A bridge-type heterogeneous reaction cell with bandgap splitting and its application

Abstract

The present invention relates to the technical field of catalytic reaction cells, and in particular to a bridge-type heterogeneous reaction cell with bandgap splitting and its application. It includes two electrode chambers. The electrode materials in the two electrode chambers both contain semiconductor materials, and the two electrode materials have the property of bandgap splitting. One of them is a semiconductor material with a high oxidation potential, and the other is a semiconductor material with a high reduction potential. The two semiconductor materials with bandgap splitting are bridged through a photo-generated carrier conduction medium. The technical solution of the present invention uses the semiconductor materials with bandgap splitting as the electrode materials of the reaction cell, and the combination of the semiconductor materials with bandgap splitting is bridged, so that a wide spectral response range, a high oxidation-reduction potential, and a high photo-generated carrier separation efficiency can be obtained simultaneously. The preparation method of this reaction cell is simple, has great commercial application potential, and has good application prospects in photo / photoelectrocatalysis.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic reaction cells, and in particular to a bridge-type heterogeneous reaction cell with bandgap splitting and its application. Background Art

[0002] Photocatalytic / photoelectrocatalytic technology has the characteristics of mild reaction conditions, low energy consumption, environmental friendliness, etc., and is one of the most promising technologies for energy catalytic conversion and storage, pollutant degradation, and synthesis of organic value-added chemicals. The catalytic reaction cell is one of the cores of photocatalytic / photoelectrocatalytic technology. An efficient photocatalytic / photoelectrocatalytic reaction cell should enable the catalytic system to achieve a wide spectral response range, high redox potential, and high photogenerated carrier separation efficiency.

[0003] Compared with the half-reaction cell catalytic system containing only semiconductor photo / photoelectrodes, both the positive and negative electrodes of the photocatalytic / photoelectrochemical integrated reaction cell are composed of semiconductor materials, and its catalytic activity can be obtained by synergistically combining the properties of the two electrode semiconductors, which is superior to that of the component half-reaction cell (Adv. Mater. 2021, 33, 2005389.; ACS Catal. 2022, 12, 2415-2425). Currently, the most promising photocatalytic / photoelectrochemical integrated reaction cell is the Z-type reaction cell constructed by combining bandgap staggered semiconductors. For example, the integrated Z-type reaction cell constructed by coupling the anodic Co4O4 / pGO / BiVO4 / SnO x and the cathodic Pt / TiO x / PIP / CuO x (Co4O4 / pGO / BiVO4 / SnO x -CuO x / PIP / TiO x / Pt) realizes the complementary absorption of light by the two electrodes and the efficient separation of photogenerated charges, thereby achieving efficient photocatalytic hydrogen production under zero output bias, and its STH hydrogen production efficiency is as high as 4.3% (J. Am. Chem. Soc. 2021, 143, 32, 12499-12508). However, the inherent characteristic of the bandgap staggering of the semiconductors composing the Z-type reaction cell makes there a balance relationship between the redox potential and the wide spectral response of the reaction cell, and it is difficult to simultaneously obtain a high redox potential and a wide spectral response range through simple design, thus limiting the improvement space of its catalytic activity and commercial application potential. Therefore, there is an urgent need to develop a new type of integrated photocatalytic / photoelectrochemical reaction cell that can simultaneously achieve a wide spectral response range, redox potential, and photogenerated carrier separation efficiency under simple design. Summary of the Invention

[0004] The first object of the present invention is to provide a bridge-type heterogeneous reaction cell with bandgap splitting. The structure of the bridge-type heterogeneous reaction cell is simple, and it can simultaneously obtain a wide spectral response range, a high redox potential, and a high separation efficiency of photo-generated carriers. The present invention also provides the application of the bridge-type heterogeneous reaction cell with bandgap splitting in photo / photoelectrocatalysis.

