A high-performance CuO photoelectric cathode film of a thiourea-assisted loaded copper electrocatalyst and a preparation method and application thereof
By preparing CuO/Cu photocathode films and using thiourea-assisted copper electrocatalysts, the problems of photostability and hydrogen evolution activity of CuO photocatalysts were solved, achieving high-efficiency photoelectrochemical performance and hydrogen production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2024-07-29
- Publication Date
- 2026-06-16
AI Technical Summary
CuO photocatalysts suffer from low photostability and photodecomposition in photoelectrochemical cells, limiting their application as photocathodes. Furthermore, metallic copper is generally not an effective electrocatalyst for hydrogen evolution reaction.
Cu(OH)₂ nanowire thin films were prepared by wet chemical oxidation, and then CuCl₂ and thiourea were impregnated in ethylene glycol monomethyl ether solution. Subsequently, the films were annealed in a tube furnace to form CuO/Cu photocathode thin films, with metallic copper loaded as a modifying material.
It improves the efficiency of photogenerated electron-hole separation, reduces the recombination rate, enhances photoelectrochemical performance, increases photocurrent density and hydrogen production rate under visible light, and reduces cost and operational complexity.
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Figure CN118957660B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photoelectrochemical technology, specifically relating to a high-performance CuO photocathode thin film (i.e., CuO / Cu photocathode thin film) with thiourea-assisted copper electrocatalyst, its preparation method, and its application. Background Technology
[0002] In recent years, the use of fossil fuels has led to a series of environmental problems, including smog, acid rain, and global warming. Furthermore, the non-renewable nature of fossil fuels severely limits their use. Therefore, finding a clean, efficient, and renewable new energy source is an urgent problem to be solved. Photoelectric chemical cells, which address energy shortages, have become a focus of attention. Photoelectric water splitting to produce hydrogen converts solar energy into storable chemical energy, representing a major means of solving environmental and energy problems in the 21st century.
[0003] CuO is an inorganic, non-toxic p-type semiconductor with an ideal narrow bandgap of 1.2–1.7 eV. Compared to other photoactive metal oxides, it exhibits strong visible light absorption, making it a very promising material for solar water splitting. Narrow-bandgap CuO is one of the few photocatalysts exhibiting high photocatalytic activity for solar water splitting (HER) under simulated sunlight irradiation, especially when combined with other photocatalysts. Although CuO is considered a promising ceramic oxide electrode for solar water splitting due to its narrow bandgap, its low photostability or photodegradation hinders its use as a photocathode in PEC cells.
[0004] Copper has long been considered an ineffective electrocatalyst for the hydrogen evolution reaction (HER), and it is typically used as an electrocatalyst for carbon dioxide reduction. However, recent studies have reported that copper also exhibits high HER activity in neutral solutions. Therefore, if the particle size and loading of copper can be reasonably controlled, copper can also be used as a modifier for CuO. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing and applying CuO / Cu photocathode thin films. This method has the advantages of being simple to prepare, easy to operate, low in cost, and easy to control experimental conditions.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst is prepared by the following steps:
[0008] 1) Dissolve sodium hydroxide and potassium persulfate in deionized water, and place copper foil with a purity of 99.9% into it to obtain the precursor Cu(OH)2 nanowire film by wet chemical oxidation.
[0009] 2) Dissolve CuCl2 and thiourea in ethylene glycol monomethyl ether to obtain an ethylene glycol monomethyl ether solution containing CuCl2 and thiourea;
[0010] 3) The Cu(OH)2 nanowire film obtained in step 1) is immersed in a solution of ethylene glycol monomethyl ether containing CuCl2 and thiourea. The resulting Cu(OH)2 nanowire film loaded with copper electrocatalyst precursor is annealed in a tube furnace to finally obtain a dense CuO / Cu photocathode film.
[0011] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, in step 1), the method for pretreating the copper foil with a purity of 99.9% before use is as follows: the copper foil with a purity of 99.9% is ultrasonically cleaned sequentially in acetone, ethanol, and deionized water.
[0012] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, in step 1), the molar ratio of sodium hydroxide to potassium persulfate is 1:0.125.
[0013] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, the wet chemical oxidation time in step 1) is 15 min.
[0014] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, in step 2), the mass of CuCl2 is 0.3g, the mass of thiourea is 0.14g, and the mass of ethylene glycol monomethyl ether is 10mL.
