Preparation method and application of double-active-site tungsten oxide-based electrode
By introducing N doping and O vacancy into tungsten oxide, N-Ov-W5O14 nanosheet array was prepared, which solved the problem of insufficient conductivity and active sites of WO3-based catalysts, and achieved efficient catalytic performance of Li-CO2 batteries.
Patent Information
- Application Number
- CN202510499493.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-07-22
AI Technical Summary
The existing WO3-based catalyst has poor intrinsic conductivity and limited active sites, which leads to its unsatisfactory catalytic activity and cannot be effectively used as a Li-CO2 battery catalyst.
By introducing N-doped and O vacant dual active sites into tungsten oxide, an N-Ov-W5O14 nanosheet array was prepared to form a dual active site tungsten oxide-based electrode, and the conductivity and number of active sites of the catalyst were improved by double defect engineering.
The Li-CO2 battery has achieved ultra-low overpotential (1.25V) and a stable cycle life of up to 2190h at low current density, improving the CRR and CER activity and reversibility of the catalyst.
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Figure CN120356952A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a preparation method of a Li-CO2 battery catalyst. Background Art
[0002] Lithium-carbon dioxide (Li-CO2) batteries have a high theoretical equilibrium potential (2.8 V) and theoretical energy density (1876 Whkg -1 , based on ), and are expected to solve the market dilemma of insufficient capacity of the current energy storage system mainly based on lithium-ion batteries. However, the kinetics of CO2 oxidation reduction and evolution reaction (CRR / CER) is slow, resulting in large overpotential, low capacity, and limited cycle life of Li-CO2 batteries. For the complex multi-electron transfer process, it is of great significance but also extremely challenging to design an efficient cathode catalyst to promote the two-way activity of CRR / CER and understand the relationship between the electronic state and performance. Therefore, there is an urgent need to develop an efficient dual-active-site cathode catalyst to accelerate the CRR and CER kinetics.
[0003] In response to the above scientific problems, scholars at home and abroad have adopted strategies such as nanostructure design and defect engineering to guide the development of cathode catalysts. Professor Sun Zhenyu anchored cadmium single atoms on nitrogen-doped carbon to achieve a low overpotential of 1.74 V through Cd-N4 coordination. The team of Academician Cheng Huiming adjusted the electron cloud density around the catalyst atoms through defect engineering to improve the adsorption with reactants. However, a single active component cannot simultaneously meet the two-way catalysis of CRR and CER. Therefore, there is an urgent need to develop an efficient and stable dual-active-site cathode catalyst to accelerate the conversion reaction kinetics and explore its reaction mechanism.
[0004] Among non-precious metal compounds, tungsten oxide (WO3) has become a strong candidate for various catalytic applications. Compared with most metal oxides, it exhibits excellent thermodynamic stability in acidic electrolytes and has a fast electron transfer rate (about 12 cm 2 V -1 s -1)。In addition, tungsten oxide exhibits various stable crystal structures, including oxygen-deficient and sub-stoichiometric tungsten oxides. Its lattice can effectively accommodate a large number of oxygen vacancies, thereby adjusting its bandgap and conductivity, enhancing its adsorption capacity for surface substances (such as CO2, H2, and NO2), and making it a material with broad application potential in catalytic and electrode technologies. Unfortunately, the poor intrinsic conductivity and limited active sites of WO3-based catalysts lead to unsatisfactory catalytic activity. Recently, strategies such as morphological design, composition optimization, and defect engineering have been adopted to adjust the conductivity and surface electronic structure and induce active sites, providing opportunities for optimizing electron transfer, regulating the adsorption energy of reaction molecules, and improving the catalytic activity of WO3. However, these design strategies still lack exploration of the catalytic mechanism and active centers, cannot provide a general standard for guiding catalyst design, and limit the rational design and activity regulation of Li-CO2 battery catalysts. Summary of the Invention
[0005] The object of the present invention is to solve the problem that the poor intrinsic conductivity and limited active sites of existing WO3-based catalysts result in unsatisfactory catalytic activity and they cannot be used as Li-CO2 battery catalysts, and to provide a preparation method and application of a tungsten oxide-based electrode with dual active sites.
