Bismuth vanadate-metal organic complex composite photoelectrode and preparation method and application thereof
阅读说明：本技术 一种钒酸铋-金属有机配合物复合光电极及其制备方法和应用 (Bismuth vanadate-metal organic complex composite photoelectrode and preparation method and application thereof ) 是由 熊贤强 艾成浩 梅优阳 张晓� 韩得满 李江山 程高飞 武承林 于 2021-10-18 设计创作，主要内容包括：本发明属于光电极技术领域,特别涉及一种钒酸铋-金属有机配合物复合光电极及其制备方法和应用。本发明提供的钒酸铋-金属有机配合物复合光电极,包括基底和负载在所述基底表面的BiVO-(4)-金属有机配合物复合薄膜,所述BiVO-(4)-金属有机配合物复合薄膜由BiVO-(4)-金属有机配合物颗粒构成；所述BiVO-(4)-金属有机配合物颗粒包括BiVO-(4)内核和包覆所述BiVO-(4)内核的金属有机配合物形成的外壳；所述金属有机配合物为Fe～(2+)-2,5-二羟基对苯二甲酸络合物。本发明提供的钒酸铋-金属有机配合物复合光电极具有结构稳定性高、光电化学性能优良且化学稳定性高的特点。(The invention belongs to the technical field of photoelectrodes, and particularly relates to a bismuth vanadate-metal organic complex composite photoelectrode as well as a preparation method and application thereof. The invention provides a bismuth vanadate-metal organic complex composite photoelectrode which comprises a substrate and BiVO loaded on the surface of the substrate 4 -a metal organic complex composite film, said BiVO 4 The-metal organic complex composite film is prepared from BiVO 4 -metal organic complex particles; the BiVO 4 The metal-organic complex particles comprise BiVO 4 A kernel and a BiVO coated 4 A shell formed by a metal organic complex of the inner core; the metal organic complex is Fe 2+ -2, 5-dihydroxyterephthalic acid complex. The invention provides bismuth vanadate-metal organic complex composite lightThe electrode has the characteristics of high structural stability, excellent photoelectrochemical performance and high chemical stability.)
1. The bismuth vanadate-metal organic complex composite photoelectrode comprises a substrate and BiVO loaded on the surface of the substrate4-a metal organic complex composite film, said BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles; the BiVO4The organometallic complex comprises BiVO4A kernel and a BiVO coated4A shell formed by a metal organic complex of the inner core;
the metal organic complex is Fe2+-2, 5-dihydroxyterephthalic acid complex.
2. The bismuth vanadate-metal organic complex composite photoelectrode according to claim 1, wherein the metal organic complex is in an amorphous structure.
3. According to claim 1The bismuth vanadate-metal organic complex composite photoelectrode is characterized in that BiVO4The particle size of the inner core is 100-200 nm; the thickness of the shell is 3-100 nm.
4. The bismuth vanadate-metal organic complex composite photoelectrode of claim 1, wherein the BiVO is4The thickness of the-metal organic complex composite film is 1-50 mu m.
5. The preparation method of the bismuth vanadate-metal organic complex composite photoelectrode according to any one of claims 1 to 4, comprising the following steps:
providing BiVO4Photoelectrode of said BiVO4The photoelectrode comprises a substrate and BiVO loaded on the surface of the substrate4Film of said BiVO4The film is made of BiVO4Particle formation;
mixing inorganic metal salt, organic ligand and solvent to obtain inorganic metal salt-ligand mixed solution; the inorganic metal salt comprises an inorganic ferrous salt; the organic ligand is 2, 5-dihydroxy terephthalic acid;
BiVO (bismuth oxide) is added4And immersing the photoelectrode in an inorganic metal salt-ligand mixed solution, and carrying out hydrothermal reaction to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
6. The method according to claim 5, wherein the inorganic ferrous salt comprises ferrous chloride, ferrous sulfate, or ferrous nitrate.
7. The method according to claim 5, wherein the molar ratio of the inorganic metal ion to the organic ligand in the inorganic metal salt-ligand mixture is 1: (2-3).
8. The method according to claim 5, wherein the concentration of the inorganic metal salt in the inorganic metal salt-ligand mixture is 8 to 50 mmol/L.
9. The preparation method according to claim 5, wherein the hydrothermal reaction is carried out at a temperature of 130-150 ℃ for 10-16 h.
10. The application of the bismuth vanadate-metal organic complex composite photoelectrode according to any one of claims 1 to 4 or the bismuth vanadate-metal organic complex composite photoelectrode obtained by the preparation method according to any one of claims 5 to 9 as a catalytic electrode in photoelectrocatalysis water oxidation reaction.
Technical Field
The invention belongs to the technical field of photoelectrodes, and particularly relates to a bismuth vanadate-metal organic complex composite photoelectrode as well as a preparation method and application thereof.
