An oxidation layer-protected copper-based catalyst, a preparation method and application thereof

Abstract

The application discloses a copper-based catalyst protected by an oxide layer and a preparation method and application thereof. y -Cu2O / Cu, MO y The copper-based catalyst is a transition metal oxide nanocluster containing oxygen defects, the Cu is a copper nanoparticle base, the MO y is coated and dispersed on the Cu base, the Cu2O is distributed at a Cu nanoparticle heterojunction, and the MO y is an oxide of any one of Zn, Ga, Zr and In transition metals with oxygen defects. y In the application, the MO y cluster is dispersed on a Cu-Cu + heterogeneous base, an atmosphere-induced method is used to form a heterogeneous structure of Cu sites in different coordination states, and the problem of CO2 activation is effectively solved, the synergistic effect of Cu and Cu + sites enhances the generation efficiency of the CO2 electro-reduction reaction, accelerates proton-electron coupling transfer kinetics, promotes C-C coupling, can realize a high current density at a lower overpotential, and the Faraday efficiency of multi-carbon product generation can reach more than 80%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon resource recycling, and particularly relates to an oxidation layer protected copper-based catalyst and a preparation method and application thereof. BACKGROUND

[0002] With the intensification of global climate change and energy crisis, reducing carbon dioxide (CO2) emissions and developing renewable energy have become important directions of current scientific research. CO2 electroreduction reaction (CO2RR) is a method of converting CO2 into valuable chemicals or fuels through electrochemical means, which has the potential to reduce CO2 emissions and achieve carbon resource recycling. However, the existing catalysts still have many challenges in selectivity, multi-carbon product generation efficiency and stability.

[0003] Copper-based catalysts have attracted much attention due to their excellent performance in multi-carbon product generation, mainly because copper sites can effectively promote C-C coupling reactions to generate multi-carbon products. However, traditional copper catalysts are prone to morphology changes during the reaction, leading to a decline in catalytic performance. In addition, carbonates and other intermediates are easily formed on the copper surface, hindering the reaction.

[0004] Oxidation state is defined as "the degree of atomic oxidation based on electron counting". Determining the oxidation state can reveal the chemical state of the element and rationalize the design of electrocatalysts. By adjusting the oxidation state, the number of valence electrons can be changed, thereby changing the electron distribution. For transition metal atoms, adjusting the oxidation state can change the arrangement of empty d orbitals and unpaired d electrons, which is crucial for the transfer of electrons to the reactants.

[0005] In recent years, researchers have found (Nat Catal 2, 709-717 (2019) Nat Commun 15, 7820 (2024)) that introducing monovalent copper (Cu + ) sites into copper catalysts can significantly improve catalytic performance. Cu + sites have unique electronic structures that help to adsorb and activate intermediates, thereby promoting C-C coupling. In particular, Cu + and Cu + composite active sites can synergize, Cu + sites help to couple CO intermediates, while Cu sites help to further hydrogenation reactions, thereby improving the selectivity and generation efficiency of multi-carbon products.

[0006] CN 111821985 A discloses a copper-based catalyst with a specific surface area of 200-350 square meters per gram, an average pore size of 5-15 nanometers, and at least a copper-containing mixture and a carrier. In the copper-containing mixture, the valence state of copper is positive one and positive two, and the carrier consisting of at least the silicon oxide, the zirconium oxide, the yttrium oxide, the germanium oxide, the magnesium oxide and the graphite fiber provides a suitable surface acidity and alkalinity to increase the interaction of copper species in the copper-containing mixture with the carrier, which is beneficial to the high dispersion of the copper-containing mixture in the carrier to improve the raw material conversion rate and product selectivity in the dimethyl oxalate hydrogenation reaction process, and also beneficial to the service life of the copper-based catalyst to facilitate large-scale industrial production.

[0007] CN112899709A discloses a copper-based compound / copper nano electrode with interface synergistic effect and its preparation method and application. The electrode includes a conductive substrate and a copper-based compound / copper nano catalyst loaded on the surface; the copper-based compound includes but is not limited to cuprous oxide, copper nitride, copper oxide and the like. The electrode material with interface regulation function utilizes the synergistic effect of monovalent copper / zero-valent copper, divalent copper / zero-valent copper and divalent copper / monovalent copper / zero-valent copper, reduces the reaction energy barrier of carbon monoxide dimerization, and thus can well inhibit the hydrogen evolution reaction during electrochemical reduction of carbon dioxide, and has good selectivity for multi-carbon products ethylene, ethanol and isopropanol.