[0006] A preparation method of a tungsten oxide-based electrode with dual active sites is specifically completed according to the following steps:
[0007] I. Preparation of WO3 nanosheets:
[0008] ① Dissolve Na2WO4·2H2O in deionized water, add HCl solution dropwise under stirring until the pH value of the solution is 1.5, then add NaCl and H2C2O4, and continue stirring until completely dissolved to obtain a mixed solution;
[0009] ② Transfer the mixed solution and the titanium substrate to a reaction kettle, carry out hydrothermal reaction at 140 °C - 160 °C for a period of time, cool to room temperature, and take out the sample; wash and dry the sample to obtain a WO3 nanosheet array grown on the surface of the titanium substrate;
[0010] II. Preparation of N-O v -W5O 14 nanosheets:
[0011] Place the WO3 nanosheet array grown on the surface of the titanium substrate in a tubular furnace, purge with argon until the air in the reaction chamber is removed, stop passing argon, introduce N2 into the reaction chamber and evacuate to 60 Pa, then turn on the plasma radio frequency power supply, and treat it at a temperature of 400 °C - 500 °C and a power of 500 W for 60 s - 90 s to obtain N-O v -W5O 14The nanosheets are tungsten oxide-based electrodes with dual active sites.
[0012] A tungsten oxide-based electrode with dual active sites is used as a catalyst for Li-CO2 batteries.
[0013] Principle and advantages of the present invention:
[0014] I. The present invention introduces N doping and O vacancy dual active sites (N-O v -W5O 14 ) into tungsten oxide by using dual defect engineering. As a catalyst for Li-CO2 batteries, it can simultaneously achieve excellent CER and CRR activities and improve capacity and reversibility; the self-supporting N-O v -W5O 14 nanosheet array has a rough surface, a highly porous structure, and a large surface area, which can provide fast mass and charge (Li + , CO2, etc.) transfer pathways, while avoiding the depletion of active sites caused by Li2CO3 deposition; the Li-CO2 battery based on the tungsten oxide-based electrode with dual active sites (N-O v -W5O 14 catalyst) achieves an ultra-low overpotential (1.25 V) and a stable cycle life of up to 2190 h at a current density of 20 μA cm -2 ;
[0015] II. The present invention will provide new ideas for the development of highly efficient bifunctional catalysts for Li-CO2 batteries. Brief Description of the Drawings
[0016] Figure 1 It is a schematic diagram of the preparation method of a tungsten oxide-based electrode with dual active sites of the present invention;
[0017] Figure 2 It is the SEM image of the WO3 nanosheets prepared in Step 1 of Example 1;
[0018] Figure 3 It is the SEM image of the N-O v -W5O 14 nanosheets prepared in Step 2 of Example 1;
[0019] Figure 4 It is the EDX image of the N-O v -W5O 14 nanosheets prepared in Step 2 of Example 1;
[0020] Figure 5 It is the TEM image of the N-O v -W5O 14 nanosheets prepared in Step 2 of Example 1;
[0021] Figure 6 are the XRD patterns of various samples;
[0022] Figure 7 are the EPR spectra of various samples;
[0023] Figure 8 is the structural schematic diagram of the Li-CO2 battery assembled using the catalyst;
[0024] Figure 9 are the first-cycle galvanostatic charge-discharge curves of the Li-CO2 battery assembled using various catalysts;
[0025] Figure 10 are the time-voltage curves of the Li-CO2 battery assembled using various catalysts;
[0026] Figure 11 are the rate performance curves of the Li-CO2 battery assembled using various catalysts. Detailed implementation manners
[0027] Detailed implementation manner 1: A preparation method of a dual-active-site tungsten oxide-based electrode in this implementation manner is specifically completed according to the following steps:
[0028] I. Preparation of WO3 nanosheets:
[0029] ①. Dissolve Na2WO4·2H2O in deionized water, add HCl solution dropwise under stirring until the pH value of the solution is 1.5, then add NaCl and H2C2O4, and continuously stir until completely dissolved to obtain a mixed solution;
[0030] ②. Transfer the mixed solution and the titanium substrate to a reaction kettle, perform hydrothermal reaction at 140°C to 160°C for a period of time, cool to room temperature, and take out the sample; wash and dry the sample to obtain a WO3 nanosheet array grown on the surface of the titanium substrate;
[0031] II. Preparation of N-O v -W5O 14 nanosheets:
[0032] Place the WO3 nanosheet array grown on the surface of the titanium substrate in a tube furnace, purge with argon until the air in the reaction chamber is removed, stop introducing argon, introduce N2 into the reaction chamber and evacuate to 60 Pa, then turn on the plasma radio frequency power supply, and process at a temperature of 400°C to 500°C and a power of 500 W for 60 s to 90 s to obtain N-O v -W5O 14 nanosheets, which are the dual-active-site tungsten oxide-based electrodes.
