A method for preparing a Cu-Cu2O composite catalyst, its product and application
By preparing Cu-Cu2O composite catalysts, the potential range of formaldehyde oxidation was broadened and the formaldehyde adsorption capacity of the catalyst was improved, solving the problem of potential limitation of Cu-based catalysts in formaldehyde oxidation reaction, and realizing high current density and efficient hydrogen production.
Patent Information
- Application Number
- CN202410722485.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-05
- Publication Date
- 2025-12-05
- Estimated Expiration
- 2044-06-05
AI Technical Summary
Existing Cu-based catalysts have a limited potential range in the formaldehyde oxidation reaction, resulting in low hydrogen production current density and difficulty in adapting to voltage fluctuations in renewable energy sources, which limits the efficiency of hydrogen production through water electrolysis.
Cu-Cu2O composite catalysts were prepared by reducing CuO with paraformaldehyde solution, forming a plate-like flower cluster structure, which broadened the formaldehyde oxidation potential range and improved the formaldehyde adsorption capacity of the catalyst.
Achieving industrial-grade current density formaldehyde oxidation for hydrogen production at high potentials, widening the potential range to 1.2V, improving hydrogen production efficiency, reducing energy consumption, and adapting to voltage fluctuations in renewable energy sources.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a preparation method of a Cu-Cu2O composite catalyst, a product thereof and application. BACKGROUND
[0002] Hydrogen, as a clean and sustainable energy, is expected to replace traditional fossil fuels to solve the energy crisis and environmental pollution. Electrolysis of water combined with renewable energy is one of the most efficient and economical ways to produce hydrogen. However, the anodic oxygen evolution reaction involved in the process is a four-electron proton transfer process with slow kinetics, which requires a high voltage (>1.23 V vs. RHE) to drive, greatly reducing the efficiency of hydrogen production by electrolysis of water. In addition, the oxygen generated at the anode has low added value, and there is a risk of hydrogen / oxygen cross. Using the anodic formaldehyde oxidation reaction (thermodynamic potential of-0.22 V vs. RHE) instead of the oxygen evolution reaction can realize the co-production of hydrogen and formate at the anode, improving the hydrogen production efficiency of the system while reducing the energy consumption of the system. This system is expected to become a new generation of efficient electrocatalytic hydrogen production system.
[0003] Cu-based materials are considered to be one of the most effective formaldehyde oxidation hydrogen production catalysts (Energy Environ. Sci., 2022, 15, 4175), in which Cu 0 is considered to be the adsorption site and catalytic site of formaldehyde, and Cu + is considered to help the dissociation of C-H bond (Chem 2023, 9, 963-977). However, the potential range of the current electrocatalytic formaldehyde oxidation reaction is limited to below 0.6 V, mainly because Cu-based catalysts will undergo oxidation from 0 valence to +1 valence at 0.5 V to 0.7 V, and oxidation from +1 valence to +2 valence at 0.8 V to 1.0 V, resulting in catalyst deactivation, which greatly restricts the hydrogen production current density of the reaction (<1 Acm -2 ), and is difficult to adapt to the voltage fluctuation characteristics of renewable energy driving, which seriously limits the application of the system. SUMMARY
[0004] The purpose of the present application is to provide a preparation method of a Cu-Cu2O composite catalyst, a product thereof and application, and the prepared Cu-Cu2O composite catalyst can be applied to formaldehyde oxidation hydrogen production, which can widen the potential range of formaldehyde oxidation and improve the hydrogen production efficiency of formaldehyde oxidation.
[0005] The present application provides the following technical solutions:
[0006] A preparation method of a Cu-Cu2O composite catalyst, the preparation method comprising:
[0007] (1) dissolving sodium hydroxide to obtain a base solution, adding ammonium persulfate to the base solution to obtain a standing solution;
[0008] (2) the foamed copper is placed in a standing liquid to react, and CuO foam is obtained;
[0009] (3) the CuO foam is placed in an alkaline paraformaldehyde solution to react at room temperature, and a Cu-Cu2O composite catalyst is obtained.