[0005] A bridge-type heterogeneous reaction cell with bandgap splitting provided by the present invention includes two electrode chambers. The electrode materials in the two electrode chambers both contain semiconductor materials, and the two electrode materials have the property of bandgap splitting. One of them is a semiconductor material with a high oxidation potential, and the other is a semiconductor material with a high reduction potential. The photo-generated carriers of the two bandgap-split semiconductor materials can be effectively separated through a conduction medium bridge.

[0006] Preferably, the combination of the two electrodes is a sulfide semiconductor - oxide semiconductor or a carbon-based semiconductor - sulfide semiconductor.

[0007] Preferably, the combination of the two electrodes is one of: ZnIn2S4 - CuS, CuInS2 - MnO2, ZnFe2O4 - CuS, CuInS2 - WO 3-x or g-C3N4 - CuS.

[0008] Preferably, the conduction medium is a solution containing a redox ion pair.

[0009] Preferably, the redox ion pair is: I3 - / I - 、Fe 3+ / Fe 2+ 、VO2 + / VO 2+ 、[Co(bpy)3] 3+ / [Co(bpy)3] 2+ 、or NO3 - / NO2 - One of them.

[0010] The application of the above-mentioned bridge-type heterogeneous reaction cell with bandgap splitting provided by the present invention in photo / photoelectrocatalysis is used for photo / photoelectrocatalytic water splitting for hydrogen production, carbon dioxide reduction, organic pollutant degradation, or organic value-added chemical synthesis.

[0011] In summary, the present invention has the following advantages compared with the prior art:

[0012] (1) The technical solution of the present invention uses a semiconductor material with bandgap splitting as the electrode of the reaction cell, and two semiconductor materials with bandgap splitting are combined and bridged by a photo-generated carrier conduction medium, which overcomes the balance relationship between the redox potential and the broad-spectrum response caused by the inherent characteristic of bandgap staggering of the semiconductor combination in traditional bandgap staggered reaction cells, such as Z-type reaction cells. The bandgap-splitting bridge-type heterogeneous reaction cell can simultaneously obtain a broad-spectrum response range, a high redox potential, and a high photo-generated carrier separation efficiency.

[0013] (2) The preparation method of the bandgap-splitting bridge-type heterogeneous reaction cell provided by the present invention is simple. The electrode material can be directly constructed using a narrow-bandgap semiconductor with cheap and single synthetic raw materials, breaking through the thinking of using multiple semiconductors or co-catalysts to construct composite electrode materials in traditional reaction cells to obtain broad-spectrum absorption, and has great commercial application potential.

[0014] (3) The bandgap-splitting bridge-type heterogeneous reaction cell provided by the present invention has good application effects in photocatalysis / photoelectrocatalysis, has a high hydrogen production rate in catalytic hydrolysis for hydrogen production, a fast degradation rate of catalytic organic pollutants, a high carbon monoxide production rate in catalytic carbon dioxide reduction, and a high production rate of catalytic synthesis of organic value-added chemicals. Description of the Drawings

[0015] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a schematic diagram of the structure and principle of the bandgap-splitting bridge-type heterogeneous reaction cell in the embodiment of the present invention. Detailed Embodiments

[0017] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1

[0021] A bridge-type heterogeneous reaction cell with bandgap splitting includes two electrode chambers. The electrodes in the two electrode chambers are ZnIn2S4 electrode and CuS electrode respectively. The ZnIn2S4 electrode and CuS electrode have the property of bandgap splitting. They are bridged through a photo-generated carrier conduction medium to achieve a high carrier separation efficiency. The photo-generated carrier conduction medium is an aqueous solution containing I3 - / I - .

[0022] The preparation method of the above bridge-type heterogeneous reaction cell with bandgap splitting is as follows:

[0023] (1) Select two semiconductor materials with bandgap splitting: ZnIn2S4 and CuS. Among them, ZnIn2S4 is used as the semiconductor material with a high reduction potential, and CuS is used as the semiconductor material with a high oxidation potential.

