Heterojunction two-dimensional nanosheet material and preparation method and application thereof
By preparing the heterojunction two-dimensional nanosheet material Cu2(OH)3NO3@Cu-BTC, the problem of low selectivity of multi-carbon products in Cu-based catalysts was solved, achieving efficient electroreduction of carbon dioxide and improving the stability and selectivity of multi-carbon products of the catalyst. It can be applied to electrocatalytic carbon dioxide reduction and Zn-CO2 batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-04-14
AI Technical Summary
Existing Cu-based electrocatalytic carbon dioxide reduction catalysts exhibit low selectivity for multi-carbon products and are prone to aggregation or reconstruction during electrolysis, leading to a decline in catalytic performance. There is an urgent need for highly selective catalyst materials to improve the yield of multi-carbon products.
A core-shell structure Cu2(OH)3NO3@Cu-BTC was formed by using heterojunction two-dimensional nanosheet materials, including copper hydroxynitrate nanosheets and metal-organic framework Cu-BTC, through co-precipitation reaction and epitaxial growth. Tristyric acid was used to regulate the morphology and surface activation, thereby improving the stability and selectivity of catalytic active sites.
Cu NS-BTC significantly improves the selectivity of carbon dioxide electroreduction to produce ethanol and ethylene. It exhibits high efficiency in alkaline media and good cycle stability and power density in Zn-CO2 batteries.
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Figure CN121853006A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon dioxide conversion technology, and in particular to a heterojunction two-dimensional nanosheet material, its preparation method, and its application. Background Technology
[0002] Carbon dioxide (CO2) is an abundant C1 resource. Electrocatalytic carbon dioxide reduction (eCO2RR) can convert CO2 molecules into organic compounds with higher energy density (C1). 2+ This involves storing electrical energy in the form of chemical energy. In the search for technologies to utilize CO2, eCO2RR has broad market prospects and advantages in storing intermittent renewable energy, producing high-energy-density fuels, and value-added chemicals. Combining renewable electricity with eCO2RR will help form an artificial carbon cycle closed loop, thereby accelerating the achievement of the "carbon neutrality" goal. Under normal temperature and pressure conditions, the activation of CO2 molecules and C... Precise control of the C coupling process is one of the two biggest challenges in CO2 conversion.
[0003] Copper (Cu)-based catalysts are a type of catalyst that can produce C 2+ The product's eCO2RR catalyst has attracted considerable attention in this field. According to the Sabatil principle, Cu exhibits moderate adsorption strength for CO molecules, which can be further converted to CO by C... C-coupling reduces CO to higher-value C. 2+ Products, including hydrocarbons and oxygen-containing compounds, play a crucial role in the energy and chemical industries, such as fuel additives, plastics, disinfectants, and pharmaceuticals. Two-dimensional nanomaterials possess unique structural characteristics and physicochemical properties, and compared to bulk catalysts, they generally exhibit superior catalytic activity, leading to their widespread application in industrial production. However, the structure and composition of two-dimensional nanomaterials vary, and numerous factors influence their synthesis, all of which affect their catalytic performance. Therefore, designing synthetic routes to synthesize two-dimensional nanomaterials with high catalytic activity is of great significance. Metal-organic framework materials can be used to derive catalysts with special morphologies through in-situ electrolysis. Organic molecule modification can not only regulate the microenvironment of the catalytic interface but also induce surface reconstruction, thereby increasing C... 2+ Product selectivity. For example, methanethiol molecules induce surface reconstruction of the Cu electrode, resulting in a rough Cu surface, which promotes the production of eCO2RR and C. 2+ Products, but the selectivity is still very low.
[0004] The dynamic evolution of copper-based catalysts is a double-edged sword. Aggregation or reconstruction easily occurs during eCO2RR, potentially leading to the loss of the catalyst's initial structure and active sites, resulting in a decline in eCO2RR catalytic performance. Conversely, the in-situ formation of coordinated unsaturated active sites during electrolysis can alter the binding energy of adsorption intermediates, potentially enhancing eCO2RR catalytic performance. However, research on organic molecule-induced electrochemical reconstruction in eCO2RR remains scarce, hindering the promotion of CO2 to C conversion. 2+ The reaction mechanism of the products still needs further exploration. Given the low selectivity of existing Cu-based electrocatalytic carbon dioxide reduction catalysts for multi-carbon products, there is an urgent need to find a highly selective catalyst material to achieve efficient electroreduction of carbon dioxide and improve the yield of multi-carbon products. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a heterojunction two-dimensional nanosheet material, its preparation method, and its applications. Through raw material and structural design, the obtained heterojunction two-dimensional nanosheet material effectively improves the control of C. 2+ The selectivity of the products can be used for the electroreduction of carbon dioxide to produce C. 2+ And recyclable aqueous Zn-CO2 batteries.
