe according to example 2 of the present invention2O4/TiO2A photoelectrochemical corrosion resistance mechanism diagram of the nano composite material under the irradiation of visible light.
Detailed Description
The invention is further illustrated with reference to the following examples and figures, without thereby restricting the content of the invention.
The present invention utilizes metal salts (e.g., CoFe) having very good magnetic stability and/or chemical properties2O4Or CuFe2O4) Not only has high utilization rate to visible light, but also has the forbidden band width of only 1.13-1.42eV, and the material is compounded to TiO2The nano-wire surface can widen the absorption range of light and increase the utilization rate of light. The deposition of Ag nano particles can not only improve the utilization rate of light, but also effectively reduce the recombination rate of photo-generated carrier pairs due to the surface Schottky effect, enhance the photoelectric conversion capability and improve the photoelectrochemical cathode protection performance of the nano composite material.
The composite membrane structure of the invention is CoFe2O4Or CuFe2O4And Ag nanoparticles deposited on TiO2On the surface of the nanowire. The nano composite film photo-anode material forms a heterojunction electric field at the interface, so that TiO is enabled to be2The absorption range of light is expanded from ultraviolet region to visible region, and when the material is used as photoanode material for cathodic protection, the material is compared with TiO2As for the material, the separation rate of photo-generated carrier pairs is greatly improved, the photoelectric conversion capability is enhanced, and the photoelectric conversion efficiency is effectively improvedThe utilization rate of sunlight obviously reduces the electrode potential of 304 stainless steel, reduces the corrosion rate and enhances the protection effect of photoelectrochemistry cathodes.
Furthermore, the invention combines the advantages of narrow band gap of metal salt, surface Schottky effect of Ag nano particles and photogenerated carriers in TiO2The characteristic of fast transmission in the nanotube is combined, so that not only TiO is expanded2The response range to light effectively improves the utilization rate of sunlight, obviously reduces the recombination rate of photo-generated carrier pairs, reduces the electrode potential of metal, and obviously improves TiO2The cathode protection effect on 304 stainless steel can be used in the field of cathode protection of metal materials.
Example 1
Ag/CoFe2O4/TiO2The preparation of the nano composite film photo-anode material (see figure 1) comprises the following steps:
pretreatment of a titanium substrate: firstly, cutting a titanium sheet with the purity of 99.9 percent and the thickness of 0.1mm into the size of 30mm multiplied by 10mm, and then polishing each surface for 100 times by 2500-mesh sand paper to be used as a growth substrate of the composite film; secondly, sequentially ultrasonically cleaning the sample by using acetone, absolute ethyl alcohol and distilled water for 10min, 10min and 30min respectively, and drying for later use; thirdly, the titanium sheet is put into the mixed solution (the volume ratio is NaOH: Na) at the temperature of 85 DEG C2CO3：H2Soaking in O-5: 2:100) for 90min, taking out, and cleaning with distilled water; finally, in HF solution (volume ratio of HF: H)2Etching for 1min in the ratio of O to 1:5), taking out, sequentially cleaning with acetone, absolute ethyl alcohol and distilled water, and drying for later use.
TiO2Preparing the nano wire: preparing TiO on the surface of a titanium sheet by a one-step anodic oxidation method2A nanowire. The anode oxidation adopts a traditional double-electrode system, a titanium sheet is used as an anode, and a platinum electrode is used as a counter electrode. Firstly, a titanium sheet is clamped by an electrode clamp and is respectively put into 400mL of NaOH solution, the concentration of the NaOH solution is set to be 1M, 2M and 3M, the current of a direct current power supply is regulated to be stabilized at about 1.3A, the solution temperature is kept at 80 ℃, anodic oxidation is carried out at different times, the reaction time is respectively set to be 120min, 180min and 240min,then taking out the titanium sheet, sequentially cleaning the titanium sheet with acetone, absolute ethyl alcohol and distilled water, naturally airing the titanium sheet for later use, finally placing the titanium sheet in a muffle furnace, setting the temperature at 450 ℃, calcining the titanium sheet for 120min, taking out the titanium sheet and placing the titanium sheet in a dust-free dryer for later use, thus obtaining TiO prepared under different NaOH concentrations (shown in figure 6) and different anodic oxidation times (shown in figure 7) on the surface of the titanium sheet2A nanowire.
TiO prepared under different NaOH concentrations and different anodic oxidation times2The performance of the nano-wire is characterized, and the result shows that when the concentration of NaOH is 2M and the anodic oxidation time is 180min, the obtained TiO2The protection effect of the nano wire on the 304 stainless steel cathode is optimal; then, the next operation is carried out when the NaOH concentration is 2M and the oxidation time is 180 min.
CoFe2O4/TiO2Preparing a nano composite film: firstly, dissolving 5mmol ferric trichloride hexahydrate and 2.5mmol cobalt chloride hexahydrate in 40mL water, dropwise adding 1mL acetylacetone to increase the stability of the system, slowly adding 45mmol urea into the solution under the magnetic stirring state, and continuing to magnetically stir for 30min after uniform mixing; secondly, the solution is taken and transferred into a reaction kettle, and TiO prepared when the NaOH concentration is 2M and the oxidation time is 180min is added2Obliquely placing the nanowires in the reaction kettle, placing the reaction kettle in an oven, setting the temperature at 180 ℃, and carrying out hydrothermal reaction at different times, wherein CoFe2O4Setting the hydrothermal reaction time to 3h, 6h, 9h and 12h, taking out the reaction kettle, cooling to room temperature, taking out the titanium sheet, and alternately cleaning with deionized water and absolute ethyl alcohol for several times; finally, setting the temperature in an oven at 60 ℃, and performing vacuum drying for 6h to obtain the CoFe2O4CoFe prepared under different hydrothermal reaction time2O4/TiO2A nanocomposite film.
For different CoFe2O4CoFe prepared under hydrothermal reaction time2O4/TiO2The nano composite film is subjected to performance characterization, and the result shows that the CoFe is obtained when CoFe is used2O4When the hydrothermal reaction time of (3) is 9h, the obtained CoFe2O4/TiO2Nanocomposite film pair 304The protection effect of the steel cathode is optimal; then in CoFe2O4The next operation is carried out when the hydrothermal reaction time is 9 h.
Ag/CoFe2O4/TiO2Preparing a nano composite film: CoFe obtained above was loaded with Ag nanoparticles by photo-reduction2O4/TiO2Rice composite film surface. The obtained CoFe2O4/TiO2Placing the nano composite film into AgNO with different concentrations3In solution, AgNO3The concentration of the solution was set to 0.01M, 0.05M, 0.1M and 0.2M. Irradiating with ultraviolet light for 30min, taking out sample, washing with deionized water, and naturally air drying to obtain different AgNO3Ag/CoFe prepared at concentration2O4/TiO2A nanocomposite film.