[0024] (2) Place the two semiconductor materials on the conductive carriers respectively to prepare electrodes. Both conductive carriers use conductive glass.

[0025] The preparation process of the ZnIn2S4 electrode is as follows: First, dissolve 0.5 mmol of ZnCl2, 1 mmol of InCl3·4H2O and 3 mmol of thioacetamide in 60 mL of deionized water; then, add the above mixed solution to a 100 mL stainless steel autoclave equipped with a polytetrafluoroethylene liner, place it in a forced-air oven and react at 200 °C for 24 hours. After the product is centrifuged and separated, it is dried at 80 °C to obtain ZnIn2S4 powder material; finally, take 5 mg of ZnIn2S4 powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the conductive glass. After natural drying, the ZnIn2S4 electrode is obtained.

[0026] The preparation process of the CuS electrode is as follows: First, dissolve 1 mmol of Cu(NO3)2·3H2O and 2 mmol of thiourea in 60 mL of ethylene glycol; then, add the above mixed solution to a 100 mL stainless steel autoclave equipped with a polytetrafluoroethylene liner, place it in a forced-air oven and react at 180 °C for 12 hours. After centrifuging the product, dry it at 80 °C to obtain the CuS powder material; finally, take 5 mg of the CuS powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the conductive glass. After natural drying, the CuS electrode is obtained.

[0027] (3) Place the ZnIn2S4 electrode and the CuS electrode into an H-type electrolytic cell with a diaphragm. The ZnIn2S4 electrode serves as the cathode of the reaction cell and is connected to the negative electrode of the electrochemical workstation, while the CuS electrode serves as the anode of the reaction cell and is connected to the positive electrode of the electrochemical workstation.

[0028] (4) Finally, add an aqueous solution containing the I3 - / I - ion pair to the H-type electrolytic cell to obtain a bridge-type heterojunction reaction cell ZnIn2S4-I3 - / I - -CuS. The obtained ZnIn2S4-I3 - / I - -CuS reaction cell achieves full-spectrum absorption, and its oxidation potential and reduction potential are as high as 2.9 V and -1.3 V respectively. The photocurrent response intensity is significantly higher than that of its single electrodes ZnIn2S4 and CuS.

[0029] Example 2

[0030] A bridge-type heterojunction reaction cell with bandgap splitting includes two electrode chambers. The electrodes in the two electrode chambers are a CuInS2 electrode and a MnO2 electrode respectively. The CuInS2 electrode and the MnO2 electrode have the property of bandgap splitting, and they are bridged by a photo-generated carrier conduction medium to achieve a high carrier separation efficiency. The photo-generated carrier conduction medium is an aqueous solution containing Fe 3+ / Fe 2+ aqueous solution.

[0031] The preparation method of the above bridge-type heterojunction reaction cell with bandgap splitting is as follows:

[0032] (1) Select two semiconductor materials with bandgap splitting: CuInS2 and MnO2, where CuInS2 is used as the semiconductor material with a high reduction potential and MnO2 is used as the semiconductor material with a high oxidation potential.

[0033] (2) Place the two semiconductor materials on conductive carriers respectively to prepare electrodes. One of the conductive carriers uses carbon cloth, and the other conductive carrier uses conductive glass.

[0034] The preparation process of the CuInS2 electrode is as follows: First, 0.05 mmol of CuCl2·2H2O, 0.05 mmol of InCl3·4H2O and 0.2 mmol of thiourea are dissolved in 60 mL of ethylene glycol and then transferred into a 100 mL stainless steel autoclave equipped with a polytetrafluoroethylene liner; Then, react at 200 °C for 10 hours in a forced air oven, and after centrifugal separation of the product, dry it at 80 °C to obtain CuInS2 powder material; Finally, take 5 mg of CuInS2 powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the conductive carbon cloth. After natural air drying, the CuInS2 electrode is obtained.