[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a heterojunction two-dimensional nanosheet material, comprising copper hydroxynitrate nanosheets and a metal-organic framework, wherein the metal-organic framework is epitaxially grown on the surface of the copper hydroxynitrate nanosheets. The metal-organic framework has copper ions as its metal ions and triphenyl alkanoic acid as its organic ligand.
[0007] Compared with the prior art, the heterojunction two-dimensional nanosheet material provided by the present invention has a core-shell structure. The core material, copper hydroxynitrate nanosheets (Cu2(OH)3NO3, denoted as Cu NS), and the shell material, metal-organic framework (Cu-BTC), constitute the heterojunction. Trimethylbenzene acid has a surface activation effect and can adjust the morphology of the heterojunction two-dimensional nanosheet material to form Cu2(OH)3NO3@Cu-BTC (denoted as Cu NS-BTC) with a unique structure.
[0008] In subsequent eCO2RR applications, the heterojunction two-dimensional nanosheet material Cu NS-BTC can be used to obtain a highly efficient electrocatalyst for the electroreduction of carbon dioxide, Cu-N-BTC, through in-situ electrolysis. Compared with copper-based catalysts Cu2(OH)3NO3 and Cu-BTC, it significantly improves the selectivity of carbon dioxide electroreduction to produce ethanol and ethylene.
[0009] Preferably, the copper hydroxynitrate nanosheets and the metal-organic framework have similar lattice structures.
[0010] In this invention, Cu2(OH)3NO3 and Cu-BTC have similar crystal structures, so Cu-BTC can be grown in situ on the surface of Cu2(OH)3NO3 through copper active sites to obtain Cu2(OH)3NO3@Cu-BTC with a core-shell structure.
[0011] Preferably, the thickness of the copper hydroxynitrate nanosheets is 15nm~40nm (more preferably 20nm~30nm).
[0012] Preferably, the thickness of the heterojunction two-dimensional nanosheet material is 60nm~100nm (more preferably 70nm~80nm).
[0013] Preferably, the sheet size of the heterojunction two-dimensional nanosheet material is 200nm~700nm.
[0014] In this invention, the heterojunction two-dimensional nanosheet material has an irregular sheet-like structure with a length and width in the range of 200 nm to 700 nm.
[0015] Secondly, the present invention provides a method for preparing the heterojunction two-dimensional nanosheet material, comprising the following steps: Copper nitrate, water-soluble organic amine, and water were mixed, and the resulting mixed solution was subjected to a co-precipitation reaction to obtain a solution of hydroxycopper nitrate nanosheets. A pyromellitic acid solution was added to the hydroxycopper nitrate nanosheet solution, and epitaxial growth was performed to obtain a heterojunction two-dimensional nanosheet material.
[0016] The present invention provides a method for preparing heterojunction two-dimensional nanosheet materials. Using copper nitrate and water-soluble organic amines as raw materials, hydroxylated copper nitrate nanosheets are obtained through a co-precipitation reaction. The morphology of the two-dimensional nanosheets is further adjusted using trimellitic acid. Cu-BTC is then grown in situ at copper sites to obtain Cu2(OH)3NO3@Cu-BTC with a core-shell structure. The water-soluble organic amine provides an alkaline environment, hydrolyzes to generate hydroxide ions, and reacts with copper nitrate to form Cu2(OH)3NO3. Simultaneously, the water-soluble organic amine also acts as a surfactant to regulate the morphology of the hydroxylated copper nitrate nanosheets.
[0017] Preferably, the water-soluble organic amine includes ethanolamine.
[0018] Preferably, the concentration of copper nitrate in the mixed solution is 1 mM to 10 mM, and the concentration of water-soluble organic amine is 0.05 mM to 0.5 mM.
[0019] Preferably, the temperature of the coprecipitation reaction is 10℃~40℃, and the reaction time is 12h~48h (more preferably 24h~48h).
[0020] Preferably, the concentration of the pyromellitic acid solution is 5 mM to 20 mM.