Background
The semiconductor photoelectrocatalysis water oxidation can combine the advantages of photocatalysis and electrocatalysis, and can decompose water into H under the conditions of a small amount of bias voltage and sunlight irradiation2And O2. At present, researchers have developed a variety of semiconductor photoanodes for semiconductor photoelectrocatalytic water oxidation, such as ZnO, Fe2O3、TiO2、WO3、CuWO4Or BiVO4. Wherein, the bismuth vanadate (BiVO) has a monoclinic structure4) The interest of researchers has been brought about by the narrow band gap (about 2.4eV) and the broad spectral absorption range.
There are still two key problems in realizing the industrial application of bismuth vanadate photoelectrode: the stability of bismuth vanadate is poor, dissolution corrosion is easy to occur in an alkaline solution, and light corrosion is easy to occur under illumination, so that the long-time stability of bismuth vanadate is greatly limited; the aqueous oxidation reaction at the bismuth vanadate/solution interface involves four electron transfer, which is extremely slow in kinetics, resulting in poor water splitting activity. In order to solve the two problems, one of the most common methods is to load an inorganic electrocatalyst on the surface of a bismuth vanadate electrode, such as FeOOH, CoPi, NiFe-LDH or NiOOH on the surface of the bismuth vanadate electrode, and the load of the inorganic electrocatalyst can reduce the alignment between the bismuth vanadate electrode and the solutionContact is carried out, so that chemical corrosion is reduced; meanwhile, the introduction of the inorganic electrocatalyst can reduce the activation energy of water oxidation, improve the interface charge transfer speed and further improve the water decomposition activity. However, the existing inorganic electrocatalysts (e.g. ShiY, YuY, YuY, et al. boosting Photoelectrochemical Water Oxidation Activity and Stablity of Mo-coped BiVO)4 through the Uniform Assembly Coating of NiFe–Phenolic Networks[J]ACS Energy Letters 2018. unsenderylett.8b00855.), the coating of bismuth vanadate by an inorganic electrocatalyst is uneven, ions in a solution are easy to permeate into a bismuth vanadate layer to generate chemical corrosion, and the structural stability is poor, so that the photoelectrochemical performance is poor.
Disclosure of Invention
In view of the above, the present invention provides a bismuth vanadate-metal organic complex composite photoelectrode and a preparation method thereof, and the bismuth vanadate-metal organic complex composite photoelectrode provided by the present invention has the characteristics of high structural stability, excellent photoelectrochemical properties and high stability.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
the invention provides a bismuth vanadate-metal organic complex composite photoelectrode, which comprises a substrate and BiVO loaded on the surface of the substrate4-a metal organic complex composite film, said BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles; the BiVO4The metal-organic complex particles comprise BiVO4A kernel and a BiVO coated4A shell formed by a metal organic complex of the inner core;
the metal organic complex is Fe2+-2, 5-dihydroxyterephthalic acid complex.
Preferably, the metal organic complex is in an amorphous structure.
Preferably, the BiVO4The particle size of the inner core is 100-200 nm; the thickness of the shell is 3-100 nm.
Preferably, the BiVO4The thickness of the-metal organic complex composite film is 1-50μm。
The invention also provides a preparation method of the bismuth vanadate-metal organic complex composite photoelectrode in the technical scheme, which comprises the following steps:
providing BiVO4Photoelectrode of said BiVO4The photoelectrode comprises a substrate and BiVO loaded on the surface of the substrate4Film of said BiVO4The film is made of BiVO4Particle formation;
mixing inorganic metal salt, organic ligand and solvent to obtain inorganic metal salt-ligand mixed solution; the inorganic metal salt comprises an inorganic ferrous salt; the organic ligand is 2, 5-dihydroxy terephthalic acid;
BiVO (bismuth oxide) is added4And immersing the photoelectrode in an inorganic metal salt-ligand mixed solution, and carrying out hydrothermal reaction to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
Preferably, the inorganic ferrous salt includes ferrous chloride, ferrous sulfate or ferrous nitrate.
Preferably, the molar ratio of the inorganic metal ions to the organic ligands in the inorganic metal salt-ligand mixed solution is 1: (2-3).
Preferably, the concentration of the inorganic metal salt in the inorganic metal salt-ligand mixed solution is 8-50 mmol/L.
Preferably, the temperature of the hydrothermal reaction is 130-150 ℃ and the time is 10-16 h.
The invention also provides an application of the bismuth vanadate-metal organic complex composite photoelectrode in the technical scheme or the bismuth vanadate-metal organic complex composite photoelectrode obtained by the preparation method in the technical scheme as a catalytic electrode in photoelectrocatalysis water oxidation reaction.