[0035] The preparation process of the MnO2 electrode is as follows: First, prepare a mixed aqueous solution of 0.1 mol / L Mn(CH3COO)2 and 0.01 mol / L Na2SO4 as the precursor solution; Immerse a 1 cm -2 piece of conductive glass (FTO) into the electrolyte solution and deposit it under a constant current of 1 mA cm -2 ; Finally, place the electro-deposited sample in a muffle furnace and calcine it at 400 °C for 2 hours to obtain the MnO2 electrode.

[0036] (3) Place the CuInS2 electrode and the MnO2 electrode into an H-type electrolytic cell with a diaphragm. The CuInS2 electrode serves as the cathode of the reaction cell and is connected to the negative electrode of the electrochemical workstation, while the MnO2 electrode serves as the anode of the reaction cell and is connected to the positive electrode of the electrochemical workstation.

[0037] (4) Finally, add an aqueous solution containing Fe 3+ / Fe 2+ ion pairs into the H-type electrolytic cell to obtain a bridge-type heterogeneous reaction cell CuInS2-Fe 3+ / Fe 2+ -MnO2 with split bandgap. The obtained CuInS2-Fe 3+ / Fe 2+ -MnO2 reaction cell achieves full-spectrum absorption, and its oxidation potential and reduction potential are as high as 2.0 V and -1.0 V respectively, and the photocurrent response intensity is significantly higher than that of its single electrodes CuInS2 and MnO2.

[0038] Example 3

[0039] A bridge-type heterogeneous reaction cell with split bandgap, comprising two electrode chambers. The electrodes in the two electrode chambers are ZnFe2O4 electrode and CuS electrode respectively. The ZnFe2O4 electrode and the CuS electrode have the characteristic of split bandgap, and they are bridged by a photogenerated carrier conduction medium to achieve high carrier separation efficiency. The photogenerated carrier conduction medium is a medium containing VO2 + / VO 2+ aqueous solution

[0040] The preparation method of the above-mentioned band-gap splitting bridge-type heterogeneous reaction cell is as follows:

[0041] (1) Select two semiconductor materials with band-gap splitting: ZnFe2O4 and CuS, where ZnFe2O4 is used as the semiconductor material with high reduction potential and CuS is used as the semiconductor material with high oxidation potential.

[0042] (2) Place the two semiconductor materials on conductive carriers to prepare electrodes respectively. One conductive carrier uses conductive glass and the other conductive carrier uses copper sheet.

[0043] The preparation process of the ZnFe2O4 electrode is as follows: First, dissolve 0.2 mol / L FeSO4·7H2O and 0.1 mol / L Zn(NO3)2·6H2O in 50 mL of distilled water; then, use conductive glass as the cathode and a platinum sheet electrode as the anode, and electro-deposit for 180 seconds at a constant current density of 1 mA / cm -2 to obtain a ZnFe2O4 thin film growing on the surface of the conductive glass; finally, place the obtained material in a muffle furnace and calcine at 400 °C for 2 hours to obtain the ZnFe2O4 electrode.

[0044] The preparation process of the CuS electrode is as follows: Dissolve 1 mmol of Cu(NO3)2·3H2O and 2 mmol of thiourea in 60 mL of ethylene glycol. Add the above mixed solution to a 100 mL stainless steel autoclave equipped with a polytetrafluoroethylene inner lining, and then react at 180 °C in a forced-draft oven for 12 hours. After centrifuging the product, dry it at 80 °C to obtain a CuS powder material. Take 5 mg of the CuS powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the copper sheet. After natural drying, obtain the CuS electrode.

[0045] (3) Place the ZnFe2O4 electrode and the CuS electrode in an H-type electrolytic cell with a diaphragm. The ZnFe2O4 electrode is used as the cathode of the reaction cell and is connected to the negative electrode of the electrochemical workstation, and the CuS electrode is used as the anode of the reaction cell and is connected to the positive electrode of the electrochemical workstation.

