Photocathode material and method for preparing same, photocathode and use thereof, and method for preparing ethylene glycol

Abstract

The application relates to the field of ethylene glycol, and discloses a photo-cathode material and a preparation method thereof, a photo-cathode and application thereof, and a preparation method of ethylene glycol. The photo-cathode material comprises polydopamine, amorphous carbon and CdIn2S4; and the weight ratio of the polydopamine, the amorphous carbon and the CdIn2S4 is 1:(2-5):(5-30). The photo-cathode material provided by the application comprises polydopamine, amorphous carbon and CdIn2S4, so that the photo-cathode material has good light absorption performance and carbon dioxide reduction capacity, and has high selectivity to ethylene glycol. The preparation method of the photo-cathode material provided by the application simplifies operation conditions and a process flow, and is convenient for industrialized production. The photo-cathode material provided by the application is used for preparing ethylene glycol, and has high selectivity and product quantity.

Description

Technical Field

[0001] The present invention relates to the field of ethylene glycol, and in particular to a photocathode material and a preparation method thereof, a photocathode and an application thereof, and a preparation method of ethylene glycol. Background Art

[0002] With the rapid development of industrialization and modernization, the emission of carbon dioxide (CO2) has increased year by year. As the main component of greenhouse gases, CO2 has caused global warming and the frequent occurrence of extreme weather, which has seriously affected people's lives. Solar energy, as a widely distributed, abundant, environmentally friendly, green and sustainable energy source, has attracted attention from countries around the world. Using solar energy as a driving force to convert CO2 and water into organic matter is a green chemical technology that people have long dreamed of. It is an essential technology to achieve the grand goal of carbon neutrality. At present, research on the catalytic reduction of carbon dioxide in water is mainly based on electrocatalysis, photocatalysis and photoelectric combined catalysis methods. The reduction products are mainly formic acid, carbon monoxide, methane, and other small molecular organic compounds. Most of the products reported so far have poor selectivity and low yield, and there are still certain difficulties in their application in actual industrial production.

[0003] CN106757136A discloses a method for preparing methanol from carbon dioxide and water. This method can directly obtain methanol from water and carbon dioxide under light conditions with high selectivity. However, it is limited by the FTO glass electrode and has limited application prospects.

[0004] CN105332002A discloses a method for preparing ethanol from carbon dioxide and water. This method can directly obtain ethanol from water and carbon dioxide under light conditions, with high selectivity. However, it is limited by the FTO glass electrode and has limited application prospects.

[0005] CN109234758A discloses a method for preparing long carbon chain oxygen-containing compounds using carbon dioxide and water. The method can prepare long carbon chain oxygen-containing compounds with a carbon content of about C 50 -C 300 The cracking process is used to prepare a series of downstream products, which are converted into various required high-value-added chemicals such as alkanes, olefins, gasoline and diesel. This is of great significance, but the reported product structures are unclear.

[0006] Ethylene glycol has a wide range of uses, primarily as a raw material for polyester and in antifreeze. Its synthesis methods primarily involve ethylene hydration and ethylene oxide hydration. Ethylene hydration requires high temperatures and pressures, resulting in significant energy consumption. Ethylene oxide is produced by oxidizing ethylene in air at 120°C over a silver catalyst, resulting in high costs.

[0007] Therefore, there is an urgent need to develop new photocathode materials for use in the preparation of ethylene glycol. Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of the prior art in preparing ethylene glycol, such as complexity, high energy consumption, poor selectivity and low yield, and to provide a photocathode material and a preparation method thereof, a photocathode and its application, and a method for preparing ethylene glycol.

[0009] In order to achieve the above object, the first aspect of the present invention provides a photocathode material, characterized in that the photocathode material comprises polydopamine, amorphous carbon and CdIn2S4;

[0010] The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

[0011] A second aspect of the present invention provides a method for preparing a photocathode material, wherein the method comprises the following steps:

[0012] 1) dispersing silica nanospheres and dopamine in a buffer solution for a first reaction to obtain polydopamine / silica nanospheres;

[0013] 2) annealing the polydopamine / silica nanospheres under a protective atmosphere to obtain a sample N / C-SiO2-T;

[0014] 3) The N / C-SiO2-T was evenly dispersed in ethylene glycol, and InCl3, CdCl2·2H2O, and L-cysteine ​​were added sequentially under stirring to carry out a second reaction to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T;

[0015] 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres are subjected to a third reaction with an HF aqueous solution to obtain hollow nanospheres CdIn2S4-N / C-2-T.