The invention provides a bismuth vanadate-metal organic complex composite photoelectrode, which comprises a substrate and BiVO loaded on the surface of the substrate4-a metal organic complex composite film, said BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles; the BiVO4The metal-organic complex particles comprise BiVO4A kernel and a BiVO coated4A shell formed by a metal organic complex of the inner core; the metal organic complex is Fe2+-2, 5-dihydroxyterephthalic acid complex.
In the invention, the BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles, said BiVO4The metal-organic complex particles comprise BiVO4A kernel and a BiVO coated4A shell formed by a metal organic complex of an inner core, the BiVO being relatively simple to mix4BiVO is caused by the core-shell structure of-metal organic complex particles4The binding force of the inner core and the shell formed by the metal organic complex is high, and BiVO is ensured4The inner core is tightly connected with the shell formed by the metal organic complex, and the BiVO is improved4The interface integrity of the shell formed by the inner core and the metal organic complex is beneficial to the synchronism and uniformity of the distribution of the bismuth vanadate and the metal organic complex, the corrosion loss of the bismuth vanadate is reduced, and the structural stability is improved; simultaneously, BiVO is also avoided4The gap between the inner core and the shell formed by the metal organic complex reduces the transfer resistance of a photogenerated hole and the recombination speed of a photogenerated carrier, thereby achieving the effects of reducing the overpotential of water decomposition, increasing the photocurrent density and improving the photostability. Moreover, the metal organic complex can passivate the surface state of the surface of the bismuth vanadate core and reduce the surface recombination rate of bismuth vanadate carriers, so that the concentration of photo-generated holes at the interface of the composite photoelectrode and the electrolyte is improved, and the water oxidation rate of the interface of the composite photoelectrode and the electrolyte is accelerated; meanwhile, the shell formed by the metal organic complex can accelerate the activation of interface water molecules, so that the transfer rate of interface carriers is improved, the water decomposition activity of the bismuth vanadate-metal organic complex composite photoelectrode is improved, and the BiVO is obtained4The metal-organic complex composite photoelectrode has excellent photoelectrocatalysis water oxidation performance.
Furthermore, the metal organic complex with the amorphous structure can remarkably passivate the surface state of the surface of the bismuth vanadate core and reduce the surface recombination rate of bismuth vanadate carriers, so that the concentration of photo-generated holes at the interface of the composite photoelectrode and the electrolyte is improved, and the oxidation rate of the composite photoelectrode and the electrolyte interface is accelerated.
The test results of the embodiment show that the photocurrent density of the bismuth vanadate-metal organic complex composite photoelectrode is greatly improved compared with that of bismuth vanadate, the structural stability is high, the photoelectrochemical property is excellent, the chemical stability is high, and the water oxidation activity can be effectively improved.
Drawings
FIG. 1 is BiVO in example 14XRD patterns of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode;
FIG. 2 is an XRD pattern of the metal organic complex in example 1;
FIG. 3 is an XPS plot of Fe2p element from the bismuth vanadate-metal organic complex composite photoelectrode of example 1;
FIG. 4 shows BiVO in example 14XPS diagram of C1s element of photoelectrode and bismuth vanadate-metal organic complex composite photoelectrode;
FIG. 5 is BiVO in example 14An IR diagram of a photoelectrode and a bismuth vanadate-metal organic complex composite photoelectrode;
FIG. 6 is BiVO in example 14A surface carrier recombination rate constant diagram of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode under different electrode potentials;
FIG. 7 is BiVO in example 24SEM image of photoelectrode and bismuth vanadate-metal organic complex composite photoelectrode, and (A) in FIG. 7 is BiVO4The photoelectrode (B) is a bismuth vanadate-metal organic complex composite photoelectrode;
FIG. 8 shows BiVO in example 24A linear scanning voltammetry curve graph of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode under the condition of optical on-off;
FIG. 9 shows BiVO obtained in example 34A current-time curve chart of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode under the external bias of 0.4V (vs. Ag/AgCl);
FIG. 10 shows the composite photoelectrode and BiVO obtained in comparative examples 1 to 24Linear sweep voltammogram of photoelectrode.
Detailed Description
The invention provides a bismuth vanadate-metal organic complex composite photoelectrode, which comprises a substrate and BiVO loaded on the surface of the substrate4-a metal organic complex composite film, said BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles; the BiVO4The metal-organic complex particles comprise BiVO4A kernel and a BiVO coated4A shell formed by a metal organic complex of the inner core;
the metal organic complex is Fe2+-2, 5-dihydroxyterephthalic acid complex.
In the invention, the bismuth vanadate-metal organic complex composite photo-electrode comprises a substrate. In the present invention, the substrate preferably comprises FTO conductive glass. The thickness of the substrate is not particularly limited in the present invention, and the thickness of the substrate known to those skilled in the art may be used.