[0033] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the mass ratio of Na2WO4·2H2O to the volume of deionized water in Step ① is (3 g - 4 g):(60 mL - 80 mL). Other steps are the same as those in Specific Embodiment 1.
[0034] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is that the mass ratio of NaCl to the volume of deionized water in Step ① is (1 g - 2 g):(60 mL - 80 mL). Other steps are the same as those in Specific Embodiment 1 or 2.
[0035] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that the mass ratio of H2C2O4 to the volume of deionized water in Step ① is (1 g - 2 g):(60 mL - 80 mL). Other steps are the same as those in Specific Embodiments 1 to 3.
[0036] Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is that the concentration of the HCl solution in Step ① is 5 mol / L - 7 mol / L. Other steps are the same as those in Specific Embodiments 1 to 4.
[0037] Specific Embodiment 6: The difference between this embodiment and one of Specific Embodiments 1 to 5 is that the titanium substrate in Step ② is a titanium foil; the thickness of the titanium foil is 0.1 mm; the hydrothermal reaction time in Step ② is 14 h - 18 h. Other steps are the same as those in Specific Embodiments 1 to 5.
[0038] Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 1 to 6 is that in Step ②, the solid product is washed 2 - 4 times with deionized water and anhydrous ethanol in sequence; the drying temperature in Step ② is 50 °C - 80 °C, and the drying time is 3 h - 5 h. Other steps are the same as those in Specific Embodiments 1 to 6.
[0039] Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 1 to 7 is that the flow rate of N2 in Step ② is 20 sccm - 40 sccm. Other steps are the same as those in Specific Embodiments 1 to 7.
[0040] Specific Embodiment 9: This embodiment is a dual - active - site tungsten - oxide - based electrode used as a catalyst for a Li - CO2 battery.
[0041] Specific Embodiment Ten: The difference between this embodiment and any one of Specific Embodiments One to Nine is that a Li-CO2 battery is assembled using a tungsten oxide-based electrode with dual active sites, which is specifically completed according to the following steps: Using the tungsten oxide-based electrode with dual active sites as the catalyst, lithium metal as the negative electrode, and CO2 gas as the positive electrode, assemble the Li-CO2 battery in a glove box with a water and oxygen content less than 0.01 ppm; the assembly sequence is as follows: CR2032 lithium-air hole-shaped button positive electrode case, catalyst, separator, 80 μL electrolyte, negative electrode, gasket, shrapnel, negative electrode case; after assembly, transfer the battery to a sealed container, continuously introduce CO2 gas for 15 min to 20 min to remove the air in the container, and then let the battery stand for 12 h to 14 h to ensure that CO2 and the electrolyte are fully infiltrated; the electrolyte is obtained by dissolving lithium bis(trifluoromethanesulfonyl)imide in tetraethylene glycol dimethyl ether, and the concentration of lithium bis(trifluoromethanesulfonyl)imide is 1 mol / L. Other steps are the same as those in Specific Embodiments One to Nine.