For different AgNO3Ag/CoFe prepared at concentration2O4/TiO2The performance of the nano composite film is characterized, and the result shows that when AgNO is used3When the concentration of the solution is 0.1M, the obtained Ag/CoFe2O4/TiO2The nano composite film has the best effect on the cathode protection of 304 stainless steel; then in AgNO3The next operation was carried out at a concentration of 0.1M.
For Ag/CoFe2O4/TiO2And (3) characterizing the nano composite film: for Ag/CoFe2O4/TiO2Characterization of the nanocomposite films mainly includes field emission scanning electron microscopy (FSEM), energy spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis). Wherein, the field emission scanning electron microscope adopts NOVANANOSE EM 450 produced by FEI company of America, the accelerating voltage is 1kV, the spot size is 2.0, a CBS probe is selected, and secondary electrons and back scattering electrons are received to analyze the appearance; the energy spectrum adopts OxFORD X-MaxN50 produced by Oxford instruments science and technology Limited, the accelerating voltage is 15kV, the spot size is 3.0, and qualitative and quantitative analysis is carried out by characterizing characteristic X rays; the X-ray photoelectron spectroscopy adopts ESCALB 250Xi produced by Thermo Fisher Scientific company in USA, and the analysis adopts contaminated carbon (-284.8 eV) as sample binding energy charge correction, the excitation power is 150W, and the excitation source is monochromatic Al K alpha (14)86.6eV), a fixed energy passing mode is adopted, the full scanning range is 0-1600eV, the energy passing is 50eV, the step width is 1.0eV, the narrow scanning energy passing is 20eV, and the step width is 0.05 eV; UV-visible diffuse reflectance Cary 5000, manufactured by Varian, USA, as BaSO4As background, the scan range is 10 ° -80 ° (see fig. 8, 9, 10).
For Ag/CoFe2O4/TiO2And (3) carrying out photoelectric performance test on the nano composite film:
pretreatment of 304 stainless steel: the 304 stainless steel used for the experiment had a composition (wt.%) of 0.08C, 1.86Mn, 0.72Si, 0.035P, 0.029S, 18.25Cr, 8.5Ni, and the remainder was Fe. 304 stainless steel of 10mm × 10mm × 10mm was cut out and sealed in epoxy resin, and the working surface of the electrode was 10mm × 10 mm. And (3) polishing the surface of the substrate by using 2400-mesh silicon carbide abrasive paper until the surface is smooth, cleaning the surface by using absolute ethyl alcohol, then carrying out ultrasonic treatment in water for 5min, and putting the substrate into a drying dish for later use.
Open circuit potential and photocurrent density testing: 304 stainless steel and prepared Ag/CoFe2O4/TiO2The nano composite material is respectively placed in the corrosion pool and the photo-anode pool. 3.5 wt% NaCl solution was placed in the corrosion cell, and 0.25M Na was placed in the photoelectrolysis cell2SO3As a hole trap, the naphthol film separates the electrolytes in the two cells and forms a closed loop. The reference electrode used in the experiment was a saturated calomel electrode, the electrochemical workstation was a P4000+, USA, PLS-SXE300C xenon lamp as the light source, and a 420 cut-off sheet was placed at the exit of the light source to capture visible light to the anode surface. And (3) testing open circuit potential: before the experiment, a 304 stainless steel electrode is placed in 3.5 wt% NaCl solution to be soaked for 2 hours to reach an electrochemical stable state, the 304 stainless steel electrode is connected with a photoanode through a lead and then connected to a working electrode clamp of an electrochemical workstation, a saturated calomel electrode is connected with a reference electrode clamp, and the potential change of the 304 stainless steel relative to the saturated calomel electrode is observed by switching on and off light (see figure 2). Testing the photocurrent density: and placing an ammeter with zero resistance on the surfaces of the photo-anode and the 304 stainless steel, short-circuiting the reference electrode and the counter electrode, and testing the real current density of the reference electrode and the counter electrode under the electrodeless condition. Connecting the 304 stainless steel electrode to an electrochemical workstationThe change of the photocurrent density on the surface of 304 stainless steel was observed by switching the light on and off at the ground position with the photoanode connected to the working electrode clamp (see fig. 3).
For TiO in example 12Analysis of the cathodic protection performance of 304 stainless steel by nanowires is shown in FIG. 4, which shows TiO produced at different NaOH concentrations 2304 stainless steel open circuit potential map (a) to which the nanowires are coupled and its corresponding photocurrent density map (b). As can be seen from the graph, TiO was found at a NaOH concentration of 2M2The cathode protection effect of the nano-wire to 304 stainless steel is the best, the potential of the nano-wire to the saturated calomel electrode reaches-375 mV, and the corresponding photocurrent density reaches 32 mu A/cm2。
For TiO in example 12Analysis of the cathodic protection performance of 304 stainless steel by the nanowire is shown in FIG. 5, which shows TiO obtained under different NaOH reaction time conditions 2304 stainless steel open circuit potential map (a) to which the nanowires are coupled and its corresponding photocurrent density map (b). As can be seen from the figure, when the NaOH reaction time is 180min, the obtained TiO2The cathode protection effect of the nano-wire to 304 stainless steel is the best, the potential of the nano-wire to the saturated calomel electrode reaches-375 mV, and the corresponding photocurrent density reaches 32 mu A/cm2。
In conclusion, in the anodic oxidation reaction process, when the NaOH concentration is 2M and the reaction time is 180min, the obtained TiO2The nano-wire has the best protection effect on the cathode of 304 stainless steel.
For TiO in example 12The morphology of the nanowires was analyzed, and FIG. 6 shows TiO obtained at different NaOH concentrations2Scanning Electron Micrographs (SEM) of nanowires. As can be seen from the figure, at a NaOH concentration of 2M, TiO is obtained at this time2The nano wires are clear and visible, the particle size is uniform, and the nano wires are connected with each other to form a nest shape; when the concentration of NaOH is 1M, due to the low concentration, only an obvious pit-shaped structure appears, and the line structure is slightly visible; when the concentration of NaOH is 3M, the concentration is higher, a coupling structure appears between the nanowires, the particle size of the wires is increased, and a tubular-like structure is presented. It can be seen that when the NaOH concentration is 2MObtained TiO2The nanowire morphology is best.