In the invention, the bismuth vanadate-metal organic complex composite photo-electrode comprises BiVO loaded on the surface of the substrate4-a metal organic complex composite film, said BiVO4The-metal organic complex composite film is prepared from BiVO4-metal organic complex particles. In the invention, the BiVO4The thickness of the metal-organic complex composite film is preferably 1 to 50 μm, more preferably 1 to 10 μm, and still more preferably 2 to 5 μm.
In the invention, the BiVO4The metal-organic complex particles comprise BiVO4A kernel and a BiVO coated4An outer shell formed by the metal organic complex of the inner core.
In the invention, the BiVO4The particle size of the core is preferably 100 to 200nm, and more preferably 120 to 180 nm.
In the present invention, the metal-organic complex is Fe2+-2, 5-dihydroxyterephthalic acid complex. In the present invention, the Fe2+The complex of 2, 5-dihydroxyterephthalic acid means a complex of ferrous ion and 2, 5-dihydroxyterephthalic acid. In the present invention, the thickness of the outer shell is preferably set3 to 100nm, more preferably 10 to 90 nm. In the present invention, the metal-organic complex is preferably an amorphous structure.
The invention also provides a preparation method of the bismuth vanadate-metal organic complex composite photoelectrode in the technical scheme, which comprises the following steps:
providing BiVO4Photoelectrode of said BiVO4The photoelectrode comprises a substrate and BiVO loaded on the surface of the substrate4Film of said BiVO4The film is made of BiVO4Particle formation;
mixing inorganic metal salt, organic ligand and solvent to obtain inorganic metal salt-ligand mixed solution; the inorganic metal salt comprises an inorganic ferrous salt; the organic ligand is 2, 5-dihydroxy terephthalic acid;
BiVO (bismuth oxide) is added4And immersing the photoelectrode in an inorganic metal salt-ligand mixed solution, and carrying out hydrothermal reaction to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
In the present invention, each reagent in the preparation method is a commercially available product well known to those skilled in the art, unless otherwise specified.
The invention provides BiVO4Photoelectrode of said BiVO4The photoelectrode comprises a substrate and BiVO loaded on the surface of the substrate4Film of said BiVO4The film is made of BiVO4And (4) forming particles.
In the present invention, the substrate preferably comprises FTO conductive glass. The thickness of the substrate is not particularly limited in the present invention, and the thickness of the substrate known to those skilled in the art may be used.
In the invention, the BiVO4The photoelectrode comprises BiVO loaded on the surface of the substrate4Film of said BiVO4The film is made of BiVO4And (4) forming particles. In the invention, the BiVO4The thickness of the film is preferably 500 to 1000nm, more preferably 550 to 950 nm. In the invention, the BiVO4The particle size of the particles is preferably 100 to 200nm, and more preferably 120 to 180 nm.
In the invention, the BiVO4Preparation method of photoelectrodePreferably, the method comprises the following steps:
mixing the potassium iodide aqueous solution with bismuth nitrate to obtain a potassium iodide-bismuth nitrate mixed solution;
mixing the potassium iodide-bismuth nitrate mixed solution with an ethanol solution of p-benzoquinone to obtain an electrolyte solution;
under the existence of the electrolyte solution, carrying out constant potential deposition by taking a substrate as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum mesh as a counter electrode to obtain a BiOI photoelectrode;
mixing vanadium acetylacetonate and dimethyl sulfoxide to obtain a vanadium acetylacetonate solution;
dropwise coating the acetylacetone vanadium solution on the surface of the BiOI electrode, and calcining to obtain the BiVO4And a photoelectrode.
The invention mixes potassium iodide water solution with bismuth nitrate to obtain potassium iodide-bismuth nitrate mixed solution.
In the invention, the concentration of the potassium iodide aqueous solution is preferably 0.45-0.55 mol/L, and more preferably 0.5 mol/L. In the present invention, the pH of the aqueous potassium iodide solution is preferably 1.7.
In the present invention, the agent for adjusting the pH of the aqueous potassium iodide solution is preferably concentrated nitric acid, the concentration of which is preferably 68 wt.%. In the invention, the concentration of the bismuth nitrate in the potassium iodide-bismuth nitrate mixed solution is preferably 0.05-0.07 mol/L, more preferably 0.055-0.065 mol/L, and most preferably 0.06 mol/L. In the present invention, the potassium iodide aqueous solution is preferably prepared from potassium iodide and ultrapure water.
In the present invention, the mixing of the potassium iodide aqueous solution and the bismuth nitrate is preferably ultrasonic; the ultrasound is not particularly limited in the present invention, and may be ultrasound known to those skilled in the art.