[0046] (4) Finally, add an aqueous solution containing the VO2 + / VO 2+ ion pair to the H-type electrolytic cell to obtain a band-gap splitting bridge-type heterogeneous reaction cell ZnFe2O4-VO2 + / VO 2+ -CuS. The obtained ZnFe2O4-VO2 + / VO 2+The -CuS reaction cell achieves full-spectrum absorption, with its oxidation potential and reduction potential reaching as high as 2.9 V and -1.6 V respectively, and the photocurrent response intensity is significantly higher than that of its single electrodes ZnFe2O4 and CuS.

[0047] Example 4

[0048] A bridged heterojunction reaction cell with bandgap splitting includes two electrode chambers, and the electrodes in the two electrode chambers are CuInS2 electrode and WO 3-x electrode respectively. The CuInS2 electrode and WO 3-x electrode have the property of bandgap splitting, and they are bridged by a photo-generated carrier conduction medium to achieve a high carrier separation efficiency. The photo-generated carrier conduction medium is an aqueous solution containing [Co(bpy)3] 3+ / [Co(bpy)3] 2+ respectively.

[0049] The preparation method of the above-mentioned bridged heterojunction reaction cell with bandgap splitting is as follows:

[0050] (1) Select two semiconductor materials with bandgap splitting: CuInS2 and WO 3-x , where CuInS2 is used as the semiconductor material with a high reduction potential, and WO 3-x is used as the semiconductor material with a high oxidation potential.

[0051] (2) Place the two semiconductor materials on conductive carriers respectively to prepare electrodes. One conductive carrier uses a copper sheet, and the other conductive carrier uses a carbon cloth.

[0052] The preparation process of the CuInS2 electrode is as follows: First, dissolve 0.05 mmol of CuCl2·2H2O, 0.05 mmol of InCl3·4H2O and 0.2 mmol of thiourea in 60 mL of ethylene glycol, and then transfer it to a 100 mL stainless steel autoclave equipped with a PTFE liner; then react at 200 °C for 10 hours in a blast drying oven. After centrifuging the product, dry it at 80 °C to obtain the CuInS2 powder material; finally, take 5 mg of CuInS2 powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the copper sheet. After natural drying, the CuInS2 electrode is obtained.

[0053] WO 3-x The preparation process of the electrode is as follows: First, completely dissolve 1.7 g of WCl6 in 60 mL of absolute ethanol and pour it into a 100 mL stainless steel autoclave equipped with a PTFE liner; then react at 200 °C for 6 hours in a blast drying oven. After centrifuging the product, dry it at 80 °C to obtain the WO 3-x powder material; finally, take 5 mg of WO 3-xThe powder was ultrasonically dispersed in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and evenly dropped on the surface of the carbon cloth. After natural drying, WO 3-x electrode was obtained.

[0054] (3) The CuInS2 electrode and the WO 3-x electrode were placed in an H-shaped electrolytic cell with a diaphragm. The CuInS2 electrode was used as the cathode of the reaction cell and connected to the negative electrode of the electrochemical workstation, and the WO 3-x electrode was used as the anode of the reaction cell and connected to the positive electrode of the electrochemical workstation.

[0055] (4) Finally, an aqueous solution containing the [Co(bpy)3] 3+ / [Co(bpy)3] 2+ ion pair was added to the H-shaped electrolytic cell to obtain a bridge-type heterogeneous reaction cell CuInS2-[Co(bpy)3] 3+ / [Co(bpy)3] 2+ -WO 3-x . The obtained CuInS2-[Co(bpy)3] 3+ / [Co(bpy)3] 2+ -WO 3-x reaction cell achieved full-spectrum absorption, with its oxidation potential and reduction potential reaching as high as 2.8 V and -1.0 V respectively, and the photocurrent response intensity was significantly higher than that of its single electrodes CuInS2 and WO 3-x .

[0056] Example 5

[0057] A bridge-type heterogeneous reaction cell with bandgap splitting includes two electrode chambers. The electrodes in the two electrode chambers are g-C3N4 electrode and CuS electrode respectively. The g-C3N4 electrode and the CuS electrode have the property of bandgap splitting, and they are bridged by a photo-generated carrier conduction medium to achieve a high carrier separation efficiency. The photo-generated carrier conduction medium is an aqueous solution containing NO3 - / NO2 - .