[0010] Further, in step (1), the concentration of the sodium hydroxide solution in the bottom liquid is 2-4 mol / L, and the dissolution temperature is 60-80 DEG C; the concentration of ammonium persulfate in the standing liquid is 0.2-0.4 mol / L. In step (1), by adjusting the concentration of the sodium hydroxide solution and the concentration of ammonium persulfate, the subsequent foamed copper generates CuO foam: when the concentration of ammonium persulfate is lower than 0.2 mol / L, and the concentration of sodium hydroxide is higher than 4 mol / L, copper hydroxide is likely to be generated.
[0011] Further, in step (2), the reaction is kept at 60-80 DEG C for 20-40 min.
[0012] Further, in step (3), the concentration of paraformaldehyde in the alkaline paraformaldehyde solution is 10-30 g / L, and the reaction time is 8-12 h. When the concentration of paraformaldehyde is lower than 10 g / L, the performance of the prepared Cu-Cu2O composite catalyst gradually decreases, and when the concentration of paraformaldehyde is 10-30 g / L, the performance of the Cu-Cu2O composite catalyst changes little. The alkaline paraformaldehyde solution comprises potassium hydroxide, and the concentration of the potassium hydroxide is 1 mol / L.
[0013] The application further provides a Cu-Cu2O composite catalyst prepared by the above preparation method.
[0014] The Cu-Cu2O composite catalyst has a sheet-like flower cluster structure.
[0015] The application further provides an application of the above Cu-Cu2O composite catalyst in the oxidation of formaldehyde to produce hydrogen.
[0016] Compared with the traditional water electrolysis reaction, the oxidation of formaldehyde reduces the energy consumption of the system and improves the economic benefits of the anode product, providing a new scheme for formaldehyde wastewater treatment and efficient hydrogen production; and the Cu-Cu2O catalyst provided by the application has strong formaldehyde adsorption capacity, which ensures high coverage of formaldehyde molecules on the catalyst surface at high potential, avoids the poisoning of active sites by OH - , and effectively inhibits the oxidation competition reaction of the catalyst at high potential.
[0017] Further, the formaldehyde oxidation potential interval is 0-1.2 V.
[0018] Further, the application further discloses application of the Cu-Cu2O composite catalyst in hydrogen production by formaldehyde oxidation.
[0019] Compared with the prior art, the application has the advantages that:
[0020] The Cu-Cu2O composite catalyst is prepared by reducing CuO with a paraformaldehyde solution, and the preparation method is simple. -2 The Cu-Cu2O composite catalyst prepared by the application can realize hydrogen production by formaldehyde oxidation at an industrial current density (>=1 Acm-2) at a high potential (>=0.6 V), and the formaldehyde oxidation potential range is widened to 1.2 V, and the hydrogen production efficiency of the reaction is improved, thereby providing a solution for low-energy-consumption and high-efficiency green hydrogen production. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 An X-ray diffraction pattern of the Cu-Cu2O catalyst prepared in Example 1.
[0022] Figure 2 An X-ray photoelectron spectroscopy pattern of the Cu-Cu2O catalyst prepared in Example 1.
[0023] Figure 3 A scanning electron microscope pattern of the Cu-Cu2O catalyst prepared in Example 1.
[0024] Figure 4 A linear sweep voltammetry curve of the Cu-Cu2O catalyzed formaldehyde oxidation, wherein, Figure 4 (a) in the linear sweep voltammetry curve of the Cu-Cu2O in the formaldehyde electrolyte with or without formaldehyde, Figure 4 (b) in the linear sweep voltammetry curve of the Cu-Cu2O in the formaldehyde electrolyte with different formaldehyde concentrations.
[0025] Figure 5 A linear sweep voltammetry curve of the Cu (Comparative Example 2), Cu2O (Comparative Example 1) and Cu-Cu2O (Example 1) catalyzed formaldehyde oxidation in a three-electrode system with 1M KOH and 20g / L formaldehyde solution as electrolyte.