After the mixed solution of potassium iodide and bismuth nitrate is obtained, the mixed solution of potassium iodide and bismuth nitrate is mixed with the ethanol solution of p-benzoquinone to obtain the electrolyte solution.
In the present invention, the concentration of p-benzoquinone in the ethanol solution of p-benzoquinone is preferably 0.25 to 0.35mol/L, more preferably 0.28 to 0.32mol/L, and most preferably 0.3 mol/L.
In the present invention, the volume ratio of the potassium iodide-bismuth nitrate mixed solution to the p-benzoquinone solution is preferably 5: (1.8-2.2), more preferably 5: (1.9-2.1), most preferably 5: 2.
after the electrolyte solution is obtained, the method carries out constant potential deposition by taking the substrate as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum net as a counter electrode in the presence of the electrolyte solution to obtain the BiOI photoelectrode.
The Ag/AgCl electrode and the platinum net are not particularly limited in the invention, and the Ag/AgCl electrode and the platinum net which are well known to those skilled in the art can be adopted.
In the present invention, the potential of the potentiostatic deposition is preferably-0.05 to-0.2V, more preferably-0.08 to-1.5V, most preferably-0.1V; the time is preferably 3 to 10min, more preferably 4 to 8min, and most preferably 5 min.
After the constant potential deposition, the obtained sample is preferably cleaned to remove surface impurities; in the present invention, the cleaning agent preferably includes deionized water. The cleaning method of the present invention is not particularly limited, and a method known to those skilled in the art may be used.
The invention mixes vanadium acetylacetonate and dimethyl sulfoxide to obtain vanadium acetylacetonate solution.
In the invention, the concentration of the vanadium acetylacetonate solution is preferably 0.08-0.12 mol/L, and more preferably 0.1 mol/L.
After obtaining the vanadium acetylacetonate solution and the BiOI photoelectrode, the invention dropwise coats the vanadium acetylacetonate solution on the surface of the BiOI photoelectrode, and calcinates to obtain the BiVO4And a photoelectrode.
In the invention, the preferable dropping amount of the vanadium acetylacetonate solution on the surface of the BiOI electrode is 100-120 mu L/cm2More preferably 105 to 115. mu.L/cm2. In the invention, the calcination temperature is preferably 440-460 ℃, more preferably 445-455 ℃, and most preferably 450 ℃; the time is preferably 1.5 to 2.5 hours, more preferably 1.8 to 2.3 hours, and most preferably 2 hours. In the present invention, the calcination is preferably carried out in a muffle furnace. In thatIn the present invention, during the calcination process, BiOI is decomposed into Bi2O3Decomposition of vanadyl acetylacetonate to V2O5Said Bi2O3And V2O5High-temperature solid-phase reaction is carried out to generate BiVO4。
In the present invention, the calcination preferably further comprises washing, and specifically, the washing is preferably to soak the sample obtained by calcination in a sodium hydroxide solution to remove residual V2O5To obtain BiVO4And a photoelectrode. In the present invention, the concentration of the sodium hydroxide solution is preferably 1 mol/L. In the invention, the soaking temperature is preferably 18-25 ℃, and the soaking time is preferably 30 min.
The invention mixes inorganic metal salt, organic ligand and solvent to obtain inorganic metal salt-ligand mixed solution.
In the present invention, the inorganic metal salt includes an inorganic ferrous salt. In the present invention, the inorganic ferrous salt preferably includes ferrous chloride, ferrous sulfate, or ferrous nitrate. In the present invention, the organic ligand is 2, 5-dihydroxyterephthalic acid.
In the present invention, the molar ratio of the inorganic metal ion to the organic ligand in the inorganic metal salt-ligand mixed solution is preferably 1: (2-3), more preferably 1: (2.2-2.8).
In the present invention, the solvent is preferably ethanol, water and N, N-Dimethylformamide (DMF). In the present invention, the volume ratio of ethanol, water, and N, N-dimethylformamide in the solvent is preferably 1: 1: (10-20).
In the present invention, the concentration of the inorganic metal salt in the inorganic metal salt-ligand mixed solution is preferably 8 to 50mmol/L, and more preferably 8.2 to 30 mmol/L.
Obtaining BiVO4After photoelectrode and inorganic metal salt-ligand mixed solution, BiVO is mixed4And immersing the photoelectrode in an inorganic metal salt-ligand mixed solution, and carrying out hydrothermal reaction to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
In the invention, the temperature of the hydrothermal reaction is preferably 130-150 ℃, more preferably 135-145 ℃; the time is preferably 10 to 16 hours, and more preferably 11 to 15 hours. In the present invention, the hydrothermal reaction is preferably carried out in a stainless steel autoclave. In the invention, ferrous ions and 2, 5-dihydroxy terephthalic acid ligand are subjected to self-assembly reaction to generate a metal organic complex with an amorphous structure.