[0058] The preparation method of the above bridge-type heterogeneous reaction cell with bandgap splitting is as follows:

[0059] (1) Select two semiconductor materials with bandgap splitting: g-C3N4 and CuS, where g-C3N4 is used as the semiconductor material with a high reduction potential and CuS is used as the semiconductor material with a high oxidation potential.

[0060] (2) The two semiconductor materials are respectively placed on conductive carriers to prepare electrodes, and both conductive carriers use conductive glass.

[0061] The preparation process of the g-C3N4 electrode is as follows: First, place the crucible containing 5 mmol of urea (CH4N2O) in a muffle furnace and calcine it at 500 °C for 2 hours in an air atmosphere to obtain g-C3N4 powder; then, take 5 mg of the g-C3N4 powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and evenly drop it on the surface of the conductive glass. After natural drying, the g-C3N4 electrode is obtained.

[0062] The preparation process of the CuS electrode is as follows: First, dissolve 1 mmol of Cu(NO3)2·3H2O and 2 mmol of thiourea in 60 mL of ethylene glycol; then, add the above mixed solution to a 100 mL stainless steel autoclave equipped with a polytetrafluoroethylene liner and react it at 180 °C for 12 hours in a forced-air oven. After centrifuging the product, dry it at 80 °C to obtain CuS powder; finally, take 5 mg of the CuS powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and evenly drop it on the surface of the conductive glass. After natural drying, the CuS electrode is obtained.

[0063] (3) Place the g-C3N4 electrode and the CuS electrode in an H-type electrolytic cell with a diaphragm. The g-C3N4 electrode serves as the cathode of the reaction cell and is connected to the negative electrode of the electrochemical workstation, while the CuS electrode serves as the anode of the reaction cell and is connected to the positive electrode of the electrochemical workstation.

[0064] (4) Finally, add an aqueous solution containing the NO3 - / NO2 ion pair to the H-type electrolytic cell to obtain a g-C3N4-NO3 - / NO2 - -CuS bridge-type heterogeneous reaction cell with bandgap splitting. The obtained g-C3N4-NO3 - / NO2 - -CuS reaction cell exhibits full-spectrum absorption, with oxidation and reduction potentials as high as 2.9 V and -1.2 V respectively, and the photocurrent response intensity is significantly higher than that of its single electrodes g-C3N4 and CuS.

[0065] Comparative Example 1

[0066] A half-reaction cell includes two electrode chambers. The electrodes in the two electrode chambers are a ZnIn2S4 electrode and a pure conductive glass electrode respectively. The conduction medium of the photogenerated carriers in the reaction cell is an aqueous solution containing I3 - / I - .

[0067] The preparation method of the above half-reaction cell is as follows:

[0068] (1) Select a semiconductor material and a pure conductive carrier as electrodes: ZnIn2S4 and pure conductive glass, where ZnIn2S4 serves as a reducing semiconductor material and the pure conductive glass serves as the conductive electrode material.

[0069] (2) Place the ZnIn2S4 material on the conductive carrier to obtain one of the electrodes, and use the pure conductive glass directly as the other electrode.

[0070] The preparation method of the ZnIn2S4 electrode is as follows: First, dissolve 0.5 mmol of ZnCl2, 1 mmol of InCl3·4H2O, and 3 mmol of thioacetamide in 60 mL of deionized water; then, add the above mixed solution to a 100 mL stainless steel autoclave equipped with a Teflon liner, place it in a forced-air oven, react at 200 °C for 24 hours, and after centrifuging the product, dry it at 80 °C to obtain the ZnIn2S4 powder material; finally, take 5 mg of the ZnIn2S4 powder and ultrasonically disperse it in a mixed solution of 0.5 mL of ethanol and 10 μL of 5% Nafion, and then evenly drop it on the surface of the conductive glass. After natural drying, the ZnIn2S4 electrode is obtained.