[0015] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst, in step 3), the impregnation treatment time is 1 min.
[0016] Furthermore, in the above-mentioned method for preparing a high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, in step 3), the annealing temperature is 500℃, the holding time is 10min, and the heating rate is 3℃ / min.
[0017] The application of the high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst described in any of the above-mentioned methods in photoelectrochemical water splitting.
[0018] Furthermore, the above application is carried out as follows: Under visible light irradiation in a three-electrode electrochemical workstation, a high-performance CuO photocathode film with a thiourea-assisted supported copper electrocatalyst is used as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, 0.5M sodium sulfate as the electrolyte, a 300W xenon lamp as the light source, and a sample irradiation area of 1 cm². 2 A water decomposition test was conducted.
[0019] Furthermore, in the above application, the test bias voltage is -0.6V.
[0020] The beneficial effects of this invention are:
[0021] 1. The composite catalyst structure of the CuO / Cu photocathode thin film provided by this invention makes it easier to effectively separate photogenerated electrons and holes, reduce the recombination rate, and effectively improve photoelectrochemical performance.
[0022] 2. The method for preparing CuO / Cu photocathode thin film provided by the present invention uses inexpensive and readily available copper foil as raw material, has a low annealing temperature, saves energy and reduces emissions, and is simple and convenient to operate, which greatly reduces costs and provides a new catalytic material for water decomposition, and has a good development prospect.
[0023] 3. The CuO / Cu photocathode thin film provided by this invention has a photocurrent density and stability under visible light that are about twice that of pure CuO thin film.
[0024] 4. The CuO / Cu photocathode thin film provided by this invention has a hydrogen production rate under visible light that is about 1 times that of pure CuO. Attached Figure Description
[0025] Figure 1 XRD comparison images of CuO / Cu photocathode thin film and CuO photocathode thin film.
[0026] Figure 2 The image shows a comparison of the LSVs of CuO / Cu photocathode films and CuO photocathode films.
[0027] Figure 3 A comparison of the photocurrent stability of CuO / Cu photocathode thin films and CuO photocathode thin films.
[0028] Figure 4 A comparison of hydrogen production rates between CuO / Cu photocathode films and CuO photocathode films. Detailed Implementation
[0029] 1) The copper foil with a purity of 99.9% was ultrasonically cleaned in acetone, ethanol and deionized water in sequence.
[0030] 2) Dissolve 1g of sodium hydroxide and 0.84g of potassium persulfate in 25 mL of deionized water. After stirring thoroughly, mix the two solutions. Place the cleaned copper foil with a purity of 99.9% in the solution for 15 min and then remove it to obtain Cu(OH)2 nanowire film, a precursor of CuO film.
[0031] 3) The CuO precursor Cu(OH)2 nanowire film was placed in a tube furnace and kept at 500℃ for 10 min with a heating rate of 3℃ / min. After cooling to room temperature, CuO photocathode film was obtained.
[0032] (I) Preparation method
[0033] 0.3 g CuCl2 and 0.14 g thiourea were dissolved in 10 mL ethylene glycol monomethyl ether. After thorough stirring, the Cu(OH)2 nanowire film prepared in Example 1 was immersed in the solution for 1 min and then annealed in a tube furnace at 500 °C for 10 min at a heating rate of 3 °C / min to finally obtain the CuO / Cu photocathode film.
[0034] (II) Testing
[0035] Figure 1 The image shows a comparison of the XRD patterns of the CuO photocathode film prepared in Example 1 and the CuO / Cu photocathode film prepared in Example 2. Figure 1 As can be seen, the sample exhibits six distinct diffraction peaks at 35.2°, 38.5°, 48.8°, 61.5°, 66.3°, and 67.9°, which are characteristic peaks of CuO. The sample also exhibits three distinct diffraction peaks at 43.3°, 50.4°, and 74.1°, which are characteristic peaks of elemental copper. This indicates that the prepared material is indeed CuO grown on a copper foil substrate. The diffraction peaks of the CuO / Cu photocathode film and the CuO photocathode film are almost identical, but the diffraction peaks of elemental Cu are significantly enhanced in the CuO / Cu photocathode film spectrum, indicating that the copper electrocatalyst has been successfully loaded onto the CuO film, meaning that the CuO / Cu photocathode film has been successfully prepared.
[0036] The CuO photocathode film prepared in Example 1 and the CuO / Cu photocathode film prepared in Example 2 were subjected to photocurrent, photocurrent stability and hydrogen production rate, respectively.