After the hydrothermal reaction, the present invention preferably further comprises: and sequentially cleaning and drying products obtained by the hydrothermal reaction to obtain the bismuth vanadate-metal organic complex composite photoelectrode. In the present invention, the washing preferably includes ethanol washing and water washing alternately. In the invention, the drying temperature is preferably 40-65 ℃, and more preferably 45-60 ℃; the time is preferably 5 to 30min, and more preferably 10 to 25 min. In the present invention, the drying apparatus is preferably an oven.
The invention also provides an application of the bismuth vanadate-metal organic complex composite photoelectrode in the technical scheme or the bismuth vanadate-metal organic complex composite photoelectrode obtained by the preparation method in the technical scheme as a catalytic electrode in photoelectrocatalysis water oxidation reaction.
The application of the invention is not particularly limited, and the application of the catalytic electrode in the photoelectrocatalysis water oxidation reaction which is well known to those skilled in the art can be adopted.
In order to further illustrate the present invention, the following will describe in detail a bismuth vanadate-metal organic complex composite photoelectrode, and a preparation method and application thereof, provided by the present invention, with reference to the following examples, which should not be construed as limiting the scope of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Mixing potassium iodide and ultrapure water, and adjusting the pH value to 1.7 by using concentrated nitric acid with the concentration of 68 wt% to obtain a potassium iodide aqueous solution with the concentration of 0.5 mol/L; mixing bismuth nitrate with the potassium iodide aqueous solution, and dissolving by ultrasonic to obtain a potassium iodide-bismuth nitrate mixed solution with the concentration of bismuth nitrate of 0.06 mol/L;
mixing p-benzoquinone with ethanol, and ultrasonically dissolving to obtain an ethanol solution of the p-benzoquinone with the concentration of 0.3 mol/L;
mixing the potassium iodide-bismuth nitrate mixed solution and an ethanol solution of p-benzoquinone in a ratio of 5: 2, and uniformly stirring to obtain an electrolyte solution; under the existence of the electrolyte solution, performing electrodeposition for 5min under the potential condition of-0.1V by using FTO conductive glass as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum mesh as a counter electrode, and cleaning by using deionized water to remove surface impurities after the deposition is finished to obtain a BiOI photoelectrode;
mixing vanadium acetylacetonate with dimethyl sulfoxide to obtain 0.1mol/L vanadium acetylacetonate solution, transferring 100 mu L vanadium acetylacetonate solution by using a liquid transfer gun, and coating the solution on the surface of the BiOI electrode (the dropping amount of the vanadium acetylacetonate solution on the surface of the BiOI electrode is 100 mu L/cm)2) Then placing the mixture in a muffle furnace, calcining for 2h at 450 ℃, naturally cooling to room temperature, taking out the obtained product, placing the product in 1mol/L sodium hydroxide solution, and soaking for 30min at room temperature (25 ℃) to remove residual V2O5To obtain BiVO4A photoelectrode;
mixing ferrous sulfate, ligand 2, 5-dihydroxyterephthalic acid and a solvent, wherein the solvent is a mixed solution of ethanol, water and N, N-dimethylformamide, and the volume ratio of the ethanol to the water to the N, N-dimethylformamide is 1: 1: 16, obtaining an inorganic ferrite-ligand mixed solution, wherein the concentration of the inorganic ferrite in the inorganic ferrite-ligand mixed solution is 10.42mmol/L, and the concentration of the ligand is 20.84 mmol/L;
the obtained BiVO4The photoelectrode is arranged in a stainless steel high-pressure reaction kettle, the conductive surface faces downwards and leans against the inner lining of the stainless steel high-pressure reaction kettle, and inorganic ferrous salt-ligand solution is added into the inner lining of the stainless steel high-pressure reaction kettle until the BiVO is immersed4A photoelectrode is subjected to hydrothermal reaction for 12 hours at 120 ℃, the hydrothermal reaction product is taken out after the reaction is finished, the product is respectively washed by ethanol and deionized water for 3 times and dried for 30min at 60 ℃, and the bismuth vanadate-metal organic complex is obtainedThe composite photoelectrode.
For BiVO in example 14X-ray diffraction tests are carried out on the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode, and the obtained XRD pattern is shown in figure 1. As can be seen from FIG. 1, the diffraction peaks at 28.9 °, 30.5 °, 34.5 °, 35.1 °, 40.2 ° and 42.4 ° correspond to monoclinic bismuth vanadate as known from crystal search software, and the PDF card number is 14-0688; the remaining diffraction peaks may correspond well to SnO2(ii) a In addition, no diffraction peak of other substances is found, which indicates that the prepared bismuth vanadate is pure phase; bismuth vanadate-metal organic complex composite photoelectrode diffraction peak position and simple BiVO4The diffraction peaks of other substances do not appear, and the loaded Fe-based metal organic complex is either amorphous or has lower loading amount
In order to further confirm the crystallinity of the supported metal-organic complex, the metal-organic complex in the hydrothermal reaction kettle was obtained by centrifugation, ethanol and water washing, and the crystallinity of the obtained metal-organic complex was measured by an X-ray diffractometer, and the XRD pattern obtained was shown in fig. 2. As can be seen from fig. 2, the XRD pattern of the metal-organic complex shows a very broad diffraction peak, indicating that the simple metal-organic complex has an amorphous structure.