[0016] A third aspect of the present invention provides a photocathode, wherein the photocathode comprises the photocathode material according to claim 1 or a photocathode material prepared by the preparation method according to any one of claims 2 to 6.

[0017] A fourth aspect of the present invention provides use of the above-mentioned photocathode in the preparation of ethylene glycol.

[0018] A fifth aspect of the present invention provides a method for preparing ethylene glycol, wherein the method comprises:

[0019] Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode according to claim 7.

[0020] Through the above technical solution, the photocathode and its preparation method and application and the preparation method of ethylene glycol provided by the present invention achieve the following beneficial effects:

[0021] (1) The photocathode material provided by the present invention includes polydopamine, amorphous carbon and CdIn2S4, so that the photocathode material has excellent light absorption performance and catalytic carbon dioxide reduction ability, and has high selectivity for ethylene glycol;

[0022] (2) The preparation method of the photocathode material provided by the present invention simplifies the operating conditions and process flow, facilitating industrial production;

[0023] (3) The photocathode material provided by the present invention is used to prepare ethylene glycol, with high selectivity (ethylene glycol selectivity is 48-60%) and product amount (total amount of ethylene glycol is 102-167 mg). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a TEM image of the photocathode material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0026] A first aspect of the present invention provides a photocathode material, characterized in that the photocathode material comprises polydopamine, amorphous carbon and CdIn2S4;

[0027] The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

[0028] In the present invention, the photocathode material has excellent light absorption performance and catalytic carbon dioxide reduction ability, and has high selectivity for ethylene glycol.

[0029] In the present invention, when the weight ratio of polydopamine, amorphous carbon and CdIn2S4 does not meet the above range, the stability of the photocathode material is poor, resulting in poor product selectivity.

[0030] Furthermore, the weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(3-4):(15-20).

[0031] A second aspect of the present invention provides a method for preparing a photocathode material, wherein the method comprises the following steps:

[0032] 1) dispersing silica nanospheres and dopamine into a buffer solution to perform a first reaction, to obtain polydopamine / silica nanospheres;

[0033] 2) annealing the polydopamine / silica nanospheres in a protective atmosphere, to obtain sample N / C-SiO2-T;

[0034] 3) uniformly dispersing the N / C-SiO2-T in ethylene glycol, and adding InCl3, CdCl2·2H2O and L-cysteine in sequence under stirring, to perform a second reaction, to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T;

[0035] 4) performing a third reaction of the solid nanospheres CdIn2S4-N / C-SiO2-2-T with an aqueous HF solution, to obtain hollow nanospheres CdIn2S4-N / C-2-T.

[0036] According to the present application, in step 1), the mass-volume ratio of the silica nanospheres, dopamine and buffer solution is 1g:(0.4-3)g:(150-600)mL.

[0037] According to the present application, in step 1), the average diameter of the silica nanospheres is 50-300nm.

[0038] According to the present application, in step 1), the process of the first reaction comprises stirring, centrifugation, washing and drying.

[0039] According to the present application, the stirring condition comprises a time of 1-2h.

[0040] According to the present application, the drying condition comprises a temperature of 60-90℃ and a time of 12-36h.

[0041] According to the present application, in step 2), the annealing condition comprises a temperature of 600-900℃ and a time of 2-4h.

[0042] According to the present application, in step 2), the protective atmosphere is selected from argon and / or nitrogen.

[0043] According to the present application, in step 3), the mass-volume ratio of the N / C-SiO2-T and ethylene glycol is 1g:(300-1000)mL.

[0044] According to the present application, in step 3), the mass ratio of the InCl3, CdCl2·2H2O and L-cysteine is 1:(0.5-1):(0.5-2).

[0045] According to the present invention, in step 3), the process of the second reaction includes: reflux, centrifugation, washing and drying.

[0046] According to the present invention, the reflux conditions include: temperature of 150-200° C. and time of 0.5-3 h.

[0047] According to the present invention, the drying conditions include: temperature of 60-90° C. and time of 10-36 hours.