[0008] However, the preparation method of the catalyst in the above-mentioned technology is complex, and needs to accurately control conditions such as temperature, time, pH value and concentration, which increases the cost; and the Faraday efficiency of the multi-carbon product may still have room for improvement. At the same time, Cu + The kinetic behavior of the site in the process of electro-reduction is complex and easy to be reduced, which leads to the decrease of the reaction performance; therefore, the catalyst with higher selectivity of multi-carbon product, higher catalytic efficiency and stronger stability will have broad application prospect. SUMMARY

[0009] The present application aims at the problems of low selectivity, low production efficiency of multi-carbon product and insufficient stability of the copper-based catalyst in CO2RR, and provides a copper-based catalyst protected by an oxidation layer, introduces transition metal oxide to protect the heterojunction interface, realizes efficient conversion of CO2 into multi-carbon product, and improves the stability of the catalyst structure.

[0010] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0011] A copper-based catalyst protected by an oxidation layer, wherein the structure of the copper-based catalyst represents MO x -Cu2O / Cu, MO yCu is copper nanoparticle substrate, MO x Cu2O is distributed on MO y and Cu nanoparticle hetero-interface;

[0012] The MO y is an oxide of any one of Zn, Ga, Zr, In transition metal with oxygen defects; the copper element in the copper-based catalyst accounts for more than 50wt% of the total molar amount of metal elements.

[0013] In view of the fact that Cu sites with different coordination environments are still the main active sites for C-C coupling, the catalyst structure is designed as MO y -Cu2O / Cu (reverse structure), MO y The clusters are dispersed on the hetero Cu-Cu + substrate. On this basis, the reverse Cu-oxide interface is reconstructed, which can further adjust the adsorption energy of specific intermediates by providing new degrees of freedom, thereby adjusting the product distribution. The metal oxide with rich Lewis acid sites can promote the activation of CO2 molecules, and the Cu-oxide interface boundary exhibits different CO* adsorption strengths and reaction energy barriers for C-C coupling, thereby improving the selectivity of specific multi-carbon products. The protection of the oxidation layer can further stabilize the Cu + site, prolong the service life of the catalyst, and improve the long-term stability of the catalyst. The catalyst not only exhibits excellent catalytic performance under laboratory conditions, but also has good stability, showing broad application prospects.

[0014] The molar content of Cu 0 in the copper element in the copper-based catalyst is 10%-80%, and the molar content of Cu + is 10%-80%. The oxide is highly dispersed on Cu as a small amount of component; when the content of Cu is low, it will be difficult to achieve high dispersion of the oxide, and the interface abundance will also decrease. However, it is not the more the better, and preferably, the molar content of Cu + is 5-50%.

[0015] The particle size of the copper nanoparticles in the copper-based catalyst is below 100 nm, and the MO y particle size of the nanoparticles is below 50 nm.

[0016] The present application also provides a preparation method of the oxidation layer protected copper-based catalyst, comprising the following steps:

[0017] Step 1, mix copper nanoparticles and transition metal ligands, then calcine and reduce by hydrogen to obtain MO y / Cu powder;

[0018] Step 2, MO y The copper-based catalyst MO is obtained by inducing reaction of the copper nanoparticle and the transition metal complex in an alcohol vapor environment x -Cu2O / Cu.

[0019] In the present application, the copper nanoparticle and the transition metal complex are mixed, once calcined, reduced by hydrogen, and then induced by alcohol vapor atmosphere to obtain the reverse phase catalyst, which has simple and green preparation method and mild conditions.

[0020] The copper nanoparticle can be self-made or purchased, and the self-making process comprises: fully mixing a copper precursor and a dispersing agent in a solvent, slowly adding a reducing agent, and then washing, drying and obtaining;

[0021] The copper precursor is an organic or inorganic salt of copper; preferably, the copper precursor comprises one or more of copper acetate, copper nitrate, copper oxalate, copper halide or copper carbonate;

[0022] The dispersing agent comprises one or more of common organic and inorganic dispersing agents such as ethanol, methanol and water; the reducing agent comprises one or more of ascorbic acid, sodium borohydride or potassium borohydride; and a stabilizer such as one or more of polyethylene glycol, sodium citrate and polyvinylpyrrolidone can also be added during the reaction process.

[0023] The transition metal complex comprises one or more of bis(2,2'-bipyridine)zinc(II)oxalate, bis(2,2'-bipyridine)zinc(II)acetate, bis(bipyridine)gallium(III)acetate, bis(bipyridine)gallium(III)oxalate, bis(bipyridine)zirconium(IV)acetate, bis(bipyridine)zirconium(IV)oxalate or bis(bipyridine)zirconium(IV)acetate.