BiVO in example 1 was tested by X-ray photoelectron spectroscopy4The photoelectrode and the obtained bismuth vanadate-metal organic complex composite photoelectrode have XPS graphs shown in figures 3 to 4, wherein figure 3 is the XPS graph of Fe2p element of the bismuth vanadate-metal organic complex composite photoelectrode in example 1, and figure 4 is BiVO in example 14XPS diagram of C1s element of photoelectrode and bismuth vanadate-metal organic complex composite photoelectrode. As can be seen from FIG. 3, two peaks appear at binding energies of 724eV and 711eV, which correspond to Fe2p 1/2 and Fe2p 3/2 signals, respectively, and can be deconvoluted well to Fe3+And Fe2+The existence of Fe element is confirmed; in addition, as can be seen from fig. 4, the C1s spectrum has two new characteristic peaks with binding energies of 288.8eV and 286.6eV, respectively, which are derived from the C ═ O and C — O groups of the ligand.
BiVO (BiVO) test by infrared spectrum4A photoelectrode and a bismuth vanadate-metal organic complex composite photoelectrode,the resulting IR pattern is shown in FIG. 5. As can be seen from FIG. 5, the wave numbers of the bismuth vanadate-metal organic complex composite photoelectrode are 1556, 1415, 1240, 1200, 1112, 1031, 560 and 514cm-1Generates a plurality of new peaks, wherein the peak is 1556cm-1The peak can be attributed to asymmetric stretching vibration of carboxyl group, 500-800cm-1The series of peaks in (B) is derived from the vibration of benzene ring, 1112cm-1The peak at (a) is derived from C-OH oscillations; in combination with all these characterizations, the presence of the metal organic complex can be well confirmed.
For BiVO4The photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode are tested for surface carrier recombination rate constants under different electrode potentials, and the test result is shown in figure 6. As can be seen from fig. 6, the surface carrier recombination rate constant of the bismuth vanadate-metal organic complex composite photoelectrode provided by the present invention is lower at different electrode potentials, which indicates that the bismuth vanadate-metal organic complex composite photoelectrode provided by the present invention can significantly improve the photo-generated hole concentration at the interface between the composite photoelectrode and the electrolyte, and is beneficial to accelerating the interface water oxidation rate.
Example 2
BiVO was prepared according to the method of example 14A photoelectrode;
mixing ferrous chloride, ligand 2, 5-dihydroxyterephthalic acid and a solvent, wherein the solvent is a mixed solution of ethanol, water and N, N-dimethylformamide, and the volume ratio of the ethanol to the water to the N, N-dimethylformamide is 1: 1: 20, obtaining an inorganic ferrite-ligand mixed solution, wherein the concentration of ferrous chloride in the inorganic ferrite-ligand mixed solution is 10.42mmol/L, and the concentration of the ligand is 22.22 mmol/L;
the obtained BiVO4The photoelectrode is arranged in a stainless steel high-pressure reaction kettle, the conductive surface faces downwards and leans against the inner lining of the stainless steel high-pressure reaction kettle, and inorganic ferrous salt-ligand solution is added into the inner lining of the stainless steel high-pressure reaction kettle until the BiVO is immersed4And carrying out a hydrothermal reaction for 8h at 120 ℃, taking out the obtained hydrothermal reaction product after the reaction is finished, washing the hydrothermal reaction product with ethanol and deionized water for 3 times respectively, and drying the hydrothermal reaction product for 30min at 60 ℃ to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
For BiVO in example 24Scanning electron microscopy testing is carried out on the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode, the obtained SEM image is shown in figure 7, and BiVO is shown in figure 7 (A)4The photoelectrode (B) is a bismuth vanadate-metal organic complex composite photoelectrode. BiVO is shown in FIG. 7 (A)4Is nano-particles, and the surface is smooth; as can be seen from FIG. 7 (B), the metal-organic complex is uniformly supported on BiVO4The surface of the particles forms a stable core-shell structure, which shows that the 2, 5-dihydroxyterephthalic acid can be used as a coupling agent to firmly adhere the metal organic complex to BiVO4Particle surface, wherein the BiVO4The particle size of the nano particles is 100-200 nm, and the thickness of the shell layer is 3-100 nm.