[0026] Figure 6 A Faraday efficiency of hydrogen production by Cu-Cu2O catalyzed formaldehyde oxidation under different voltages. Figure 6X-ray diffraction patterns of Cu-Cu2O catalysts before and after different voltage response in (a) of FIG. 1. Figure 6
[0027] Figure 7 The open-circuit voltage test curves of Cu (Comparative Example 2), Cu2O (Comparative Example 1) and Cu-Cu2O (Example 1) are shown in FIG. 2.
[0028] Figure 8 The linear sweep voltammetry curves of Cu-Cu2O catalyst prepared in Examples 1-3 and Comparative Examples 3-5 for formaldehyde oxidation are shown in FIG. 3. DETAILED DESCRIPTION
[0029] Example 1
[0030] The preparation method of the Cu-Cu2O composite catalyst provided in this example is as follows:
[0031] The foam copper was cut into a size of 1 cm*3 cm*0.5 cm and cleaned by ultrasonic in acetone, 2 mol / L HCl, deionized water and anhydrous ethanol for 10 min, respectively. 7.2 g of sodium hydroxide was weighed and dissolved in 60 mL of deionized water, and stirred uniformly in a water bath at 60°C to obtain a base solution. 2.74 g of ammonium persulfate was weighed and dissolved in the base solution to obtain a standing solution. The cleaned foam copper was placed in the standing solution and incubated at 60°C for 30 min to obtain CuO foam. The CuO was placed in a 1 mol / L potassium hydroxide solution of paraformaldehyde at room temperature for 10 h, and the concentration of paraformaldehyde was 10 g / L to obtain the composite catalyst Cu-Cu2O.
[0032] X-ray diffraction analysis was performed on the Cu-Cu2O prepared in Example 1 Figure 1 ), and characteristic diffraction peaks of Cu and Cu2O were found, which can be indexed to standard PDF cards (04-0836, 05-0667), indicating the successful preparation of the Cu-Cu2O catalyst.
[0033] X-ray photoelectron spectroscopy analysis was performed on the Cu-Cu2O prepared in Example 1, and the contents of Cu and Cu2O in the Cu-Cu2O were found to be 42.3% and 57.7%, respectively Figure 2 ).
[0034] Scanning electron microscope analysis was performed on the Cu-Cu2O prepared in Example 1, and it was found that the Cu-Cu2O had a flaky flower cluster structure Figure 3 ).
[0035] Application Example 1
[0036] The Cu-Cu₂O prepared in Example 1 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu-Cu₂O, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration was 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0037] The electrocatalytic performance of electrolytes with different paraformaldehyde concentrations (0 g / L-30 g / L) was tested.
[0038] Linear sweep voltammetry curve ( Figure 4 (a) The dashed line shows that when the anolyte is pure potassium hydroxide, Cu-Cu₂O oxidation peaks of 0-valent to 1-valent copper are detected at 0.5V-0.7V, and oxidation peaks of 1-valent to 2-valent copper are detected above 0.8V, indicating the oxidation reaction of copper at the corresponding voltages. When the anolyte contains formaldehyde ( Figure 4 The solid line in (a) and Figure 8 The Cu-Cu₂O catalyst exhibited excellent formaldehyde oxidation activity, reaching 1200 mA cm⁻¹ when the formaldehyde concentration was 20 g / L and the applied voltage was 1.0 V. -2 The current density. Furthermore, linear sweep voltammetry curves of different concentrations of paraformaldehyde (1 g / L, 2 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L and 30 g / L) were obtained. Figure 4 (b) in the paper demonstrates that the formaldehyde oxidation voltage can be broadened with the increase of paraformaldehyde concentration. When the paraformaldehyde concentration is greater than 5 g / L, hydrogen production with a voltage higher than 0.6 V can be achieved, and when the paraformaldehyde concentration is greater than 15 g / L, hydrogen production with a voltage higher than 1.0 V can be achieved.
[0039] Testing the Faraday efficiency of Cu-Cu2O catalytic formaldehyde oxidation to hydrogen production at different voltages:
[0040] Figure 6 (a) shows that the catalyst Cu-Cu2O has a hydrogen production faradaic efficiency of over 95% in the voltage range of 0.2V-1.2V, and the hydrogen production faradaic efficiency is 97.51% when the applied voltage is 1.2V.