[0048] According to the present invention, in step 4), the mass volume ratio of the CdIn2S4-N / C-SiO2-2-T and the HF aqueous solution is 1 g:(100-500) mL.

[0049] According to the present invention, in step 4), the concentration of the HF aqueous solution is 1-7 wt%.

[0050] According to the present invention, in step 4), the process of the third reaction includes: etching, centrifugation, washing and drying.

[0051] According to the present invention, the etching conditions include: time is 12-48 hours; the drying conditions include: temperature is 60-90° C., time is 12-36 hours.

[0052] A third aspect of the present invention provides a photocathode, wherein the photocathode comprises the photocathode material according to claim 1 or a photocathode material prepared by the preparation method according to any one of claims 2 to 6.

[0053] In the present invention, the preparation method of the photocathode is to disperse the hollow nanospheres CdIn2S4-N / C-2-T in 0.5 mL of 0.5% Nafion ethanol solution, and then dropwise add the solution to a 1×2 cm 2 The photocathode was obtained by placing the film on carbon paper and drying it in a vacuum drying oven at 80 °C for 8 h.

[0054] A fourth aspect of the present invention provides use of the above-mentioned photocathode in the preparation of ethylene glycol.

[0055] A fifth aspect of the present invention provides a method for preparing ethylene glycol, wherein the method comprises:

[0056] Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode according to claim 7.

[0057] According to the present invention, the electrolytic cell further comprises a photoanode, and the photoanode is selected from any one of BiVO4 / Ni, BiVO4 / Cu, BiVO4 / Al and BiVO4 / Ti;

[0058] According to the present invention, the electrolytic cell further comprises an electrolyte, the electrode liquid is an inorganic salt solution, and the inorganic salt solution is selected from an aqueous solution of KHCO3 and / or NaHCO3;

[0059] According to the present invention, the concentration of the inorganic salt solution is 0.05-0.2 mol / L;

[0060] According to the present invention, the voltage between the photocathode and the photoanode is 0.6-1.3V;

[0061] According to the present invention, the electrolyte of the photoanode further comprises an organic dye;

[0062] According to the present invention, the organic dye is at least one selected from the group consisting of eosin Y, methylene blue, Nile red and methyl violet.

[0063] According to the present invention, the concentration of the organic dye is 1-3 mM.

[0064] The present invention will be described in detail below by way of examples.

[0065] The raw materials used in the examples and comparative examples are all commercially available products.

[0066] Example 1

[0067] 1) Dispersing silica nanospheres with an average diameter of 150 nm and dopamine in a buffer solution, stirring for 1 hour, centrifuging at 5000 rpm for 0.1 hour, washing, and vacuum drying at 60°C for 12 hours to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine, and buffer solution is 1 g:1 g:200 mL;

[0068] 2) annealing the polydopamine / silica nanospheres at 600°C for 2 h under an argon protective atmosphere to obtain a sample N / C-SiO2-T;

[0069] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2·2H2O, and L-cysteine ​​were added in sequence. The mixture was refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed three times with deionized water, and dried in vacuo at 80°C for 10 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. The mass volume ratio of N / C-SiO2-T to ethylene glycol was 1 g:650 mL, and the mass ratio of InCl3, CdCl2·2H2O, and L-cysteine ​​was 1:0.5:0.5.

[0070] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 5wt% HF aqueous solution for 12 hours, centrifuged at 5000 rpm for 0.2 hours, washed, and vacuum dried at 80°C for 10 hours to obtain hollow nanospheres CdIn2S4-N / C-2-T-1, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:300 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:3.5:18.

[0071] Figure 1 is a TEM image of the photocathode material obtained in Example 1 of the present invention, Figure 1 It can be seen that the structure of the prepared CdIn2S4-N / C-2-T-1 is hollow and circular.

[0072] Example 2

[0073] 1) Dispersing silica nanospheres with an average diameter of 100 nm and dopamine in a buffer solution, stirring for 2 h, centrifuging at 5000 rpm for 0.1 h, washing, and vacuum drying at 60° C. for 24 h to obtain polydopamine / silica nanospheres, wherein the mass-to-volume ratio of silica nanospheres, dopamine, and buffer solution is 1 g:0.5 g:500 mL;

[0074] 2) annealing the polydopamine / silica nanospheres at 800°C for 4 h under a nitrogen atmosphere to obtain a sample N / C-SiO2-T;

[0075] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2·2H2O, and L-cysteine ​​were added in sequence. The mixture was refluxed at 200°C for 1 hour, centrifuged at 5000 rpm for 0.2 hour, washed three times with deionized water, and dried in vacuo at 80°C for 36 hours to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. The mass volume ratio of N / C-SiO2-T to ethylene glycol was 1 g:450 mL, and the mass ratio of InCl3, CdCl2·2H2O, and L-cysteine ​​was 1:0.5:2.