[0071] (3) Place the ZnIn2S4 electrode and the pure conductive glass electrode in an H-type electrolytic cell with a diaphragm. The ZnIn2S4 electrode serves as the cathode of the reaction cell and is connected to the negative electrode of the electrochemical workstation, and the pure conductive glass electrode serves as the anode of the reaction cell and is connected to the positive electrode of the electrochemical workstation.

[0072] (4) Finally, add an aqueous solution containing the I3 - / I - ion pair to the H-type electrolytic cell to obtain the half-reaction cell ZnIn2S4-I3 - / I - -g-pure conductive glass. The obtained ZnIn2S4-I3 - / I - -pure conductive glass half-reaction cell can only obtain light absorption in the range of 200 - 550 nm, and the reduction potential of the half-cell composed of a single ZnIn2S4 semiconductor is only -1.3 V.

[0073] Catalytic activity evaluation

[0074] Evaluate the catalytic activity of the band-gap splitting bridge-type heterogeneous reaction cell prepared in Examples 1 - 5 and the half-reaction cell prepared in Comparative Example 1 in photocatalytic / photoelectrocatalytic processes.

[0075] I. Evaluation of the reaction activity of photocatalytic / photoelectrocatalytic water splitting for hydrogen production coupled with the degradation of organic pollutants: Before the test, add methylene blue pollutants to the anode side of the reaction cells in Examples 1 - 5 and Comparative Example 1 to make their concentration reach 10 mg / L. Bubble the reaction cells with Ar gas for 15 min to remove O2. Then, under 150 mW cm-2 The Xe light source of the couples with the electrochemical workstation for a specific external bias reaction for a specific time. The reference electrode of the electrochemical workstation is an Ag / AgCl electrode. The amount of H2 produced at the cathode of the reaction cell is measured by a gas chromatograph, and the degradation rate of methylene blue pollutants at the anode is measured by an ultraviolet-visible spectrophotometer. The measurement results are shown in Table 1.

[0076] Table 1 Activity evaluation results of water splitting for hydrogen production coupled with organic pollutant degradation

[0077]

[0078] As can be seen from Table 1, the photo / photoelectrocatalytic water splitting hydrogen production rate and the degradation performance of methylene blue pollutants in the reaction cells of Examples 1-5 are significantly higher than those of Comparative Example 1. This is mainly because the overall redox potential and light absorption range of the bridge-type heterojunction reaction cell (Examples 1-5) constructed with semiconductor materials with staggered bandgaps are significantly larger than those of the half-reaction cell system constructed with a single semiconductor electrode.

[0079] II. Activity evaluation of photo / photoelectrocatalytic carbon dioxide reduction coupled with organic value-added product synthesis reaction: Before the test, the cathode sides of the reaction cells of Examples 1-5 and Comparative Example 1 were bubbled with CO2 gas for 30 minutes to remove O2 while achieving CO2 dissolution saturation. Then benzyl alcohol was added to the anode side of the reaction cell to make its concentration reach 0.02 mol / L. The reaction cell was connected to the electrochemical workstation and coupled with a -2 Xe light source with a specific external bias for a reaction of 2 hours. The reference electrode of the electrochemical workstation is an Ag / AgCl electrode. The yield of CO, the product of the CO2 reduction reaction at the cathode of the reaction cell, is measured by a gas chromatograph, and the yield of benzaldehyde, the organic value-added product synthesized by the oxidation of benzyl alcohol at the anode, is measured by liquid chromatography. The measurement results are shown in Table 2.