[0021] Preferably, the molar ratio of copper nitrate in the mixed solution to trimesic acid in the trimesic acid solution is (10~20):1.
[0022] Preferably, the epitaxial growth temperature is 10℃~40℃ and the growth time is 10min~60min (more preferably 20min~40min).
[0023] For example, after epitaxial growth, the process also includes washing and drying to obtain heterojunction two-dimensional nanosheet materials. Washing can be performed three times with an ethanol-water solution, followed by vacuum drying.
[0024] Thirdly, the present invention provides an application of the heterojunction two-dimensional nanosheet material described above in electrocatalytic carbon dioxide reduction.
[0025] Preferably, in the electrocatalytic carbon dioxide reduction, the working electrode comprises carbon paper loaded with the heterojunction two-dimensional nanosheet material.
[0026] More preferably, the carbon paper has a gas diffusion layer (GDL).
[0027] Fourthly, the present invention provides a cathode material, including the heterojunction two-dimensional nanosheet material described above.
[0028] Fifthly, the present invention provides a Zn-CO2 battery, comprising the heterojunction two-dimensional nanosheet material or the cathode material.
[0029] Preferably, in the Zn-CO2 battery, the cathode electrolyte includes potassium hydroxide, and the anode electrolyte includes potassium hydroxide and zinc acetate.
[0030] The present invention has the following beneficial effects: This invention utilizes anhydrous copper nitrate, ethanolamine, and trimesic acid as raw materials to prepare CuNS-BTC via a co-precipitation method. The raw materials are inexpensive and readily available, the approach is ingenious, the preparation method is simple, and the cost is low. The heterojunction two-dimensional nanosheet material CuNS-BTC exhibits good electrocatalytic reduction performance for CO2. CuNS-BTC can be used to obtain a highly efficient electrocatalyst for CO2 electroreduction, Cu-N-BTC, through in-situ electrolysis. In an alkaline medium, using a flow electrolytic cell can significantly improve the reduction of CO2. 2+ Product selectivity; Cu-N-BTC as an eCO2RR catalyst can be used to prepare cyclic charge-discharge aqueous Zn-CO2 batteries, with good cycle stability and power density.
[0031] Experimental results show that in a 1 mol / L KOH solution, the C content of the heterojunction two-dimensional nanosheet material Cu NS-BTC... 2+ The product exhibits a Faraday efficiency (FE) of 74.7% at -1.3V vs. RHE, while the corresponding C0 2+ Product partial current density (J) C2 The value is 164.3 mA / cm. 2 The heterojunction two-dimensional nanosheet material Cu NS-BTC at 42.5 mA / cm² 2 The maximum power density at the discharge current density is 21.5 mW / cm². 2 The corresponding FE C2+ A level consistently above 60% indicates that the primary process during battery discharge is the conversion of CO2 to C. 2+ Product conversion. Furthermore, charge-discharge cycle testing can be performed at 5 mA / cm². 2 The continuous operation for more than 75 hours demonstrates that the Zn-CO2 battery based on CuNS-BTC has good charge-discharge cycle stability, showcasing the great potential of CuNS-BTC in practical applications of eCO2RR. Attached Figure Description
[0032] Figure 1 This is a TEM image of Cu NS-BTC in Embodiment 1 of the present invention.
[0033] Figure 2 The images show the transmission electron microscopy (TEM) elemental analysis of Cu NS-BTC in Example 1 of this invention. Figures a through e are the HAADF and EDS elemental distribution diagrams, respectively.
[0034] Figure 3 This is a SEM image of Cu NS-BTC in Embodiment 1 of the present invention.
[0035] Figure 4 This is the XRD pattern of Cu NS-BTC in Embodiment 1 of the present invention.
[0036] Figure 5 This is a TEM image of Cu NS-BTC in Embodiment 2 of the present invention.
[0037] Figure 6 This is a TEM image of Cu NS-BTC in Embodiment 3 of the present invention.
[0038] Figure 7 This is a SEM image of the working electrode after the reaction in Application Example 1 of the present invention.
[0039] Figure 8The images shown are TEM images of the working electrode after the reaction in Application Example 1 of this invention. Figures a through h are the TEM image, HRTEM image, HAADF image, and EDS elemental distribution map, respectively.
[0040] Figure 9 This is the XRD pattern of the working electrode after reaction in Application Example 1 of the present invention.