For TiO in example 12The morphology of the nanowires was analyzed and FIG. 7 shows the TiO obtained under different NaOH reaction time conditions2Scanning Electron Micrographs (SEM) of nanowires. When the reaction time is 180min, TiO2The particle size is uniform and clearly visible; when the reaction time is 120min, the nanowire is not completely formed due to the short reaction time and the large particle size; when the reaction time is 240min, the nanowires are mutually crosslinked due to the long reaction time, a tubular structure appears, and the nanowire structure becomes unclear. It can be seen that when the NaOH reaction time is 180min, the obtained TiO2The nanowire morphology is best.
In summary, in combination with the previous open circuit potential and photocurrent density tests, when the NaOH concentration is 2M and the reaction time is 180min, the obtained TiO was2The nanowire performance is optimal.
For Ag/CoFe in example 12O4/TiO2The cathodic protection performance of the nanocomposite film was analyzed, and fig. 8 shows a graph of the open circuit potential change of a 304 stainless steel coupled nanocomposite film under visible light irradiation and dark state conditions. Wherein, Panel (a) is CoFe2O4The effect of hydrothermal reaction time on open circuit potential, and (b) is AgNO during photoreduction3Influence of concentration on open circuit potential. As can be seen from the graph (a), CoFe was observed at the instant when the xenon lamp was turned on2O4/TiO2The open circuit potential of the nanocomposite is significantly reduced, indicating that CoFe2O4Is compounded to improve TiO2The cathodic protection effect of (1); at the moment of light closing, the open-circuit potential rises rapidly, and compared with a saturated calomel electrode, the open-circuit potential can reach-360 mV at most and is obviously lower than the open-circuit potential (-180mV) of 304 stainless steel, which indicates that the composite material can still provide cathodic protection for the 304 stainless steel in a dark state. It can also be seen from the figure that when CoFe2O4The potential reached-625 mV relative to the saturated calomel electrode at a reaction time of 9h, while the potentials at reaction times of 3, 6 and 12h were-500 mV, -550mV and-600 mV, respectively, from which it can be seen that the reaction time of 9h resultedCoFe2O4/TiO2The nanocomposite material provides the best cathodic protection for 304 stainless steel coupled thereto. As can be seen from graph (b), Ag/CoFe was observed at the moment when the xenon lamp was turned on after the deposition of Ag nanoparticles2O4/TiO2The open circuit potential of the 304 stainless steel coupled with the nano composite material is obviously reduced, and the open circuit potential is obviously lower than that of pure TiO2Nanowire, CoFe2O4/TiO2The potential of the nano composite material is more negative, which shows that the deposited Ag nano particles obviously improve TiO2The cathodic protection effect of (1); at the moment of light closing, the open-circuit potential rises rapidly, and compared with a saturated calomel electrode, the open-circuit potential can reach-620 mV at most but is obviously lower than the open-circuit potential (-180mV) of 304 stainless steel and CoFe2O4/TiO2The open circuit potential of the nanocomposite (-360mV) indicates that the composite can still provide very good cathodic protection for 304 stainless steel in the dark state. It can also be seen from the figure that when AgNO3At a concentration of 0.1M, the potential of the electrode reaches-970 mV relative to the saturated calomel electrode, compared with AgNO at other concentrations3A more negative electrode potential is achieved during compounding. It can be seen that when AgNO is used3Ag/CoFe obtained at a concentration of 0.1M2O4/TiO2The nanocomposite can provide the best cathodic protection for 304 stainless steel coupled thereto. The reason for this is that CoFe2O4Increase in reaction time, TiO2The deposition amount of the surface of the nanowire is gradually increased, so that the surface active sites are increased, and more CoFe is generated when visible light irradiates the surface of the material2O4Excited to generate electrons, the photo potential is reduced, but when the surface deposition is excessive, the excited CoFe2O4But the photoelectric conversion capability is reduced; after Ag nano particles are deposited on the surface, excited electrons can be rapidly transferred to the surface of 304 stainless steel due to the plasma resonance effect of the surface, so that a very good cathodic protection effect is generated, but when excessive surface deposition is caused, Ag particles can become binding points of photo-generated carrier pairs, so that the cathodic protection effect is reduced. In summary, when CoFe2O4The reaction time is 9h, AgNO3Ag/CoFe at a concentration of 0.1M2O4/TiO2The nanocomposite film provides the best cathodic protection for 304 stainless steel coupled thereto.
For Ag/CoFe in example 12O4/TiO2The cathodic protection performance of the nanocomposite film was analyzed, and fig. 9 shows a graph of the change in photocurrent density between 304 stainless steel and the nanocomposite material under visible light irradiation and in a dark state. Wherein, Panel (a) is CoFe2O4The effect of hydrothermal reaction time on photocurrent density, graph (b) is AgNO during photoreduction3The effect of concentration on photocurrent density. As can be seen from graph (a), CoFe was observed at the instant when the xenon lamp was turned on2O4/TiO2The photocurrent density of the nanocomposite rose rapidly, with a positive value, indicating that electrons flowed from the nanocomposite through the electrochemical workstation to the surface of 304 stainless steel. In the presence of composite CoFe2O4The photocurrent density was then compared to pure TiO2The nanowires are significantly enlarged. It can also be seen from the figure that when CoFe2O4When the reaction time is 9h, the photocurrent density reaches 238 mu A/cm2Is TiO2Nanowire generated photocurrent density (32 muA/cm)2) 7.4 times of; when the reaction time is 3, 6 and 12 hours, the potential is 145 mu A/cm2、180μA/cm2And 220. mu.A/cm2This is in full agreement with the test results for open circuit potential. As can be seen from graph (b), Ag/CoFe at the moment of switching on the lamp xenon2O4/TiO2The photocurrent density between the nano composite material and 304 stainless steel is obviously higher than that of pure TiO2And CoFe2O4/TiO2A nanocomposite material. When AgNO3At the concentration of 0.1M, the photocurrent density reached 450 muA/cm2Is TiO2Nanowire generated photocurrent density (32 muA/cm)2) 14 times of that of CoFe2O4/TiO21.9 times of the nanocomposite. The magnitude of the photocurrent density is indicative of the separation capability of the photocarrier pair. Due to Ag/CoFe2O4/TiO2The heterojunction structure is formed at the interface of the nano composite material, so that the photo-generated carriers are improvedThe separation capacity of the pair. In summary, when CoFe2O4Reaction time is 9h, AgNO3Ag/CoFe at a concentration of 0.1M2O4/TiO2The photocurrent density between the nanocomposite and 304 stainless steel was the greatest and consistent with the open circuit test results, which provides the best cathodic protection for the 304 stainless steel to which it was coupled.