[0042] The following examples are used to verify the beneficial effects of the present invention:
[0043] Example 1: A preparation method of a tungsten oxide-based electrode (N-O v -W5O 14 ) is specifically completed according to the following steps:
[0044] I. Preparation of WO3 nanosheets:
[0045] ①. Dissolve 3.628 g of Na2WO4·2H2O in 70 mL of deionized water, dropwise add HCl solution to the solution under stirring until the pH value of the solution is 1.5, then add 1.286 g of NaCl and 1.386 g of H2C2O4, and continuously stir until completely dissolved to obtain a mixed solution;
[0046] The mass fraction of the HCl solution described in step I① is 6 mol / L;
[0047] ②. Transfer the mixed solution and the titanium substrate to a reaction kettle, perform a hydrothermal reaction at 150 °C for 16 h, cool to room temperature, and take out the sample; wash it 3 times with deionized water and anhydrous ethanol respectively, and then dry it at 60 °C for 4 h to obtain an array of WO3 nanosheets grown on the surface of the titanium substrate;
[0048] II. Preparation of O v -W5O 14 nanosheets:
[0049] Place the WO3 nanosheet array grown on the surface of the titanium substrate in a tubular furnace, purge with argon until the air in the reaction chamber is removed, stop passing argon, introduce N2 into the reaction chamber and evacuate to 60 Pa, then turn on the plasma radio frequency power supply and treat for 60 s under the conditions of a temperature of 400 °C and a power of 500 W to obtain N-O v -W5O 14 nanosheets, which are tungsten oxide-based electrodes with dual active sites;
[0050] The flow rate of N2 described in step two is 20 sccm.
[0051] Example 2: The difference between this example and Example 1 is that in step two, it is treated for 30 s under the conditions of a temperature of 400 °C and a power of 500 W to obtain O v -W5O 14 nanosheets. Other steps and parameters are the same as those in Example 1.
[0052] Example 3: The difference between this example and Example 1 is that in step two, it is treated for 90 s under the conditions of a temperature of 400 °C and a power of 500 W to obtain N-O v -W5O 14 -90 s nanosheets. Other steps and parameters are the same as those in Example 1.
[0053] Comparative Example 1: The preparation method of W5O 14 nanosheets is specifically completed according to the following steps:
[0054] I. Prepare WO3 nanosheets:
[0055] ①. Dissolve 3.628 g of Na2WO4·2H2O in 70 mL of deionized water, dropwise add HCl solution to the solution under stirring until the pH value of the solution is 1.5, then add 1.286 g of NaCl and 1.386 g of H2C2O4, and continuously stir until completely dissolved to obtain a mixed solution;
[0056] The mass fraction of the HCl solution described in step one ① is 6 mol / L;
[0057] ②. Transfer the mixed solution and the titanium substrate to a reaction kettle, carry out a hydrothermal reaction at 150 °C for 16 h, cool to room temperature, and take out the sample; wash it 3 times with deionized water and anhydrous ethanol in sequence, and then dry it at 60 °C for 4 h to obtain a WO3 nanosheet array grown on the surface of the titanium substrate;
[0058] II. Place the WO3 nanosheet array grown on the surface of the titanium substrate in a tubular furnace, and then anneal it in a nitrogen atmosphere at 400 °C for 30 min, and cool to room temperature to obtain W5O 14 nanosheets.