[0041] Figure 10 This is a Faraday efficiency distribution diagram of each product at different reduction potentials in Application Example 1 of the present invention.
[0042] Figure 11 This is the Faraday efficiency of the multi-carbon products at different reduction potentials in Application Example 1 of the present invention.
[0043] Figure 12 The current density of the multi-carbon products at different reduction potentials in Application Example 1 of the present invention is shown.
[0044] Figure 13 This is a stability test of the electrolysis of carbon dioxide reduction at a potential of -1.3V for more than 12 hours in Application Example 1 of the present invention, corresponding to the current density and the Faraday efficiency of ethylene and ethanol.
[0045] Figure 14 The excitation curve and power density curve of the Zn-CO2 battery in Application Example 2 of this invention are shown.
[0046] Figure 15 The results show the selectivity of CO2 reduction products of the Zn-CO2 battery under different constant current charging voltages in Application Example 2 of this invention.
[0047] Figure 16 The results show the charge-discharge cycle stability of the Zn-CO2 battery in Application Example 2 of this invention.
[0048] Figure 17 This is a TEM image of Cu NS in Comparative Example 1 of the present invention.
[0049] Figure 18 The images show the transmission electron microscopy (TEM) elemental analysis of Cu NS in Comparative Example 1 of this invention. Figures a through e are the HAADF and EDS elemental distribution diagrams, respectively.
[0050] Figure 19 This is a SEM image of Cu NS in Comparative Example 1 of the present invention.
[0051] Figure 20 The image shows the XRD pattern of Cu NS in Comparative Example 1 of this invention.
[0052] Figure 21 This is a SEM image of the working electrode reaction in Comparative Application Example 1 of the present invention.
[0053] Figure 22 The images shown are TEM images of the working electrode after the reaction in Comparative Application Example 1 of this invention. Figures a through g are the TEM image, HR TEM image, HAADF image, and EDS elemental distribution map, respectively.
[0054] Figure 23 The image shows the XRD pattern of the working electrode after reaction in Comparative Application Example 1 of this invention.
[0055] Figure 24 This is a Faraday efficiency distribution diagram of each product at different reduction potentials in Comparative Application Example 1 of the present invention.
[0056] Figure 25 This invention provides a comparative application example 1 of the Faraday efficiency of multi-carbon products at different reduction potentials.
[0057] Figure 26 The current density of the multi-carbon products at different reduction potentials in Comparative Application Example 1 of this invention is shown. Detailed Implementation
[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0059] In this embodiment of the invention, all raw materials not specifically described can be obtained through commercial channels.
[0060] Example 1 This embodiment provides a heterojunction two-dimensional nanosheet material CuNS-BTC, comprising copper hydroxynitrate nanosheets CuNS and a metal-organic framework Cu-BTC, wherein the metal-organic framework Cu-BTC is epitaxially grown on the surface of the copper hydroxynitrate nanosheets CuNS.
[0061] The preparation method of the above-mentioned heterojunction two-dimensional nanosheet material includes the following steps: S100. 22.5 mg (0.12 mmol) of anhydrous copper nitrate and 0.002 mmol of ethanolamine were added to 30 mL of water and ultrasonically dispersed to form a mixed solution. Co-precipitation reaction was carried out at room temperature. After 48 h, a solution of copper hydroxynitrate nanosheets was obtained.
[0062] S200. Add 0.008 mmol of pyromellitic acid to water to form a 10 mM pyromellitic acid solution.
[0063] This embodiment does not limit the order of S100 and S200.
[0064] S300. Add pyromellitic acid solution to the hydroxy-copper nitrate nanosheet solution, mix evenly by ultrasonication, and perform epitaxial growth at room temperature. After 30 min, wash three times with ethanol aqueous solution, collect by centrifugation, and vacuum dry to obtain the heterojunction two-dimensional nanosheet material Cu NS-BTC.
[0065] Transmission electron microscopy, scanning electron microscopy, and X-ray diffraction analysis were performed on the Cu NS-BTC provided in this embodiment. The results are as follows: Figures 1-4 As shown. From Figures 1-3 As can be seen, Cu NS-BTC has a clear nanosheet structure, and Cu, N, and O elements are uniformly distributed on its surface. From... Figure 4 As can be seen, Cu NS-BTC contains Cu2(OH)3NO3, and Cu2(OH)3NO3 has a similar crystal structure to Cu-BTC.