For Ag/CoFe in example 12O4/TiO2The surface topography of the nanocomposite film was analyzed and FIG. 10 shows pure TiO2Nanowire, CoFe composite under optimal conditions2O4And Scanning Electron Micrographs (SEM) of Ag nanoparticles. FIGS. (a) and (b) show pure TiO prepared by one-step anodic oxidation2Nanowire, visible TiO2The surfaces of the nested nanowires are uniformly distributed, the nanowires penetrate layer by layer, the nanowire structures are mutually closed, and the pore diameters are uniform; FIGS. (c) and (d) are the composite CoFe at a reaction time of 9h2O4TiO of nanoparticles2Scanning electron micrograph shows that CoFe2O4Homogeneously composited to TiO2Surface, but also complex CoFe2O4The particle size of the nano particles is relatively uniform, the particle size is about 50nm, and closed pores of the titanium dioxide nano wires can still be seen in an enlarged view; graphs (e) and (f) are AgNO3Compounding to CoFe at a concentration of 0.1M2O4/TiO2In the scanning electron microscope image of the nano composite material, compared with the images (c) and (d), Ag nano particles are obviously deposited on the surface of the composite material, the distribution is relatively uniform, and the diameter is about 10 nm. As described above, CoFe2O4And Ag nanoparticles to TiO2In a "nested" nanowire structure.
For Ag/CoFe in example 12O4/TiO2The surface morphology of the nanocomposite films was analyzed and FIG. 11 shows CoFe2O4Reaction time is 9h, AgNO3Ag/CoFe obtained at a concentration of 0.1M2O4/TiO2And (3) element surface distribution diagram of the nano composite film. As can be seen from the figure, the presence of Ti, O, Co, Fe and Ag elements is detected by the energy spectrum. FIG. (a) shows that the elements Ti and O are contained in the largest amounts, Co, Fe and AThe g content is about the same, but it is significantly lower than the Ti, O content.
For Ag/CoFe in example 12O4/TiO2Surface states of the nanocomposite films were analyzed, and FIG. 12 shows CoFe2O4Reaction time is 9h, AgNO3Ag/CoFe was obtained at a concentration of 0.1M2O4/TiO2The X-ray photoelectron spectrum of the nano composite material, wherein the graph (a) is a full spectrum graph, and the graphs (b-f) are high-resolution spectrums. As can be seen from the graph (a), the nanocomposite detects absorption peaks of Ti, O, Co, Fe and Ag elements, proves that the five elements exist, the detection result is consistent with the energy spectrum detection, and the redundant peaks are carbon elements used as sample binding energy charge correction; FIG. b is a high resolution energy spectrum of Ti, the 2p orbital absorption peaks of Ti are respectively at 459.32 and 465eV, and the two absorption peaks correspond to Ti2p3/2And Ti2p1/2The two absorption peaks can prove that the compound state of the titanium is Ti4+Corresponding to this experiment should be TiO2The element Ti of (1); FIG. d is a high-resolution energy spectrum of Fe, in which the total number of absorption peaks in the 2p orbital is four, and the absorption peaks at 712 and 725eV correspond to Fe2p3/2And Fe2p1/2Orbitals, absorption peaks at 718 and 730eV originating from Fe3+(ii) a FIG. e is the high resolution spectrum of Co, the 2p orbital absorption peaks of Co are located at 787.5 and 804eV, and the two absorption peaks correspond to Co2p3/2And Co2p1/2The two peaks can prove that the main compound state of Co in the compound is Co2+(ii) a The graph (f) is a high resolution energy spectrum of Ag, the 3d orbital absorption peaks of the silver are respectively located at 368.2 eV and 374.5eV, and the two absorption peaks correspond to Ag3d5/2And Ag3d3/2The two peaks can prove that the Ag nano particles exist in a simple substance silver state. In conclusion, the composition of the composite material is mainly CoFe through X-ray photoelectron spectroscopy test2O4Ag and TiO2From this, CoFe can be further confirmed2O4And Ag nano particles are successfully compounded to TiO2On the surface of the nanowire.
For Ag/CoFe in example 12O4/TiO2The optical absorption of the nanocomposite film was analyzed, and fig. 13 shows pure TiO2Nanowires, CoFe produced under optimal conditions2O4/TiO2Nanocomposite, Ag/CoFe2O4/TiO2Ultraviolet-visible diffuse reflectance pattern of the nanocomposite. As can be seen from the figure, TiO2The absorption threshold of the nanowire is about 390nm, and the corresponding forbidden band width is 3.2eV, so that the TiO can be shown2The absorption of light is mainly concentrated in the ultraviolet region, and the absorption capacity of the light spectrum with the wavelength of more than 390nm is very weak; in TiO2Nanowire surface composite CoFe2O4After Ag nano particles are added, the absorption of light is expanded to a visible region, and meanwhile, the absorption of ultraviolet light by the nano composite material is obviously enhanced; in CoFe2O4/TiO2After the Ag nano particles are compounded on the surface, the absorption intensity and wavelength of light are not obviously increased, mainly because the surface plasmon resonance effect of the Ag nano particles is caused and the Ag nano particles cannot be like compounded CoFe2O4The TiO can be obviously improved as the same as the nano particles with narrow forbidden band width2Absorption wavelength and absorption intensity of the nanowires. As described above, in TiO2Nanowire surface composite CoFe2O4And after Ag nano particles are added, the optical absorption performance of the material is obviously enhanced, the absorption range of light is expanded from an ultraviolet region to a visible region, the utilization efficiency of light is increased, and the photoelectric conversion capability of the material is improved.
For Ag/CoFe in example 12O4/TiO2The action mechanism of the nano composite film is analyzed, and FIG. 14 shows Ag/CoFe2O4/TiO2A photoelectrochemical corrosion resistance mechanism diagram of the nano composite film under the irradiation of visible light. According to CoFe2O4Ag nanoparticles and TiO2Conduction band valence band potential, a possible corrosion mechanism diagram is presented. TiO when light is irradiated to the nanocomposite surface2And CoFe2O4The photo-generated electrons rapidly transit from the valence band to the conduction band position due to the excitation of light. Since Ag nanoparticles have surface plasmon resonance effect, canThe photo-generated carrier pair is generated rapidly, and the surface of the photo-generated carrier pair has relatively low Schottky energy barrier and conduction band potential ratio CoFe2O4The potential of the conduction band is more negative, so that electrons on the conduction band of the Ag nano-particle can rapidly transit to CoFe2O4A conduction band; at the same time, because of TiO2Is also at a position of the conduction band of CoFe2O4More negative, TiO2Electrons generated by light excitation will flow to CoFe2O4A conduction band; in addition, CoFe2O4The photo-generated electrons generated by the self-light-receiving excitation reach the self-conduction band position, and finally pass through TiO2The nano wire and the titanium matrix reach the surface of the 304 stainless steel, and the enriched electrons participate in the oxygen reduction process of the 304 stainless steel cathode, so that the cathode reaction is reduced, the 304 stainless steel anode reaction is simultaneously inhibited, and the purpose of protecting the 304 stainless steel cathode is achieved. Ag. CoFe2O4With TiO2A heterojunction electric field is formed between the two electrodes, so that the photo-carrier pairs are more easily separated. In the presence of Na in the reaction system2SO3A hole trapping agent, in which holes generated during the reaction can be rapidly mixed with Na2SO3Forming polysulfides. Due to the existence of the hole trapping agent, the secondary recombination rate of the photo-generated carrier pair is reduced, the capability of the nano composite material for generating electrons under the excitation of light is further improved, and good cathodic protection can be provided for 304 stainless steel coupled with the nano composite material.