[0024] The transition metal complex can be purchased or self-made, and the self-making process comprises: fully mixing a transition metal precursor and a dispersing agent at room temperature, fully mixing a required polydentate ligand and a dispersing agent, slowly adding a precursor solution, fully reacting, washing, drying and calcining;

[0025] The transition metal precursor comprises an oxide, an organic salt or an inorganic salt of a transition metal; such as zinc oxide, zinc acetate, zinc nitrate, zinc carbonate, zinc chloride, gallium oxide, gallium nitrate, gallium carbonate, gallium acetate, gallium chloride, zirconium oxide, zirconium acetate, zirconium nitrate, zirconium chloride, indium oxide, indium nitrate, indium chloride and the like;

[0026] The dispersing agent comprises one or more of common organic and inorganic dispersing agents such as ethanol, methanol and water;

[0027] The polydentate ligand comprises a compound having any one of the structures of bipyridine, oxalate, acetate and citrate;

[0028] The particle size of the copper nanoparticles and the transition metal coordination particles is below 2 microns;

[0029] The molar ratio of copper element to transition metal element is 2:1-10:1 when the copper nanoparticles and the transition metal coordination particles are mixed in step 1, preferably, the molar ratio of copper element to transition metal element is 5:1-10:1;

[0030] The mixing includes one or more of a combination of mechanical mixing, impregnation or co-precipitation. The mixing promotes the dispersion of the two elements and creates oxygen vacancies in the interface between the two phases, which is more conducive to subsequent reactions.

[0031] Preferably, the mixing is performed by ball milling for 1-6 hours, which is more conducive to the creation of oxygen vacancies.

[0032] The calcination temperature is 100-400°C, and the calcination time is 1-20 hours. The removal of organic and inorganic impurities is ensured, and the interaction between Cu and transition metal oxides is ensured. Preferably, the calcination temperature is 200-400°C, and the calcination time is 2-6 hours;

[0033] The reaction temperature of the hydrogen reduction is 100-400°C, and the reaction time is 1-20 hours. Preferably, the hydrogen reduction reaction is performed at 200-400°C for 1-3 hours;

[0034] The alcohol vapor includes one or more of a mixture of methanol, ethanol, n-propanol, isopropanol, n-butanol; preferably, the alcohol vapor is ethanol vapor

[0035] The induction reaction temperature is 100-400°C, and the reaction time is 1-20 hours. The sufficient interaction with the continuous Cu surface is ensured, and the material structure is not damaged at a too low temperature and a too high reduction temperature. Preferably, the induction reaction is performed at 200-400°C for 1-4 hours.

[0036] The application also provides the use of the copper-based catalyst protected by the oxide layer in a carbon dioxide reduction reaction.

[0037] The catalyst obtained by the application can be coated on a large-surface conductive material, including but not limited to one or more of a combination of carbon paper, carbon cloth, glassy carbon electrode, etc. Under the electrocatalytic conditions of a reaction potential of-0.6V to-2.5V (relative to a mercury / mercury oxide reference electrode) and an electrolyte including but not limited to KOH, KHCO3, NaOH, NaHCO3, etc., commonly used electrolytes, the catalyst can promote the reduction of carbon dioxide to carbon monoxide, formic acid, ethylene, ethanol, acetic acid, etc.

[0038] The Faraday efficiency of the multi-carbon product is above 50% under the electrocatalysis of the copper-based catalyst; the multi-carbon product includes one or more of acetic acid, ethylene, ethanol, and isopropanol.

[0039] Preferably, the total Faraday efficiency of the multi-carbon product is above 80%; in particular, the Faraday efficiency of the multi-carbon product is above 80% at a current density of 300 mA cm -2 The Faraday efficiency of the ethanol can be above 70%.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] (1) The present application uses an atmosphere-induced method to form a heterogeneous structure of Cu sites in different coordination states, effectively solving the problem of CO2 activation, and the synergistic effect of Cu and Cu + sites enhances the generation efficiency of the CO2 electro-reduction reaction, accelerates the proton-electron coupling kinetics, promotes C-C coupling, and can achieve a high current density at a lower overpotential, with a Faraday efficiency of the multi-carbon product of above 80%.

[0042] (2) The introduced oxide protective layer effectively stabilizes Cu + species under electro-reduction conditions, so that the catalyst prepared by the present application exhibits good stability under reaction conditions and can maintain high activity for a long time without significant performance degradation. The catalyst preparation process is simple, easy to operate, and the raw materials are simple and easy to obtain, which has industrial application potential and is suitable for popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 TEM image (a) and EDX mapping (b) of the X-ray diffraction spectrum of the ZnO 1-x -Cu2O / Cu prepared in Example 1.