[0066] Example 2 This embodiment provides a heterojunction two-dimensional nanosheet material CuNS-BTC, comprising copper hydroxynitrate nanosheets CuNS and a metal-organic framework Cu-BTC, wherein the metal-organic framework Cu-BTC is epitaxially grown on the surface of the copper hydroxynitrate nanosheets CuNS.
[0067] The preparation method of the above-mentioned heterojunction two-dimensional nanosheet material includes the following steps: S100. Anhydrous copper nitrate and ethanolamine were added to 30 mL of water and ultrasonically dispersed to form a mixed solution. The concentration of anhydrous copper nitrate in the mixed solution was 8 mM, and the concentration of ethanolamine was 0.3 mM. Then, a co-precipitation reaction was carried out at room temperature. After 30 h, a solution of hydroxycopper nitrate nanosheets was obtained.
[0068] S200. Add pyromellitic acid to water to form a 20mM pyromellitic acid solution.
[0069] This embodiment does not limit the order of S100 and S200.
[0070] S300. Add pyromellitic acid solution to the hydroxy copper nitrate nanosheet solution. The molar ratio of anhydrous copper nitrate to pyromellitic acid is 20:1. Mix thoroughly by ultrasonication and perform epitaxial growth at room temperature. After 50 min, wash three times with ethanol aqueous solution, collect by centrifugation, and vacuum dry to obtain the heterojunction two-dimensional nanosheet material Cu NS-BTC.
[0071] Transmission electron microscopy analysis was performed on the Cu NS-BTC provided in this embodiment, and the results are as follows: Figure 5 As shown.
[0072] Example 3 This embodiment provides a heterojunction two-dimensional nanosheet material CuNS-BTC, comprising copper hydroxynitrate nanosheets CuNS and a metal-organic framework Cu-BTC, wherein the metal-organic framework Cu-BTC is epitaxially grown on the surface of the copper hydroxynitrate nanosheets CuNS.
[0073] The preparation method of the above-mentioned heterojunction two-dimensional nanosheet material includes the following steps: S100. Anhydrous copper nitrate and ethanolamine were added to 30 mL of water and ultrasonically dispersed to form a mixed solution. The concentration of anhydrous copper nitrate in the mixed solution was 2 mM, and the concentration of ethanolamine was 0.05 mM. Then, a co-precipitation reaction was carried out at room temperature. After 40 h, a solution of copper hydroxynitrate nanosheets was obtained.
[0074] S200. Add pyromellitic acid to water to form a 5mM pyromellitic acid solution.
[0075] This embodiment does not limit the order of S100 and S200.
[0076] S300. Add pyromellitic acid solution to the hydroxy copper nitrate nanosheet solution. The molar ratio of anhydrous copper nitrate to pyromellitic acid is 10:1. Mix evenly by ultrasonication and perform epitaxial growth at room temperature. After 20 min, wash three times with ethanol aqueous solution, collect by centrifugation, and vacuum dry to obtain the heterojunction two-dimensional nanosheet material Cu NS-BTC.
[0077] Transmission electron microscopy analysis was performed on the Cu NS-BTC provided in this embodiment, and the results are as follows: Figure 6 As shown.
[0078] Application Example 1 This application example demonstrates the use of the heterojunction two-dimensional nanosheet material Cu NS-BTC in electrocatalytic carbon dioxide reduction.
[0079] The specific steps are as follows: Preparation of the working electrode: Carbon paper was cut into rectangular sheets (2.5cm × 1cm). The heterojunction two-dimensional nanosheet material Cu NS-BTC from Example 1 was ultrasonically dispersed in a mixed solvent, which consisted of water, isopropanol, and an ion exchange binder (Nafion perfluorosulfonic acid ion exchange resin) in a volume ratio of 4:1:0.025, resulting in a suspension with a concentration of 7.5 mg / mL. 200 µL of the suspension was dropped onto the surface of the carbon paper, forming an electrode area of 2cm × 0.5cm. After natural drying, the working electrode was obtained.
[0080] Electrolysis method: The above-mentioned carbon paper with a gas diffusion layer (GDL) loaded with Cu NS-BTC was used as the working electrode, and Hg / HgO electrode and platinum sheet were used as the reference electrode and counter electrode, respectively. A customized flow electrolytic cell (Wuhan Gaoshi Ruilian) was used, with an anion exchange membrane separating the anode and cathode chambers. The carbon dioxide reduction reaction was carried out for 30 min in 1.0 M KOH electrolyte at a potential of -1.3 V.