[0076] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 4wt% HF aqueous solution for 24 hours, centrifuged at 5000 rpm for 0.2 hours, washed with deionized water three times, and dried at 80°C for 36 hours to obtain hollow nanospheres CdIn2S4-N / C-2-T-2, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:200 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:3:15.

[0077] Example 3

[0078] 1) Silica nanospheres with an average diameter of 200 nm and dopamine were dispersed in 300 mL of buffer solution, stirred for 1.5 h, centrifuged at 5000 rpm for 0.15 h, washed three times with deionized water, and vacuum dried at 60°C for 24 h to obtain polydopamine / silica nanospheres, wherein the mass volume ratio of silica nanospheres, dopamine, and buffer solution was 1 g:2 g:300 mL;

[0079] 2) annealing the polydopamine / silica nanospheres at 700° C. for 2 h under an argon protective atmosphere to obtain a sample N / C-SiO2-T;

[0080] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2·2H2O, and L-cysteine ​​were added in sequence. The mixture was refluxed at 200°C for 1 h, centrifuged at 5000 rpm for 0.2 h, washed three times with deionized water, and dried in vacuo at 80°C for 30 h to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. The mass volume ratio of N / C-SiO2-T to ethylene glycol was 1 g:850 mL, and the mass ratio of InCl3, CdCl2·2H2O, and L-cysteine ​​was 1:0.5:1.

[0081] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 2wt% HF aqueous solution for 36 hours, centrifuged at 5000 rpm for 0.2 hours, washed with deionized water three times, and dried at 80°C for 24 hours to obtain hollow nanospheres CdIn2S4-N / C-2-T-3, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:400 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:4:20.

[0082] Example 4

[0083] 1) Silica nanospheres with an average diameter of 50 nm and dopamine were dispersed in a buffer solution, stirred for 1 hour, centrifuged at 5000 rpm for 0.1 hour, washed three times with deionized water, and vacuum dried at 60°C for 24 hours to obtain polydopamine / silica nanospheres, wherein the mass-to-volume ratio of silica nanospheres, dopamine, and buffer solution was 1 g:0.4 g:150 mL;

[0084] 2) annealing the polydopamine / silica nanospheres at 700°C for 3 h under a nitrogen atmosphere to obtain a sample N / C-SiO2-T;

[0085] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2·2H2O, and L-cysteine ​​were added in sequence. The mixture was refluxed at 200°C for 1 hour, centrifuged at 5000 rpm for 0.1 hour, washed, and dried in vacuo at 80°C for 24 hours to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. The mass volume ratio of N / C-SiO2-T to ethylene glycol was 1 g:300 mL, and the mass ratio of InCl3, CdCl2·2H2O, and L-cysteine ​​was 1:0.5:1.5.

[0086] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 7wt% HF aqueous solution for 16 hours, centrifuged at 5000 rpm for 0.2 hours, washed with deionized water three times, and vacuum dried at 80°C for 24 hours to obtain hollow nanospheres CdIn2S4-N / C-2-T-4, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:100 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:2:5.

[0087] Example 5

[0088] 1) Silica nanospheres with an average diameter of 300 nm and dopamine were dispersed in a buffer solution, stirred for 1 hour, centrifuged at 5000 rpm for 0.2 hour, washed three times with deionized water, and dried at 90°C for 24 hours to obtain polydopamine / silica nanospheres, wherein the mass-to-volume ratio of silica nanospheres, dopamine, and buffer solution was 1 g:3 g:600 mL;

[0089] 2) annealing the polydopamine / silica nanospheres at 900° C. for 2 h under an argon atmosphere to obtain a sample N / C-SiO2-T;

[0090] 3) N / C-SiO2-T was uniformly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2·2H2O, and L-cysteine ​​were added in sequence. The mixture was refluxed at 200°C for 1 hour, centrifuged at 5000 rpm for 0.2 hour, washed three times with deionized water, and dried at 80°C for 24 hours to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. The mass volume ratio of N / C-SiO2-T to ethylene glycol was 1 g:1000 mL, and the mass ratio of InCl3, CdCl2·2H2O, and L-cysteine ​​was 1:0.5:1.