Ag/CoFe obtained as described above2O4/TiO2Making TiO from nano composite film photo-anode material2The light absorption range of the composite material is enlarged from an ultraviolet region to a visible region, so that the composite material not only can inhibit the corrosion of metal, but also has excellent photoelectric conversion effect, can play a good photoelectric chemical cathode protection effect on 304 stainless steel as a photoanode, and can still maintain a certain cathode protection effect in a dark state.
Example 2
Ag/CuFe2O4/TiO2The preparation of the nanocomposite film photoanode material (see fig. 15) comprises the following steps:
pretreatment of a titanium substrate: first, a titanium sheet having a purity of 99.9% and a thickness of 0.1mm was cutCutting into 30mm × 10mm, and polishing each surface with 2500-mesh abrasive paper for 100 times to obtain a growth substrate of the composite film; secondly, ultrasonically cleaning the sample by using acetone, absolute ethyl alcohol and distilled water in sequence for 10min, 10min and 30min respectively, and drying for later use; thirdly, the titanium sheet is put into the mixed solution (the volume ratio is NaOH: Na) at the temperature of 85 DEG C2CO3：H2O is 5:2:100) soaking for 90min, taking out, and cleaning with distilled water; finally, in HF solution (volume ratio of HF: H)2Etching for 1min in the ratio of O to 1:5), taking out, sequentially cleaning with acetone, absolute ethyl alcohol and distilled water, and drying for later use.
TiO2Preparing the nano wire: rapid preparation of TiO on the surface of a titanium sheet by a one-step anodic oxidation method2A nanowire. The anode oxidation adopts a traditional double-electrode system, a titanium sheet is used as an anode, and a platinum electrode is used as a counter electrode. Firstly, clamping a titanium sheet by an electrode clamp, putting the titanium sheet into 400mL of 2M NaOH solution, regulating the current of a direct current power supply to be stabilized at about 1.3A, keeping the temperature of the solution at 80 ℃, carrying out anodic oxidation for 180min, taking out the titanium sheet, sequentially cleaning the titanium sheet by acetone, absolute ethyl alcohol and distilled water, naturally airing the titanium sheet for later use, finally putting the titanium sheet into a muffle furnace, setting the temperature at 450 ℃, calcining the titanium sheet for 120min, taking out the titanium sheet and putting the titanium sheet into a dust-free dryer for later use, thus obtaining TiO on the surface of the titanium sheet2Nanowires (see fig. 18(a) and (b)).
CuFe2O4/TiO2Preparing a nano composite film: dissolving 0.060g of copper acetate in 10mL of deionized water to be recorded as solution A, and dissolving 0.196g of potassium ferricyanide in 30mL of deionized water to be recorded as solution B; then, stirring the two solutions respectively for 10min under the ice bath condition to fully dissolve the two solutions, dropwise adding the solution A into the solution B under the ice bath magnetic stirring state, and magnetically stirring for 60min to fully and uniformly dissolve the two solutions; then loading TiO2Obliquely putting the titanium plate of the nanowire into the mixed solution (the solution overflows the titanium plate), sealing the opening of the beaker, and placing the sealed beaker in different CuFe2O4Carrying out hydrothermal reaction for 2h, 4h, 6h and 8h respectively, taking out the titanium sheet, washing with distilled water, and airing at 60 ℃; finally, the step ofPlacing in a muffle furnace, setting the temperature at 500 deg.C, calcining for 60min, cooling to room temperature, and taking out to obtain different CuFe2O4CuFe prepared under hydrothermal reaction time2O4/TiO2Nanocomposite film material (see fig. 18(c) and (d)).
For different CuFe2O4CuFe prepared under hydrothermal reaction time2O4/TiO2The nano composite film is subjected to performance characterization, and the result shows that when CuFe is used2O4When the hydrothermal reaction time is 6h, the obtained CuFe2O4/TiO2The nano composite film has the best effect on the cathode protection of 304 stainless steel; then in CuFe2O4The next operation is carried out when the hydrothermal reaction time is 6 h.
Ag/CuFe2O4/TiO2Preparing a nano composite film: ag nano particles are loaded on CuFe by adopting a photo-reduction method2O4/TiO2CuFe on the surface of the nano composite film2O4/TiO2Placing the nano composite materials in AgNO with different concentrations respectively3In solution, AgNO3Setting the concentration of the solution to 0.01M, 0.05M, 0.1M and 0.2M respectively, irradiating for 30min with ultraviolet light, taking out the sample, washing the surface with deionized water, and naturally drying to obtain different AgNO3Ag/CuFe prepared at concentration2O4/TiO2A nanocomposite film (see fig. 18(e) and (f))).
For different AgNO3Ag/CuFe prepared at concentration2O4/TiO2The performance of the nano composite film is characterized, and the result shows that when AgNO is used3When the concentration of the solution is 0.1M, the obtained Ag/CuFe2O4/TiO2The nano composite film has the best effect on the cathode protection of 304 stainless steel; then in AgNO3The next operation was carried out at a concentration of 0.1M.