[0081] In this application example, the working electrode after 30 minutes of electrolytic carbon dioxide reduction reaction was analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results are as follows: Figures 7-9 As shown. From Figure 3 and Figure 7 It can be seen that during the electrocatalytic reduction of carbon dioxide, the nanosheet structure of the heterojunction two-dimensional nanosheet material CuNS-BTC gradually transforms into a nanoneedle-like structure, undergoing in-situ reconstruction. From Figures 8-9 As can be seen, after electroreduction of carbon dioxide, the heterostructure two-dimensional nanosheet material Cu NS-BTC is reduced to Cu-N-BTC.
[0082] The Faraday efficiency, current density, and stability of various products during the reduction of carbon dioxide at different reduction potentials were tested using a CHI 760D electrochemical workstation (Shanghai Chenhua). The results are shown in Table 1 and... Figures 10-13 As shown.
[0083] Table 1 Catalytic efficiency of different products in Application Example 1 (unit: %)
[0084] from Figure 10 As shown in Table 1, in 1M KOH electrolyte, the Faradaic efficiency of H2 is suppressed to 7.6%, while the Faradaic efficiency of multi-carbon products can reach 74.7%, with C2H4 having a Faradaic efficiency of 30.6% and C2H5OH having a Faradaic efficiency of 40.5%. Figures 11-12 As can be seen, Cu NS-BTC exhibits high selectivity for multi-carbon products within the potential range of -1.0V to -1.4V; at -1.4V vs. RHE potential, J C2+ It can reach 200 mA / cm 2 .from Figure 13 As can be seen, even after more than 12 hours of continuous reduction of carbon dioxide by electrolysis, the current density and the Faraday efficiency of ethylene and ethanol remain stable.
[0085] Application Example 2 This application example provides a Zn-CO2 battery. The heterojunction two-dimensional nanosheet material Cu NS-BTC from Example 1 is used as the cathode material, 1M KOH is used as the cathode electrolyte, and 6M KOH and 0.2M Zn(CH3COO)2 are used as the anode electrolyte.
[0086] This application example demonstrates charge-discharge cycle testing of a Zn-CO2 battery: the controlled current is 5mA / cm. 2 The circuit was charged for 10 minutes and then discharged for 10 minutes, alternating between the two. The initial charging cutoff voltage was 2.75V, and the discharge cutoff voltage was 1.25V. The test results are as follows: Figures 14-16 As shown.
[0087] from Figures 14-16 As can be seen from this, Cu NS-BTC at 42.5 mA / cm 2 The maximum discharge power density at the discharge current density is 21.5 mW / cm². 2 It exhibits superior battery performance; FE at different current densities during discharge. C2+ The battery capacity remains above 60% throughout the charge-discharge cycle; it can operate continuously for 75 hours during charge-discharge cycles, indicating that the Zn-CO2 battery constructed based on Cu NS-BTC has good charge-discharge cycle stability and has potential for practical applications in eCO2RR.
[0088] Comparative Example 1 This comparative example provides a two-dimensional nanosheet material Cu NS, the preparation method of which includes the following steps: A solution of copper hydroxynitrate nanosheets was prepared according to the method in Example 1. The solution was washed three times with an aqueous ethanol solution, collected by centrifugation, and dried under vacuum to obtain two-dimensional nanosheet material Cu NS.
[0089] Transmission electron microscopy, scanning electron microscopy, and X-ray diffraction analysis were performed on the Cu NS provided in this comparative example. The results are as follows: Figures 17-20 As shown. From Figures 17-19 As can be seen, Cu NS-BTC has a nanosheet structure, and Cu, N, and O elements are uniformly distributed on its surface. From Figure 4 As can be seen from this, Cu NS contains Cu2(OH)3NO3.
[0090] Comparative Application Example 1 This comparative application example provides an application of Cu NS in electrocatalytic carbon dioxide reduction. The preparation method of the working electrode and the electrolysis method are similar to those in Application Example 1, except that Cu NS-BTC is replaced with Cu NS in Comparative Example 1 when preparing the working electrode. The remaining operation steps are the same as in Application Example 1 and will not be described again.