[0091] 4) The above-mentioned CdIn2S4-N / C-SiO2-2-T solid nanospheres were etched with 3wt% HF aqueous solution for 48 hours, centrifuged at 500 rpm for 0.2 hours, washed with deionized water three times, and dried at 100°C for 36 hours to obtain hollow nanospheres CdIn2S4-N / C-2-T-5, wherein the mass volume ratio of CdIn2S4-N / C-SiO2-2-T and HF aqueous solution was 1 g:500 mL, and the weight ratio of polydopamine, amorphous carbon and CdIn2S4 in CdIn2S4-N / C-2-T-1 was 1:5:30.

[0092] Test Case

[0093] The photocathode materials prepared in the examples and comparative examples were tested for preparing ethylene glycol.

[0094] The photocathode was prepared as follows:

[0095] The hollow nanospheres CdIn2S4-N / C-2-T were dispersed in 0.5 mL of 0.5 wt% Nafion ethanol solution and then added dropwise to a 1×2 cm 2 The photocathode was obtained by placing the film on carbon paper and drying it in a vacuum drying oven at 80 degrees for 8 hours.

[0096] Ethylene glycol is prepared according to the following steps:

[0097] A photoelectrode and a cathode electrode were installed in the anode chamber and cathode chamber of a 500mL double-cell quartz photoelectrolytic cell, respectively, and 180mL of a 0.1M KHCO3 aqueous solution was added to each chamber. 1mM Eosin Y was added to the anode chamber. A silicon solar cell with a voltage of 1.6V was connected to the electrodes, and the voltage was adjusted to 0.4-1.2V. Under light conditions, CO2 was introduced into the electrolytic cell for reaction to obtain ethylene glycol, ethanol, acetic acid and formic acid products.

[0098] Test Example 1

[0099] A BiVO4 / Ni photoanode and an electrode comprising the photocathode material prepared in Example 1 were used as the photocathode. A silicon solar cell provided external power at 0.8V. A 500mL dual-cell quartz photoelectrolyzer was equipped with a photoelectrode and a cathode, respectively, in the anode and cathode compartments. 180mL of a 0.1M KHCO3 aqueous solution was added to each compartment. Eosin Y was added to the anode compartment at a concentration of 1mM. The air in the water was replaced with CO2 gas for 30 minutes, and the reactor was sealed. The reactor was connected to the silicon solar cell and CO2 was continuously introduced into the reactor under illumination. After 8 hours of reaction, the total amount of ethylene glycol organic matter reached 165mg, and the ethylene glycol selectivity was 65%.

[0100] Test Example 2

[0101] The method of Test Example 1 was followed, except that the electrode contained the photocathode material prepared in Example 2 as the photocathode, and the voltage was 0.4V.

[0102] Test Example 3

[0103] The method of Test Example 1 was followed, except that the voltage was 0.5V.

[0104] Test Example 4

[0105] The method of Test Example 1 was followed, except that the voltage was 0.6V.

[0106] Test Example 5

[0107] The method of Test Example 1 was followed, except that the voltage was 0.7V.

[0108] Test Example 6

[0109] The method of Test Example 1 was followed, except that the voltage was 0.9V.

[0110] Test Example 7

[0111] The method of Test Example 1 was followed, except that the voltage was 1V.

[0112] Test Example 8

[0113] The method of Test Example 1 was followed, except that the voltage was 1.1V.

[0114] Test Example 9

[0115] The method of Test Example 1 was followed, except that the voltage was 1.2 V and Nile red was added to the anode chamber.

[0116] Test Example 10

[0117] The method of Test Example 1 was followed, except that the voltage was 0.8 V and methyl violet was added to the anode chamber.

[0118] Test Example 11

[0119] According to the method of Test Example 1, except that the voltage is 0.8 V.

[0120] Test conditions: The liquid phase product prepared in Test Examples 1-11 is detected and quantified by nuclear magnetic resonance hydrogen spectrum.