For Ag/CuFe2O4/TiO2And (3) characterizing the nano composite film: for Ag/CuFe2O4/TiO2The characterization of the nano composite film mainly comprises a field emission scanning electron microscope (FSEM), an energy spectrum (EDS) and an X-ray photoelectricityDaughter spectrum (XPS) and ultraviolet-visible diffuse reflectance spectrum (UV-Vis). Wherein, the field emission scanning electron microscope adopts NOVANANOSE EM 450 produced by FEI company of America, the accelerating voltage is 1kV, the spot size is 2.0, a CBS probe is selected, and secondary electrons and back scattering electrons are received to analyze the appearance; the energy spectrum adopts OxFORD X-MaxN50 produced by Oxford instruments science and technology Limited, the accelerating voltage is 15kV, the spot size is 3.0, and qualitative and quantitative analysis is carried out by characterizing characteristic X rays; the X-ray photoelectron spectrum adopts ESCALB 250Xi produced by Thermo Fisher Scientific company in America, the analysis adopts contaminated carbon (-284.8 eV) as sample binding energy to charge correction, the excitation power is 150W, the excitation source is monochromatic Al K alpha (1486.6eV), a fixed energy-passing mode is adopted, the full-scanning range is 0-1600eV, the energy-passing is 50eV, the step width is 1.0eV, the narrow scanning energy-passing is 20eV, and the step width is 0.05 eV; UV-visible diffuse reflectance Cary 5000, manufactured by Varian, USA, as BaSO4As the background, the scanning range is 10-80 deg.
For Ag/CuFe2O4/TiO2And (3) carrying out photoelectric performance test on the nano composite film:
pretreatment of 304 stainless steel: the 304 stainless steel used for the experiment had a composition (wt.%) of 0.08C, 1.86Mn, 0.72Si, 0.035P, 0.029S, 18.25Cr, 8.5Ni, and the remainder was Fe. 304 stainless steel of 10mm × 10mm × 10mm was cut out and sealed in epoxy resin, and the working surface of the electrode was 10mm × 10 mm. And (3) polishing the surface of the substrate by using 2400-mesh silicon carbide abrasive paper until the surface is smooth, cleaning the surface by using absolute ethyl alcohol, then carrying out ultrasonic treatment in water for 5min, and putting the substrate into a drying dish for later use.
Open circuit potential and photocurrent density testing: 304 stainless steel and the prepared Ag/CuFe2O4/TiO2The nano composite material is respectively placed in the corrosion pool and the photo-anode pool. 3.5 wt% NaCl solution was placed in the corrosion cell, and 0.25M Na was placed in the photoelectrolysis cell2SO3As a hole trap, the naphthol film separates the electrolytes in the two cells and forms a closed loop. The reference electrode used in the experiment was a saturated calomel electrode, the electrochemical workstation was a P4000+, USA, PLS-SXE300C xenon lamp as the light source, and a 420 cut-off sheet was placed at the exit of the light source to capture visible light to the anode surface. Open circuit potentialAnd (3) testing: before the experiment, a 304 stainless steel electrode is placed in 3.5 wt% NaCl solution to be soaked for 2 hours to reach an electrochemical stable state, the 304 stainless steel electrode is connected with a photoanode through a lead and then connected to a working electrode clamp of an electrochemical workstation, a saturated calomel electrode is connected with a reference electrode clamp, and the potential change of the 304 stainless steel relative to the saturated calomel electrode is observed by switching on and off light (see figure 2). Testing the photocurrent density: and placing an ammeter with zero resistance on the surfaces of the photo-anode and the 304 stainless steel, short-circuiting the reference electrode and the counter electrode, and testing the real current density of the reference electrode and the counter electrode under the electrodeless condition. Then the 304 stainless steel electrode is connected to the ground position of the electrochemical workstation, the photo anode is connected with the working electrode clamp, and the change of the photocurrent density on the 304 stainless steel surface is observed by switching on and off the light (see figure 3).
For Ag/CuFe in example 22O4/TiO2The cathodic protection performance of the nanocomposites was analyzed and fig. 16 shows a graph of the open circuit potential change of 304 stainless steel coupled nanocomposites under visible illumination and dark conditions. Wherein, the diagram (a) is CuFe2O4The effect of hydrothermal reaction time on open circuit potential, and (b) is AgNO during photoreduction3Effect of concentration on nanocomposite open circuit potential. As can be seen from the graph (a), CuFe is observed at the moment of turning on the lamp2O4/TiO2The open circuit potential of the nanocomposite is significantly reduced, indicating that CuFe2O4The compounding of the nano particles improves TiO2The open circuit potential is maintained in a stable state, and at the moment, the generated photoproduction electrons and the electrons participating in cathodic protection consumption reach dynamic balance; at the moment of light-off, the open-circuit potential rises rapidly, but the potential is obviously lower than that of 304 stainless steel (-180mV), and compared with a saturated calomel electrode, the open-circuit potential can reach-380 mV at most, which shows that under the dark state condition, the nano composite material can still provide cathodic protection for 304 stainless steel, and the cathodic protection and CuFe can be provided2O4Has the energy storage effect. FIG. (a) shows CuFe at the same time2O4Influence of hydrothermal reaction formation time on open circuit potential when CuFe2O4Reaction time is 6h, relative toThe potential of the saturated calomel electrode reaches-665 mV, and the potentials with the reaction times of 2, 4 and 8h are obviously higher than 6h, so that CuFe obtained in the reaction time of 6h2O4/TiO2The nanocomposite can provide the best cathodic protection for 304 stainless steel coupled thereto. CuFe deposited on the surface of the nanowire along with the increase of reaction time2O4The active sites of the nano particles are increased, and the generated photo-generated electrons are increased. However, excessive deposition of nanoparticles can act as recombination sites for photocarrier pairs, and is not conducive to the generation of photogenerated electrons. As can be seen from the graph (b), Ag/CuFe was observed at the instant of turning on the lamp2O4/TiO2The open circuit potential of the nano composite material is obviously reduced, which shows that the TiO nano particles are obviously improved after being deposited2The cathodic protection effect of (1). At the moment of light closing, the open-circuit potential rises rapidly, and compared with a saturated calomel electrode, the open-circuit potential can reach minus 680mV at most and is obviously lower than the open-circuit potential (-180mV) of 304 stainless steel, which shows that under the dark state condition, the composite material can still provide cathodic protection for the 304 stainless steel, and shows that the energy storage effect of the nano composite material is good. After Ag particles are deposited on the surface, a heterojunction electric field is formed at the interface of the nano composite material, so that photo-generated electrons and holes are separated easily, and the yield of the photo-generated electrons is improved. Panel (b) shows AgNO at the same time3Influence of concentration on the open-Circuit potential when AgNO3At a concentration of 0.1M, the potential reached-930 mV relative to the saturated calomel electrode, which is more negative than the electrode potential at other concentrations, and it can be seen that when AgNO is used3Ag/CuFe obtained at a concentration of 0.1M2O4/TiO2The nanocomposite can provide the best cathodic protection for 304 stainless steel coupled thereto.