[0059] Figure 2 In which, a and b are SEM images of WO3 nanosheets at different magnification factors; Figure 3 In which, a and b are N-O v -W5O 14 SEM images of nanosheets;
[0060] From Figure 2 and Figure 3 it can be seen that: the surface of N-O v -W5O 14 becomes rough due to plasma etching, but the nanosheet structure remains intact. The three-dimensional framework composed of cross-linked nanosheets can provide fast ion / electron transport channels and at the same time provide space for the deposition of Li2CO3. The elemental surface distribution analysis is as Figure 4 shown;
[0061] Figure 4 is the EDX image of the N-O v -W5O 14 nanosheets prepared in the second step of Example 1;
[0062] From Figure 4 it can be seen that: in the N-O v -W5O 14 nanosheet array, nitrogen, tungsten, and oxygen elements are evenly distributed.
[0063] Figure 5 is the TEM image of the N-O v -W5O 14 nanosheets prepared in the second step of Example 1;
[0064] From Figure 5 it can be seen that: the interplanar spacing of the N-O v -W5O 14 nanosheets is 0.38 nm, corresponding to the (001) crystal plane of W5O 14 (JCPDS card no.41-0745).
[0065] Figure 6 are the XRD patterns of various samples;
[0066] From Figure 6 it can be observed that the XRD spectrum after treatment changes from the original WO3 to oxygen-deficient-rich W5O 14 , which is due to the generation of oxygen vacancies induced by high-energy plasma treatment of the samples, causing a phase change in the material. However, when the treatment time is extended to 90 s, N-O v -W5O 14A weak diffraction peak appears at 43.85° in the -90s nanosheets, corresponding to the diffraction peak of WN (JCPDS card no. 25-1257). This is because part of W5O is nitrided due to the too long processing time, and at this time, the lattice structure of W5O is damaged. Therefore, in-depth tests are carried out on W5O, O-W5O(30s), N-O-W5O(60s). In addition, the diffraction peaks at 38.42°, 40.17°, 53.00°, and 70.66° in all samples are attributed to the titanium foil substrate (JCPDS card no. 44-1294). 14 When part of W5O is nitrided, the lattice structure of W5O 14 is damaged. Therefore, for W5O 14 , O v -W5O 14 (30s), N-O v -W5O 14 (60s), in-depth tests are conducted. In addition, the diffraction peaks at 38.42°, 40.17°, 53.00°, and 70.66° in all samples are attributed to the titanium foil substrate (JCPDS card no. 44-1294).
[0067] Figure 7 are the EPR spectra of various samples;
[0068] Figure 7 Further indicates the existence of oxygen vacancies in N-O-W5O v -W5O 14 nanosheets.
[0069] Figure 8 is the structural schematic diagram of the Li-CO2 battery assembled with the catalyst;
[0070] Using the above-prepared materials as catalysts respectively, with lithium metal as the negative electrode and CO2 gas as the positive electrode, a Li-CO2 battery is assembled in a glove box with the water and oxygen content less than 0.01 ppm( Figure 8 ); The assembly sequence is as follows: CR2032 lithium-air hole-shaped button positive electrode shell, catalyst, separator, 80 μL electrolyte, negative electrode, gasket, shrapnel, negative electrode shell; After assembly, the battery is transferred to a sealed container, and CO2 gas is continuously introduced for 15 min to 20 min to remove the air in the container, and then the battery is left standing for 12 h to 14 h to ensure that CO2 and the electrolyte are fully infiltrated; The electrolyte is obtained by dissolving lithium bis(trifluoromethanesulfonyl)imide in tetraethylene glycol dimethyl ether, and the concentration of lithium bis(trifluoromethanesulfonyl)imide is 1 mol / L.
[0071] Figure 9 are the first-cycle constant current charge-discharge curves of the Li-CO2 batteries assembled with various catalysts;
[0072] Figure 10 are the time-voltage curves of the Li-CO2 batteries assembled with various catalysts;
[0073] From Figure 9 and Figure 10 it can be seen that: N-O v -W5O14 The nanosheets have the lowest overpotential (1.25 V) and a cycling stability of up to 2190 h (at a current density of 20 μA cm -2 ).