[0091] In this comparative application example, the working electrode after 30 min of the carbon dioxide reduction electrolysis reaction was analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results are as follows: Figures 21-23 As shown. From Figure 19 and Figure 21 It can be seen that during the electrocatalytic reduction of carbon dioxide, the CuNS nanosheet structure gradually transforms into a nanoparticle structure, also undergoing in-situ reconstruction. From Figures 22-23 As can be seen, after the electroreduction of carbon dioxide, Cu2(OH)3NO3 is reduced to metallic Cu.
[0092] The Faraday efficiency and current density of each product during the reduction of carbon dioxide at different reduction potentials were tested using a CHI 760D electrochemical workstation (Shanghai Chenhua). The results are shown in Table 2 and... Figures 24-26 As shown.
[0093] Table 2 compares the catalytic efficiency of different products in Application Example 1 (unit: %)
[0094] from Figure 24 As shown in Table 2, using CuNS as the working electrode material, the highest Faradaic efficiency for multi-carbon products is only 37.9%, and the FE value is significantly lower than that of CuNS-BTC. This indicates that modifying CuNS with trimesic acid molecules can improve the selectivity of multi-carbon products. Figures 25-26 As can be seen, within the potential range of -1.0V to -1.4V, compared to Cu NS-BTC, Cu NS exhibits higher selectivity for multi-carbon products and J... C2+ The values were significantly reduced, indicating that modifying Cu NS with pyromellitic acid molecules can effectively improve its ability to electroreduce carbon dioxide to produce multi-carbon products.
[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A heterojunction two-dimensional nanosheet material, characterized in that, It includes copper hydroxynitrate nanosheets and a metal-organic framework, wherein the metal-organic framework is epitaxially grown on the surface of the copper hydroxynitrate nanosheets; The metal-organic framework uses copper ions as its metal ion and tris(II) benzoic acid as its organic ligand.
2. The heterojunction two-dimensional nanosheet material as described in claim 1, characterized in that, The copper hydroxynitrate nanosheets and metal-organic frameworks have similar lattice structures.
3. The heterojunction two-dimensional nanosheet material as described in claim 1 or 2, characterized in that, The thickness of the copper hydroxynitrate nanosheets is 15nm~40nm, and the thickness of the heterojunction two-dimensional nanosheet material is 60nm~100nm; the sheet size of the heterojunction two-dimensional nanosheet material is 200nm~700nm.
4. The method for preparing heterojunction two-dimensional nanosheet material according to any one of claims 1 to 3, characterized in that, Includes the following steps: Copper nitrate, water-soluble organic amine, and water were mixed, and the resulting mixed solution was subjected to a co-precipitation reaction to obtain a solution of hydroxycopper nitrate nanosheets. A pyromellitic acid solution was added to the hydroxycopper nitrate nanosheet solution, and epitaxial growth was performed to obtain a heterojunction two-dimensional nanosheet material.
5. The method for preparing heterojunction two-dimensional nanosheet materials as described in claim 4, characterized in that, The concentration of copper nitrate in the mixed solution is 1 mM to 10 mM, and the concentration of water-soluble organic amine is 0.05 mM to 0.5 mM; the water-soluble organic amine includes ethanolamine.
6. The method for preparing heterojunction two-dimensional nanosheet materials as described in claim 4, characterized in that, The concentration of the pyromellitic acid solution is 5mM~20mM, and the molar ratio of copper nitrate in the mixed solution to pyromellitic acid in the pyromellitic acid solution is (10~20):
1.
7. The method for preparing heterojunction two-dimensional nanosheet materials as described in claim 4, characterized in that, The temperature of the coprecipitation reaction is 10℃~40℃, and the reaction time is 12h~48h; The epitaxial growth temperature is 10℃~40℃, and the growth time is 10min~60min.
8. The application of the heterojunction two-dimensional nanosheet material according to any one of claims 1 to 3 or the heterojunction two-dimensional nanosheet material prepared by the preparation method of the heterojunction two-dimensional nanosheet material according to any one of claims 4 to 7 in electrocatalytic carbon dioxide reduction.
9. A cathode material, characterized in that, This includes the heterojunction two-dimensional nanosheet material as described in any one of claims 1 to 3, or the heterojunction two-dimensional nanosheet material prepared by the preparation method of the heterojunction two-dimensional nanosheet material as described in any one of claims 4 to 7.
10. A Zn-CO2 battery, characterized in that, It includes the heterojunction two-dimensional nanosheet material according to any one of claims 1 to 3 or the cathode material according to claim 9.