For Ag/CuFe in example 22O4/TiO2The cathodic protection performance of the nanocomposite was analyzed and fig. 17 shows the photocurrent density change between 304 stainless steel and the nanocomposite under visible light irradiation and dark state conditions. Wherein, diagram (a) is CuFe2O4The effect of hydrothermal reaction time on photocurrent density, and (b) is nitro AgNO during photoreduction3Concentration versus photocurrentThe effect of density. As can be seen from the graph (a), CuFe is generated at the instant of turning on the lamp2O4/TiO2The photocurrent density of the nanocomposite rose rapidly, with a positive value, indicating that electrons flowed from the nanocomposite through the electrochemical workstation to the surface of 304 stainless steel. In the presence of composite CuFe2O4The photocurrent density was then compared to pure TiO2The nanowires are significantly larger. FIG. (a) shows CuFe at the same time2O4Influence of hydrothermal reaction time on photocurrent density when CuFe2O4The reaction time is 6h, and the photocurrent density reaches 250 mu A/cm2Is TiO2Nanowire generated photocurrent density (32 muA/cm)2) 7.8 times of the total weight of the powder. As can be seen from the graph (b), Ag/CuFe was observed at the moment when the xenon lamp was turned on2O4/TiO2The photocurrent density between the nanocomposite and 304 stainless steel is significantly higher than that of pure TiO2And CuFe2O4/TiO2A nanocomposite material. When AgNO3At the concentration of 0.1M, the photocurrent density reached 475 muA/cm2Is TiO2Nanowire generated photocurrent density (32 muA/cm)2) 14.8 times higher, the photocurrent density obtained is significantly higher than under the other conditions. After Ag nano particles are deposited, due to the existence of a heterojunction electric field and the increase of semiconductor active sites, photo-generated electrons are obtained more in solution, and a larger photocurrent density can be obtained. In summary, when CuFe2O4Reaction time is 6h, AgNO3Ag/CuFe at a concentration of 0.1M2O4/TiO2The photocurrent density between the nanocomposite and 304 stainless steel is maximized, which provides the best cathodic protection for the 304 stainless steel to which it is coupled.
For Ag/CuFe in example 22O4/TiO2The surface topography of the nanocomposite was analyzed and FIG. 18 shows pure TiO2Nanowire, composite CuFe under optimal conditions2O4And an Ag nano particle surface electron microscope image. The diagrams (a) and (b) show pure TiO prepared by one-step anodic oxidation2Nanowire, visible TiO2The surface of the nest-shaped nano wire is uniformly distributed, and the nano wireThe structures are mutually closed, and the aperture is uniform; the reaction time is 6h and CuFe is compounded2O4TiO of nanoparticles2In the electron micrograph, CuFe is clearly observed from the image (d) magnified twenty thousand times2O4Homogeneously composited to TiO2Although CuFe on the surface2O4The amount of deposit was relatively large, and TiO still appeared2Closed pores of the nanowires; the graphs (e) and (f) are AgNO3Compounding to CuFe at a concentration of 0.1M2O4/TiO2Comparing the electron microscope images of the nano composite material with the images (c) and (d), the Ag nano particles are obviously deposited on the surface of the composite material and are distributed uniformly; in graph (f) there is a distinct small "bright spot" present, with a diameter of about 10 nm. In summary, CuFe2O4A nanoparticles to TiO2In a "nested" nanowire structure of nanowires.
For Ag/CuFe in example 22O4/TiO2The surface topography of the nanocomposites was analyzed and FIG. 19 shows the surface topography at CuFe2O4Reaction time is 6h, AgNO3The Ag/CuFe is obtained under the condition that the concentration is 0.1M2O4/TiO2Elemental areal distribution profile of the nanocomposite. The element surface distribution diagram can intuitively and qualitatively express the distribution and content of each element in the compound. As can be seen from the figure, the energy spectrum detects the existence of Ti, O, Cu, Fe and Ag elements; the contents of Cu, Fe and Ag are approximately the same, but the contents of Cu, Fe and Ag are obviously lower than those of Ti and O; the elements are distributed uniformly and indirectly reflect CuFe2O4And Ag nanoparticles in TiO2The distribution on the nano-wires is relatively uniform.
For Ag/CuFe in example 22O4/TiO2The surface states of the nanocomposites were analyzed and FIG. 20 shows the surface states at CuFe2O4Reaction time is 6h, AgNO3The concentration is 0.1M to obtain Ag/CuFe2O4/TiO2The X-ray photoelectron spectrum of the nano composite material, wherein the graph (a) is a full spectrum graph, and the graphs (b-f) are high-resolution spectrums. As can be seen from the full spectrum of the graph (a), Ti, O, Cu, Fe and Ag elements are detected in the nano composite materialThe absorption peak proves the existence of the five elements, the detection result is consistent with the energy spectrum detection, and the redundant peak is carbon element used as sample binding energy charge correction; FIG. b is a high resolution energy spectrum of Ti, the absorption peaks of 2p orbitals of Ti are respectively at 459.32 and 465eV, and the two absorption peaks correspond to Ti2p3/2And Ti2p1/2The two absorption peaks can prove that the valence of titanium is Ti4+Corresponding to this experiment should be TiO2Ti in (1); FIG. d is a high-resolution energy spectrum of Fe, in which the total number of absorption peaks in the 2p orbital is four, and the absorption peaks at 712 and 725eV correspond to Fe2p3/2And Fe2p1/2Orbitals, absorption peaks at 718 and 730eV originating from Fe3+The two peaks can prove that the main combination state of Fe in the compound is Fe3+(ii) a FIG. e is the high resolution energy spectrum of Cu, the 2p orbital absorption peaks of Cu are respectively located at 934.88 and 954.78eV, and the two absorption peaks correspond to Cu2p3/2And Cu2p1/2The two peaks can prove that the main compound state of Cu in the compound is Cu2+(ii) a The graph (f) is a high resolution energy spectrum of Ag, the 3d orbital absorption peaks of Ag are respectively located at 368.2 eV and 374.5eV, and the two absorption peaks correspond to Ag3d5/2And Ag3d3/2The two peaks can prove that the silver nanoparticles exist in the state of simple substance silver. In conclusion, the components of the composite compound are mainly Ag and CuFe through X-ray photoelectron spectroscopy test2O4And TiO2From this, CuFe can be further confirmed2O4And successful complexation of Ag nanoparticles to AgNO3The surface of the nanowire.