[0074] Figure 11 Figure for the rate performance curves of Li-CO2 batteries assembled with various catalysts;
[0075] From Figure 11 it can be seen that: at each current density, the N-O v -W5O 14 nanosheets have the lowest polarization overpotential. The above electrochemical performance tests show that the strategy of constructing dual active sites by dual defect engineering can effectively improve the reaction kinetics of CRR and CER and enhance the performance of Li-CO2 batteries.
Claims
1. A preparation method of a tungsten oxide-based electrode with dual active sites, characterized in that The preparation method is specifically completed according to the following steps: I. Preparation of WO3 nanosheets: ① Dissolve Na2WO4·2H2O in deionized water. Under stirring conditions, add HCl solution until the pH value of the solution is 1.
5. Then add NaCl and H2C2O4 and continue stirring until completely dissolved to obtain a mixed solution. ② Transfer the mixed solution and the titanium substrate to a reaction kettle, carry out hydrothermal reaction at 140°C - 160°C for a period of time, cool to room temperature, and take out the sample. Wash and dry the sample to obtain an array of WO3 nanosheets grown on the surface of the titanium substrate. II. Preparation of N-O v -W5O 14 nanosheets: Place the WO3 nanosheet array grown on the surface of the titanium substrate in a tube furnace, purge with argon until the air in the reaction chamber is removed, stop passing argon, introduce N2 into the reaction chamber and evacuate to 60 Pa, then turn on the plasma radio frequency power supply, and treat it for 60 s to 90 s under the conditions of a temperature of 400 °C to 500 °C and a power of 500 W to obtain N-O v -W5O 14 nanosheets, which are tungsten oxide-based electrodes with dual active sites.
2. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, characterized in that In step I①, the mass ratio of Na2WO4·2H2O to the volume of deionized water is (3g - 4g):(60mL - 80mL).
3. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, wherein In step I①, the mass ratio of NaCl to the volume of deionized water is (1g - 2g):(60mL - 80mL).
4. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, characterized in that In step I①, the mass ratio of H2C2O4 to the volume of deionized water is (1g - 2g):(60mL - 80mL).
5. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, wherein In step I①, the concentration of the HCl solution is 5mol / L - 7mol / L.
6. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, characterized in that In step I②, the titanium substrate is a titanium foil; the thickness of the titanium foil is 0.1mm; the time of the hydrothermal reaction in step I② is 14h - 18h.
7. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, characterized in that In step I②, the solid product is washed 2 - 4 times with deionized water and anhydrous ethanol in sequence; the drying temperature in step I② is 50°C - 80°C, and the drying time is 3h - 5h.
8. The preparation method of a dual-active-site tungsten oxide-based electrode according to claim 1, characterized in that In step II, the flow rate of N2 is 20sccm - 40sccm.
9. Use of a tungsten oxide-based electrode with dual active sites prepared by the preparation method according to claim 1, characterized in that A tungsten oxide-based electrode with dual active sites is used as a catalyst for a Li-CO2 battery.
10. Use of a tungsten oxide-based electrode with dual active sites according to claim 9, characterized in that Assemble a Li-CO2 battery using a tungsten oxide-based electrode with dual active sites, which is specifically completed according to the following steps: Use the tungsten oxide-based electrode with dual active sites as the catalyst, lithium metal as the negative electrode, and CO2 gas as the positive electrode to assemble a Li-CO2 battery in a glove box with a water and oxygen content less than 0.01ppm. The assembly sequence is as follows: CR2032 lithium-air hole-shaped button positive electrode shell, catalyst, separator, 80μL electrolyte, negative electrode, gasket, shrapnel, negative electrode shell. After assembly, transfer the battery to a sealed container, continuously introduce CO2 gas for 15min - 20min to remove the air in the container, and then let the battery stand for 12h - 14h to ensure that CO2 and the electrolyte are fully infiltrated. The electrolyte is obtained by dissolving lithium bis(trifluoromethanesulfonyl)imide in tetraethylene glycol dimethyl ether, and the concentration of lithium bis(trifluoromethanesulfonyl)imide is 1mol / L.