[0037] All electrochemical experiments were conducted under visible light irradiation in a three-electrode electrochemical workstation (Princeton Applied Research 2273). The sample photocathode film served as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and 0.5M sodium sulfate as the electrolyte. The sample irradiation area was 1 cm². 2 .
[0038] Photocurrent test: The light source was a 300W xenon lamp, and the bias voltage was -0.6V. The measured results are as follows. Figure 2 and Figure 3 The results showed that the photocurrent density and stability of the CuO / Cu photocathode film were both greater than those of the CuO photocathode film. After 2500 s, the photocurrent density of the CuO / Cu photocathode film decreased from -1.3 mA to -1.16 mA, with a loss of 11%; while the photocurrent density of the CuO photocathode film decreased from -1.19 mA to -0.64 mA, with a loss of 47%. This indicates that the photoelectrochemical performance was improved after loading Cu, suggesting that loading the CuO photocathode film with a metallic Cu electrocatalyst facilitates the rapid transfer of electrons to the electrolyte, thereby suppressing surface recombination.
[0039] All electrochemical experiments were conducted under visible light irradiation in a three-electrode electrochemical workstation (Princeton Applied Research 2273). The sample photocathode film served as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and 0.5 M sodium sulfate as the electrolyte. The sample irradiation area was 1 cm². 2 The water splitting test used a GC-1690 to detect the hydrogen production over each time period.
[0040] Hydrogen production test by water splitting: A 300 W xenon lamp was selected as the light source, with a bias voltage of -0.6 V. The results are as follows. Figure 4 As shown in the figure, the two solid lines represent the measured hydrogen production rates of the CuO photocathode film and the CuO / Cu photocathode film, respectively. After loading Cu, the hydrogen production rate of the CuO / Cu photocathode film is greater than that of the CuO photocathode film, effectively improving the hydrogen production efficiency of the CuO photocathode film. This demonstrates that the CuO / Cu photocathode film has a more effective water reduction driving force.
Claims
1. A high-performance CuO photocathode thin film with a thiourea-assisted supported copper electrocatalyst, characterized in that, Its preparation method includes the following steps: 1) Dissolve sodium hydroxide and potassium persulfate in deionized water, and place copper foil with a purity of 99.9% into it to obtain the precursor Cu(OH)2 nanowire film by wet chemical oxidation. 2) Dissolve CuCl2 and thiourea in ethylene glycol monomethyl ether to obtain an ethylene glycol monomethyl ether solution containing CuCl2 and thiourea; 3) The Cu(OH)2 nanowire film obtained in step 1) was immersed in a solution of ethylene glycol monomethyl ether containing CuCl2 and thiourea. The resulting Cu(OH)2 nanowire film loaded with copper electrocatalyst precursor was annealed in a tube furnace at 500°C for 10 min with a heating rate of 3°C / min, and finally a dense CuO / Cu photocathode film was obtained.
2. The high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst according to claim 1, characterized in that, In step 1), the method for pre-treating the copper foil with a purity of 99.9% before use is as follows: the copper foil with a purity of 99.9% is ultrasonically cleaned in acetone, ethanol, and deionized water in sequence.
3. The high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst according to claim 1, characterized in that, In step 1), the molar ratio of sodium hydroxide to potassium persulfate is 1:0.
125.
4. The high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst according to claim 1, characterized in that, In step 1), the wet chemical oxidation time is 15 min.
5. The high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst according to claim 1, characterized in that, In step 2), the mass of CuCl2 is 0.3g, the mass of thiourea is 0.14g, and the mass of ethylene glycol monomethyl ether is 10mL.
6. The high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst according to claim 1, characterized in that, In step 3), the immersion treatment time is 1 minute.
7. The application of the high-performance CuO photocathode thin film with thiourea-assisted supported copper electrocatalyst as described in any one of claims 1-6 in photoelectrochemical water splitting.
8. The application according to claim 7, characterized in that, The method is as follows: Under visible light irradiation in a three-electrode electrochemical workstation, a high-performance CuO photocathode film with a thiourea-assisted copper electrocatalyst was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 0.5M sodium sulfate, the light source was a 300W xenon lamp, and the sample irradiation area was 1 cm². 2 A water decomposition test was conducted.
9. The application according to claim 8, characterized in that, The test bias voltage is -0.6V.