For BiVO4The photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode are subjected to linear scanning voltammetry tests under dark state and illumination conditions, and the obtained linear scanning voltammetry curve graph under the light on-off condition is shown in figure 8. As can be seen from FIG. 8, BiVO in the dark state4The current of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode is very low, which indicates that water decomposition cannot be realized in a dark state; after illumination, the current is obviously increased, and the current is increased along with the increase of the potential. However, in contrast, the bismuth vanadate-metal organic complex composite photoelectrode is less modified BiVO4The photocurrent of the photoelectrode is remarkably improved, for example, the current density of the bismuth vanadate-metal organic complex composite photoelectrode reaches 1.38mA cm under the bias of 0.4V (vs. Ag/AgCl)-2Is BiVO44.6 times of photoelectrode. The result shows that the bismuth vanadate-metal organic complex composite photoelectrode provided by the invention is BiVO after loading a metal organic complex4The interface charge transfer resistance of the photoelectrode is obviously reduced, so that the water oxidation reaction rate is obviously improved, and the water oxidation activity is further effectively improved.
Example 3
BiVO was prepared according to the method of example 14A photoelectrode;
mixing ferrous nitrate, ligand 2, 5-dihydroxyterephthalic acid and a solvent, wherein the solvent is a mixed solution of ethanol, water and N, N-dimethylformamide, and the volume ratio of the ethanol to the water to the N, N-dimethylformamide is 1: 1: 16, obtaining an inorganic ferrite-ligand mixed solution, wherein the concentration of the inorganic ferrite in the inorganic ferrite-ligand mixed solution is 8.33mmol/L, and the concentration of the ligand is 22.22 mmol/L;
the obtained BiVO4The photoelectrode is arranged in a stainless steel high-pressure reaction kettle, the conductive surface faces downwards and leans against the inner lining of the stainless steel high-pressure reaction kettle, and inorganic ferrous salt-ligand solution is added into the inner lining of the stainless steel high-pressure reaction kettle until the BiVO is immersed4And carrying out a hydrothermal reaction for 12h at 120 ℃, taking out the obtained hydrothermal reaction product after the reaction is finished, washing the hydrothermal reaction product with ethanol and deionized water for 3 times respectively, and drying the hydrothermal reaction product for 30min at 60 ℃ to obtain the bismuth vanadate-metal organic complex composite photoelectrode.
BiVO obtained in test example 34Testing the current-time relationship of the photoelectrode and the bismuth vanadate-metal organic complex composite photoelectrode under the external bias of 0.4V (vs. Ag/AgCl), and testing the KHCO of 0.1mol/L electrolyte solution3The solution, electrolyte solution, had a pH of 9 and the resulting current-time graph is shown in FIG. 9. As can be seen from FIG. 9, BiVO4The current density of the photoelectrode gradually decreases with time; after 3h, BiVO4The current density of the photoelectrode is increased from 0.26mA cm at the initial stage-2Reduced to 0.12mA cm-2Description of simple BiVO4The photoelectrode has poor stability. The current density of the bismuth vanadate-metal organic complex composite photoelectrode is higher than that of bismuth vanadate, the current density of the bismuth vanadate-metal organic complex composite photoelectrode is small in change along with time, and the current density is almost not attenuated after 3 hours, so that the stability and the activity of the bismuth vanadate electrode are effectively improved by uniform loading of the metal organic complex, and the bismuth vanadate-metal organic complex composite photoelectrode has great application potential in the field of photoelectrocatalysis water decomposition.
Comparative example 1
The concentration of ferrous chloride in the inorganic ferrous salt-ligand mixed solution is 44.44mol/L, the concentration of the ligand is 22.22mol/L, and the rest technical means are the same as those in the embodiment 2, so that the composite photoelectrode is obtained, wherein the metal organic complex in the composite photoelectrode is in a crystalline form.
Comparative example 2
The concentration of ferrous chloride in the inorganic ferrous salt-ligand mixed solution is 66.66mol/L, the concentration of the ligand is 22.22mol/L, and the other technical means are the same as those in the embodiment 2, so that the composite photoelectrode is obtained, wherein the metal organic complex in the composite photoelectrode is in a crystalline form.
The composite photoelectrode and BiVO obtained by contrast ratio 1-24The photoelectrode was subjected to a linear sweep voltammetry test, and the resulting linear sweep voltammetry graph is shown in fig. 10. As can be seen from fig. 10, the crystalline organometallic complex has an inhibitory effect on the water decomposition performance of bismuth vanadate; further analysis shows that in the invention, when the concentration of the organic ligand is increased, the metal organic complex with an amorphous structure is obtained, and the water decomposition performance of the bismuth vanadate-based bismuth vanadate-metal organic complex composite photoelectrode can be better improved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.