[0080] Table 2 Activity evaluation results of carbon dioxide reduction coupled with organic value-added product synthesis

[0081]

[0082] As can be seen from Table 2, the photo / photoelectrocatalytic CO2 reduction to CO rate and the benzyl alcohol oxidation to benzaldehyde yield in the reaction cells of Examples 1-5 are significantly higher than those of Comparative Example 1. This is mainly because the overall redox potential and light absorption range of the bridge-type heterojunction reaction cell (Examples 1-5) constructed with semiconductor materials with staggered bandgaps are significantly larger than those of the half-reaction cell system constructed with a single semiconductor electrode.

[0083] The combination of the two electrodes in the reaction cell of the present invention is not limited to the electrode combinations in the above-mentioned Embodiments 1-5, and can also be other combinations of sulfide semiconductors - oxide semiconductors or carbon-based semiconductors - sulfide semiconductors, or other semiconductor combinations with bandgap splitting characteristics, such as combinations of any two of nitrides, phosphides, and organic semiconductors, etc.

[0084] The conduction medium in the reaction cell of the present invention is not limited to the conduction media in the above-mentioned Embodiments 1-5, and can also be other solutions or conductors containing redox ion pairs.

[0085] The most prominent feature of the bridge-type heterojunction reaction cell with bandgap splitting provided by the present invention is that the component semiconductors have bandgap splitting. Its structure and principle are as Figure 1 shown, which is different from the bandgap staggered characteristics of the component semiconductors in all current reaction cells, such as the best Z-scheme reaction cell (Adv. Mater. 2017, 29, 1601694). The inherent bandgap staggered characteristic of the Z-type reaction cell composed of semiconductors results in a trade-off relationship between the redox potential and the broad-spectrum response of the reaction cell, that is, to increase the redox potential of the reaction cell, the bandgap of the semiconductor needs to be widened, but widening the bandgap will narrow its light absorption range. Therefore, it is difficult for the Z-type reaction cell with bandgap staggering to simultaneously obtain a high redox potential and a broad-spectrum response range through simple design. For the bridge-type heterojunction reaction cell with bandgap splitting of the present invention, since the bandgaps of the electrode semiconductor material combinations do not need to be kept staggered, the conduction band or valence band of the semiconductor can be shifted upward simultaneously and its bandgap can be narrowed, so a high redox potential and a broad-spectrum response range can be obtained through simple design.

[0086] The bridge-type heterojunction reaction cell with bandgap splitting provided by the present invention overcomes the technical bottleneck of the reaction cells with bandgap staggering, and can simultaneously obtain a broad-spectrum response range, a high redox potential, and a high photogenerated carrier separation efficiency; and it has excellent performance in photocatalytic / photoelectrocatalytic water splitting for hydrogen production, carbon dioxide reduction, organic pollutant degradation, or organic value-added product synthesis; the technical solution provided by the present invention is expected to break through the performance bottleneck of traditional reaction cells with bandgap staggering (such as Z-type reaction cells) and achieve commercial applications.

[0087] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bridge-type heterogeneous reaction cell with bandgap splitting, characterized in that, It includes two electrode chambers. The electrode materials in both electrode chambers contain semiconductor materials, and the two electrode materials have the property of bandgap splitting. One is a semiconductor material with a high oxidation potential, and the other is a semiconductor material with a high reduction potential. The photo-generated carriers of the two semiconductor materials with bandgap splitting can be effectively separated through a conduction medium bridge; The combination of the two electrodes is one of: ZnIn2S4-CuS, CuInS2-MnO2, ZnFe2O4-CuS, CuInS2-WO 3-x or g-C3N4-CuS; The conduction medium is a solution containing redox ion pairs; The redox ion pair is: I3 - / I - 、Fe 3+ / Fe 2+ 、VO2 + / VO 2+ 、[Co(bpy)3] 3+ / [Co(bpy)3] 2+ or NO3 - / NO2 - and one of them.

2. Application of the bridge-type heterogeneous reaction cell with bandgap splitting described in claim 1 in photo / photoelectrocatalysis, characterized in that, It is used for photocatalytic / photoelectrocatalytic water splitting for hydrogen production, carbon dioxide reduction, organic pollutant degradation, or synthesis of organic value-added chemicals.

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