[0041] X-ray diffraction analysis was performed on the Cu-Cu2O catalyst after electrolysis at 0.6V and 1.0V. Figure 6 In (b) of the study, it was found that the characteristic diffraction peaks did not change significantly, proving that no catalyst oxidation deactivation competing reaction would occur at an electrolysis voltage higher than 0.6V.
[0042] Test open circuit voltage:
[0043] Open-circuit voltage test Figure 7 ) shows that the maximum open-circuit voltage difference of Cu-Cu2O is 0.570 V after adding formaldehyde into the electrolyte, indicating that Cu-Cu2O has strong adsorption capacity for formaldehyde molecules, which provides guarantee for formaldehyde adsorption and oxidation at high voltage.
[0044] Example 2
[0045] The difference between Example 2 and Example 1 is that the concentration of paraformaldehyde in Example 2 is 15 g / L.
[0046] The Cu-Cu2O prepared in Example 2 was used as a formaldehyde oxidation electrocatalyst to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, which was placed in the anode. The anode electrolyte composition was 25 ml of paraformaldehyde solution containing 1 mol / L potassium hydroxide, and the paraformaldehyde concentration was 20 g / L. The cathode electrolyte composition was 25 ml of 1 mol / L potassium hydroxide solution.
[0047] Linear sweep voltammetry curves Figure 8 ) show that the formaldehyde oxidation performance of Cu-Cu2O prepared under the condition of a paraformaldehyde concentration of 15 g / L in the voltage range of 0-1.0 V is not different from that of Example 1.
[0048] Example 3
[0049] The difference between Example 3 and Example 1 is that the concentration of paraformaldehyde in Example 3 is 20 g / L.
[0050] The Cu-Cu2O prepared in Example 3 was used as a formaldehyde oxidation electrocatalyst to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, which was placed in the anode. The anode electrolyte composition was 25 ml of paraformaldehyde solution containing 1 mol / L potassium hydroxide, and the paraformaldehyde concentration was 20 g / L. The cathode electrolyte composition was 25 ml of 1 mol / L potassium hydroxide solution.
[0051] Linear sweep voltammetry curves Figure 8 ) show that the formaldehyde oxidation performance of Cu-Cu2O prepared under the condition of a paraformaldehyde concentration of 20 g / L in the voltage range of 0-1.0 V is not different from that of Example 1.
[0052] Comparative Example 1
[0053] Weigh 10g of sodium hydroxide and 3.5g of potassium persulfate and dissolve them in 100mL of deionized water, stirring at room temperature. Place the cleaned copper foam in the above solution and react at room temperature for 30min to obtain Cu(OH)2. Place the Cu(OH)2 in a tube furnace and calcine at 550℃ for 3h under an Ar gas atmosphere, with a heating rate of 1℃ / min, to obtain Cu2O.
[0054] The Cu₂O prepared in Comparative Example 1 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu₂O, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration: 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0055] Linear sweep voltammetry curve ( Figure 5 This indicates that Cu2O does not have significant formaldehyde oxidation activity.
[0056] Open circuit voltage test ( Figure 7 The results showed that Cu2O exhibited the smallest open-circuit voltage difference of 0.013V after the addition of formaldehyde to the electrolyte, indicating that Cu2O has a poor adsorption capacity for formaldehyde molecules.
[0057] Comparative Example 2
[0058] Cu2O prepared in the comparative example was calcined at 300℃ for 2 hours in a tube furnace under a 5% H2 / Ar gas atmosphere with a heating rate of 2℃ / min to obtain Cu.
[0059] The Cu prepared in Comparative Example 2 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration: 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0060] Linear sweep voltammetry curve ( Figure 5 This indicates that Cu exhibits moderate formaldehyde oxidation activity at voltages below 0.7 V. At a voltage of 0.6 V, the current density is 304 mA / cm². -2 When the voltage is above 0.7V, Cu oxidation occurs, which inhibits formaldehyde oxidation activity.
[0061] Open circuit voltage test ( Figure 7 The results showed that Cu exhibited a moderate open-circuit voltage difference of 0.372V after the addition of formaldehyde to the electrolyte, indicating that Cu has a moderate adsorption capacity for formaldehyde molecules.