For Ag/CuFe in example 22O4/TiO2The optical absorption of the nanocomposites was analyzed and FIG. 21 shows pure TiO2Nanowires, CuFe prepared under optimal conditions2O4/TiO2Nanocomposite film, Ag/CuFe2O4/TiO2Ultraviolet-visible diffuse reflectance pattern of the nanocomposite film. As can be seen from the figure, TiO2The absorption of the nano-wire to light is mainly concentrated in an ultraviolet region, and the absorption to visible light is obviously reduced, which shows that TiO2The utilization rate of light is insufficient;in TiO2Nano wire surface composite CuFe2O4After Ag nano particles, the absorption of the nano composite material to light is expanded to a visible region, and the absorption to ultraviolet light is obviously enhanced, which is mainly benefited from CuFe2O4The forbidden band width is narrow, and the energy required for the electrons to jump from the valence band to the conduction band is larger than that of TiO2Small enough to cause an electron to be excited to transition from the valence band to the conduction band, although visible light is less energetic than ultraviolet light; in the presence of CuFe2O4/TiO2After the Ag nano particles are compounded on the surface, the absorption intensity and the wavelength of light are not obviously increased, and the main reason is caused by the surface plasma resonance effect of the Ag nano particles and can not be like compounding CuFe2O4The TiO can be obviously improved as the same as the nano particles with narrow forbidden band width2Absorption wavelength and absorption intensity of the nanowires. As described above, in TiO2Nano wire surface composite CuFe2O4And after Ag nano particles are added, the optical absorption performance of the material is obviously enhanced, the absorption range of light is expanded from an ultraviolet region to a visible region, the utilization rate of light is increased, and the photoelectric conversion capability of the material is improved.
For Ag/CuFe in example 22O4/TiO2The action mechanism of the nanocomposite is analyzed, and FIG. 22 shows Ag/CuFe2O4/TiO2A photoelectrochemical corrosion resistance mechanism diagram of the nano composite material under the irradiation of visible light. According to Ag, CuFe2O4And TiO2The potential distribution of the conduction band and the valence band provides a feasible corrosion resistance mechanism diagram. When light irradiates the surface of the nano composite material, the Ag nano particles have surface plasma resonance effect, so that photo-generated carrier pairs, TiO2And CuFe2O4The photo-generated electrons rapidly transit from the valence band to the conduction band due to the excitation of light. The Ag surface has a lower Schottky barrier, so that the conduction band potential is more negative than CuFe2O4The conduction band potential is increased, so that electrons on the conduction band of the Ag nano-particles can rapidly transit to CuFe2O4On the guide belt; and CuFe2O4Conduction band potential ratio TiO2The potential of the conduction band is more negative, soCuFe2O4And electrons on Ag conduction band are rapidly enriched to TiO2The photogenerated electrons in the process reach the surface of the 304 stainless steel through the titanium substrate, and the enriched electrons participate in the process of the oxygen reduction of the cathode of the 304 stainless steel, so that the anode reaction of the 304 stainless steel is inhibited, and the purpose of protecting the cathode of the 304 stainless steel is achieved. In the presence of Na in the reaction system2SO3Hole traps, in which process the generated holes can be rapidly associated with Na2SO3Forming polysulfides. The existence of the hole trapping agent reduces the opportunity of recombination of photogenerated electrons and holes, further improves the capability of the nano composite material for generating electrons, and can provide good cathodic protection for 304 stainless steel coupled with the nano composite material.
The Ag/CuFe of the invention2O4/TiO2Making TiO from nano composite film photo-anode material2The light absorption range of the composite material is enlarged from an ultraviolet region to a visible region, so that the composite material not only can inhibit the corrosion of metal, but also has excellent photoelectric conversion effect, can play a good photoelectric chemical cathode protection effect on 304 stainless steel as a photoanode, and can still maintain a certain cathode protection effect in a dark state.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (8)

1. A nano composite film material is characterized in that: depositing ferrate tetroxide and Ag nanoparticles on TiO by using a hydrothermal method and a photoreduction method2Forming Ag/ferrate tetroxide/TiO on the surface of the nanowire2A nanocomposite film photo-anode material; wherein the ferrate tetraoxide is CoFe2O4Or CuFe2O4。
2. The nanocomposite film material of claim 1, which isIs characterized in that: the method adopts a hydrothermal method to compound the ferrate tetroxide nano particles to the loaded TiO2Forming a film on the surface of the titanium sheet of the nanowire, and compounding Ag nanoparticles to ferrate tetroxide/TiO by adopting a photo-reduction method2And forming a film on the surface of the nano material to form the nano composite film photo-anode material.
3. The nanocomposite film material of claim 2, wherein: the CoFe2O4/TiO2The nano composite membrane is dissolved to form precursor liquid by taking ferric trichloride hexahydrate, cobalt chloride hexahydrate and urea as solutes, deionized water as a solvent and acetylacetone as a stable additive; then loading TiO2Putting the titanium sheet of the nanowire in the precursor solution, and obtaining CoFe by a hydrothermal method2O4/TiO2The nano composite membrane material is characterized in that the molar concentrations of ferric trichloride, cobalt chloride and urea in the precursor solution are 5-10 mmol/L, 2.5-5.0 mmol/L and 45-90 mmol/L in sequence;
the CuFe2O4/TiO2The nano composite membrane is formed by respectively dissolving copper acetate and potassium ferricyanide in deionized water, and then adding a copper acetate solution into potassium ferricyanide solution to be uniformly mixed to serve as a precursor solution; then loading TiO2Putting the titanium sheet of the nanowire in the precursor solution, and obtaining CuFe by a hydrothermal method2O4/TiO2A nanocomposite film material; wherein the concentration of copper acetate in the precursor solution is 30mmol/L, and the concentration of potassium ferricyanide is 20 mmol/L.
4. The nanocomposite film material of claim 3, wherein: CoFe prepared as above2O4/TiO2Nanocomposite film or CuFe2O4/TiO2The nano composite film is placed in 0.05-0.1 MAGNO3In the solution, a photo-reduction method is adopted to irradiate for 0.5-1 h by ultraviolet light, and then the solution is washed and dried to obtain Ag/CoFe2O4/TiO2A nano composite film photo-anode material.
5. Pressing rightThe nanocomposite film material of claim 1, wherein: the TiO is2The nano wire is TiO obtained on a titanium sheet substrate by a one-step anodic oxidation method2A nanowire.
6. Use of the nanocomposite film material of claim 1, wherein: the nano composite film material is applied to photo-anode material and photoelectrochemical cathode protection.
7. The use of the nanocomposite film material of claim 6, wherein: the nano composite film material is applied to photoelectrochemical cathode protection as a photoanode material under a dark state condition.
8. The use of the nanocomposite film material of claim 6, wherein: the application of the nano composite material as a photoelectrochemistry cathode protective film in inhibiting metal corrosion.
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