[0044] Figure 2 TEM image (a) and EDX mapping (b) of the X-ray diffraction spectrum of the ZnO 1-x -Cu2O / Cu prepared in Example 1.

[0045] Figure 3 TEM image (a) and EDX mapping (b) of the X-ray diffraction spectrum of the ZnO 1-x -Cu2O / Cu prepared in Example 1.

[0046] Figure 4 Performance chart of the copper-based catalyst with an oxide layer protection prepared in the example in the application example for catalyzing CO2 electro-reduction to prepare multi-carbon products.

[0047] Figure 5 Stability test chart of the copper-based catalyst with an oxide layer protection prepared in the example in the application example for catalyzing CO2 electro-reduction to prepare multi-carbon products.

[0048] Figure 6 A performance comparison chart of the oxidation layer protected copper-based catalysts for the application example and comparative examples for catalyzing CO2 electroreduction to prepare multi-carbon products. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. Those skilled in the art can make modifications or equivalent replacements based on the technical solutions of the present application without departing from the spirit and scope of the present application, which should be covered within the protection scope of the present application.

[0050] The raw materials used in the following specific embodiments are all purchased from the market. The transition metal oxides containing oxygen defects are represented as corresponding atomic number-x, x refers to the amount of oxygen defects, such as MO y ZnO when it is the oxide of zinc 1-x Ga2O when it is the oxide of gallium 3-x .

[0051] Example 1 Oxidation layer protected copper-based ZnO 1-x -Cu2O / Cu catalyst

[0052] (1) 500 mg of anhydrous copper acetate and 2 g of PVP polyvinylpyrrolidone were dispersed in 50 mL of ethanol under the condition of a constant temperature water bath at 60°C. 1600 mg of ascorbic acid was prepared into a 80 mL solution and gradually added to the above solution, and continued to be stirred in a constant temperature water bath at 60°C for 1 hour. The obtained orange red solution was centrifuged and oven dried overnight to obtain Cu nanoparticle solid powder with a particle size of 50 nm;

[0053] (2) 476 mg of Zn(NO3)2·6H2O was ultrasonically dispersed in 20 mL of deionized water; 250 mg of 2,2'-bipyridine was ultrasonically dispersed in 10 mL of methanol; 101 mg of oxalic acid was ultrasonically dispersed in 10 mL of deionized water; then, the latter two solutions were added to the zinc nitrate solution under stirring, and continued to be stirred at room temperature for 1 hour. The obtained white solution was centrifuged and oven dried overnight to obtain a solid powder, which was recorded as bis(bipyridine)bis(oxalate)zinc(II) ZnBO with a particle size of 20 nm;

[0054] (3) The above solid powder was added to a ball mill jar at a Cu:Zn molar ratio of 8:2, and a certain amount of ZrO2 grinding balls were added to it, with a ball-to-powder ratio of 15:1. The mixture was ground at 870 rpm for 4 hours using a planetary ball mill. The resulting solid was then calcined in a muffle furnace at 400°C for 4 hours.

[0055] (4) The calcined solid powder was removed and reduced at 300°C for 1 hour in an H2 atmosphere to obtain ZnO. 1-x Cu powder is then passed through it with ethanol vapor at a flow rate of 30 ml / min, and induced at 300 °C for 1 h to obtain a catalyst for the copper-cuprous oxide heterointerface, denoted as ZnO. 1-x -Cu2O / Cu.

[0056] Figure 1 The copper-based catalyst ZnO with oxide layer protection prepared 1-x X-ray diffraction pattern of Cu₂O / Cu. Figure 1 As can be seen, Cu is present on the catalyst. 0 and Cu + Its crystal structure.

[0057] Figure 2 The copper-based catalyst ZnO with oxide layer protection prepared 1-x TEM image (a) and EDX mapping image (b) of the X-ray diffraction pattern of Cu₂O / Cu. Figure 2 As can be seen, ZnO 1-x The particles are uniformly distributed on Cu, with a size of 1-5 nm, while the Cu size is 10-30 nm. + Distributed in Cu-ZnO 1-x On the interface.

[0058] Figure 3 The copper-based catalyst ZnO with oxide layer protection prepared 1-x XPS plot of Cu₂O / Cu. (From...) Figure 3 As can be seen, the prepared catalyst contains abundant Cu. 0 and Cu + Species.