[0062] Comparative Example 3
[0063] The difference from Example 1 is that the paraformaldehyde concentration in Comparative Example 3 is 1 g / L.
[0064] The Cu-Cu₂O prepared in Comparative Example 3 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration was 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0065] Linear sweep voltammetry curve ( Figure 8 The results show that Cu-Cu2O prepared with a paraformaldehyde concentration of 1 g / L has the lowest formaldehyde oxidation current in the voltage range of 0-1.0 V.
[0066] Comparative Example 4
[0067] The difference from Example 1 is that the paraformaldehyde concentration in Comparative Example 4 is 2 g / L.
[0068] The Cu-Cu₂O prepared in Comparative Example 4 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration was 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0069] Linear sweep voltammetry curve ( Figure 8 The results show that Cu-Cu2O prepared with a paraformaldehyde concentration of 2 g / L has higher formaldehyde oxidation performance than Comparative Example 3 in the voltage range of 0-1.0 V.
[0070] Comparative Example 5
[0071] The difference from Example 1 is that the paraformaldehyde concentration in Comparative Example 5 is 5 g / L.
[0072] The Cu-Cu₂O prepared in Comparative Example 5 was used as the electrocatalyst for formaldehyde oxidation to construct a three-electrode system for electrochemical testing. The anode electrode was Cu, the cathode electrode was a carbon rod, and the reference electrode was Hg / HgO, placed at the anode. The anolyte consisted of 25 ml of a paraformaldehyde solution containing 1 mol / L potassium hydroxide (paraformaldehyde concentration: 20 g / L), and the cathode electrolyte consisted of 25 ml of a 1 mol / L potassium hydroxide solution.
[0073] Linear sweep voltammetry curves (LSV) showed that the Cu-Cu20 prepared with 5 g / L of paraformaldehyde had higher formaldehyde oxidation performance than Comparative Example 4 but lower than Example 1 in the voltage range of 0-1.0 V. Figure 8
[0074] The above examples are only used to explain the inventive concept of the present application, and are not intended to limit the protection scope of the present application. Any simple modification, equivalent change and modification made to the above examples according to the technical and method of the present application still belong to the scope of the technical and method of the present application.
Claims
1. Application of Cu-Cu2O composite catalyst in hydrogen production by formaldehyde oxidation, characterized in that, The preparation method of the Cu-Cu2O composite catalyst comprises the following steps: (1) dissolving sodium hydroxide to obtain a base solution, adding ammonium persulfate to the base solution to obtain a standing solution; (2) reacting foamed copper in the standing solution to obtain CuO foam; (3) reacting the CuO foam in an alkaline paraformaldehyde solution at room temperature to obtain the Cu-Cu2O composite catalyst; In step (3), the concentration of paraformaldehyde in the alkaline paraformaldehyde solution is 10 g / L-30 g / L, and the reaction time is 8 h-12 h; The anode electrode in the hydrogen production by formaldehyde oxidation is the Cu-Cu2O composite catalyst, the anode electrolyte in the hydrogen production by formaldehyde oxidation is a paraformaldehyde solution containing 1 mol / L potassium hydroxide, and the potential range of the hydrogen production by formaldehyde oxidation is 0-1.2 V.
2. The application of Cu-Cu20 composite catalyst in hydrogen production by formaldehyde oxidation according to claim 1, characterized in that, In step (1), the concentration of sodium hydroxide solution in the base solution is 2 mol / L-4 mol / L, and the dissolving temperature is 60℃-80℃; the concentration of ammonium persulfate in the standing solution is 0.2 mol / L-0.4 mol / L.
3. The use of the Cu-Cu20 composite catalyst according to claim 1 in the hydrogen production by formaldehyde oxidation, characterized in that, In step (2), the reaction is carried out at 60℃-80℃ for 20 min-40 min.
4. The use of the Cu-Cu20 composite catalyst according to claim 1 in the hydrogen production by formaldehyde oxidation, characterized in that, The Cu-Cu2O composite catalyst has a sheet-like flower cluster structure.