[0121] The specific test method is that the liquid phase product is tested and quantitatively analyzed by HNMR analysis, using D2O of 7.0395 mM DMSO as an internal standard, and using double resonance decoupling water peak suppression technology. 1 HNMR analysis, using D2O of 7.0395 mM DMSO as an internal standard, and using double resonance decoupling water peak suppression technology.

[0122] The results are shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] As can be seen from Table 1, the photo-cathode prepared by the application has good light absorption performance and catalytic carbon dioxide reduction ability when used for preparing ethylene glycol, and has high selectivity for ethylene glycol.

[0127] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A photocathode material, characterized in that: The photocathode material includes polydopamine, amorphous carbon and CdIn2S4; The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(2-5):(5-30).

2. The photocathode material according to claim 1, wherein The weight ratio of the polydopamine, amorphous carbon and CdIn2S4 is 1:(3-4):(15-20).

3. A method for preparing a photocathode material, characterized in that: The preparation method comprises the following steps: 1) dispersing silica nanospheres and dopamine in a buffer solution for a first reaction to obtain polydopamine / silica nanospheres; 2) Annealing the polydopamine / silica nanospheres under a protective atmosphere to obtain a sample N / C-SiO2-T; 3) The N / C-SiO2-T was evenly dispersed in ethylene glycol. Under stirring, InCl3, CdCl2•2H2O, and L-cysteine ​​were added in sequence to carry out a second reaction to obtain solid nanospheres CdIn2S4-N / C-SiO2-2-T. 4) The CdIn2S4-N / C-SiO2-2-T solid nanospheres are subjected to a third reaction with an HF aqueous solution to obtain hollow nanospheres CdIn2S4-N / C-2-T.

4. The method for preparing a photocathode material according to claim 3, wherein: In step 1), the mass-to-volume ratio of the silica nanospheres, dopamine, and buffer solution is 1 g: (0.4-3) g: (150-600) mL.

5. The method for preparing a photocathode material according to claim 3, wherein: The average diameter of the silicon dioxide nanospheres is 50-300 nm.

6. The method for preparing a photocathode material according to claim 3, wherein: In step 2), the annealing conditions include: temperature of 600-900° C. and time of 2-4 hours.

7. The method for preparing a photocathode material according to claim 3, wherein: The protective atmosphere is selected from argon and / or nitrogen.

8. The method for preparing a photocathode material according to any one of claims 3 to 7, wherein: In step 3), the mass volume ratio of the N / C-SiO2-T and ethylene glycol is 1 g: (300-1000) mL.

9. The method for preparing a photocathode material according to any one of claims 3 to 7, wherein: In step 3), the mass ratio of InCl 3 , CdCl 2 • 2H 2 O and L-cysteine ​​is 1: (0.5-1): (0.5-2).

10. The method for preparing a photocathode material according to any one of claims 3 to 7, wherein: In step 4), the mass volume ratio of the CdIn2S4-N / C-SiO2-2-T and the HF aqueous solution is 1 g: (100-500) mL.

11. The method for preparing a photocathode material according to claim 10, wherein: The concentration of the HF aqueous solution is 1-7 wt %.

12. A photocathode, characterized in that: The photocathode comprises the photocathode material according to claim 1 or the photocathode material prepared by the preparation method according to any one of claims 3 to 11.

13. Use of the photocathode according to claim 12 in the preparation of ethylene glycol.

14. A method for preparing ethylene glycol, characterized in that: The method comprises: Under light conditions, CO2 is introduced into an electrolytic cell for reaction to obtain ethylene glycol; wherein the photocathode in the electrolytic cell is the photocathode according to claim 12.

15. The preparation method according to claim 14, wherein The electrolytic cell further includes a photoanode, which is selected from any one of BiVO4 / Ni, BiVO4 / Cu, BiVO4 / Al and BiVO4 / Ti.

16. The preparation method according to claim 14, wherein The electrolytic cell further comprises an electrolyte, which is an inorganic salt solution selected from an aqueous solution of KHCO3 and / or NaHCO3.

17. The preparation method according to claim 16, wherein The concentration of the inorganic salt solution is 0.05-0.2 mol / L.

18. The preparation method according to claim 14, wherein The voltage between the photocathode and the photoanode is 0.6-1.3V.

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