[0059] Example 2-3

[0060] Following the preparation process of Example 1, the type of alcohol vapor in step 4 was changed to methanol and n-propanol to obtain an oxide-protected copper-based catalyst, denoted as M-ZnO. 1-x -Cu₂O / Cu, P-ZnO 1-x -Cu2O / Cu.

[0061] Examples 4-6

[0062] The preparation process of Example 1 was followed, and the time for the ethanol atmosphere induced reduction reaction in step 4 was changed to 0.5 h, 2 h, and 4 h, to obtain an oxidation layer protected copper-based catalyst.

[0063] Example 7

[0064] (1) 500 mg of anhydrous copper acetate and 2 g of PVP polyvinylpyrrolidone were dispersed in 50 mL of ethanol under the condition of a constant temperature water bath at 60°C, and stirred. 1600 mg of ascorbic acid was dissolved in 80 mL of solution and gradually added dropwise to the above solution, and stirring was continued in the constant temperature water bath at 60°C for 1 hour. The obtained orange-red solution was centrifuged and oven dried overnight to obtain a Cu nanoparticle solid powder with a particle size of 50 nm;

[0065] (2) 282 mg of GaCl3 was ultrasonically dispersed in 20 mL of deionized water; 250 mg of 2,2'-bipyridine was ultrasonically dispersed in 10 mL of methanol; 101 mg of oxalic acid was ultrasonically dispersed in 10 mL of deionized water; then, the latter two solutions were added to the gallium chloride solution under stirring, and stirring was continued at room temperature for 1 hour. The obtained white solution was centrifuged and oven dried overnight to obtain a solid powder of bis(bipyridine)bis(oxalate)gallium(III);

[0066] (3) The above solid powder was added to a ball mill tank according to a Cu:Zn molar ratio of 8:2, and a certain amount of ZrO2 grinding balls were added to the tank, with a ball-to-material ratio of 15:1. A planetary ball mill was used for grinding at a speed of 870 rpm for 4 h, and the obtained solid was taken out and calcined in a muffle furnace at 400°C for 4 h.

[0067] (4) The calcined solid powder was taken out and reduced in a H2 atmosphere at 300°C for 1 h to obtain Ga2O 3-x / Cu powder, and ethanol vapor was introduced into the powder, and the induction was carried out at 300°C for 1 h to obtain a gallium oxide protected copper and cuprous oxide heterojunction catalyst, denoted as Ga2O 3-x -Cu2O / Cu.

[0068] Comparative Example 1

[0069] According to the preparation process of Example 1, the alcohol atmosphere induction step was not performed, and ZnO 1-x / Cu powder was directly obtained in step 4.

[0070] Comparative Example 2

[0071] According to the preparation process of Example 1, the Cu nanoparticles added in step 3 were replaced by Cu2O nanopowder with a particle size of about 50 nm, to obtain the corresponding catalyst ZnO 1-x / Cu2O.

[0072] Comparative Example 3

[0073] According to the preparation process of Example 1, the solid powder added in Step 3 is replaced by Cu:Zn molar ratio of 4:6 in the ball mill tank, and the subsequent steps are consistent with Example 1 to prepare the corresponding catalyst.

[0074] Application Example

[0075] The catalysts prepared in Examples 1-7 and Comparative Examples 1-3 were evaluated for their electrocatalytic CO2 reduction performance. The catalysts were coated on the surface of a gas diffusion electrode to form a working electrode, an iridium titanium plated plate was used as a counter electrode, and a Hg / HgO electrode was used as a reference electrode. The reaction was carried out in a flow electrolysis cell.

[0076] Reaction conditions: The working electrode was prepared by dispersing 10 mg of catalyst in 670 μL of water and 30 μL of Nafion solution (5 wt%) and then ultrasonically treating for 30 minutes to obtain a uniform slurry. The mixture was dropped onto the gas diffusion layer to achieve a catalyst loading of 1 mg cm -2 A peristaltic pump was used to circulate the electrolyte (0.1 M KOH) at a flow rate of 10 mL min -1 Before testing, high-purity CO2 was introduced into the flow cell at a rate of 15 mL min -1 The reaction time was controlled at each potential, and the relevant products were quantified by gas chromatography and nuclear magnetic resonance analysis. The carbon monoxide products mainly included CO and HCOOH, and the multi-carbon products mainly included C2H5OH, C2H4 and CH3COOH.

[0077] Figure 4 The performance chart of the Example 1 prepared oxide layer protected copper-based catalyst catalyzing CO2 electroreduction to prepare multi-carbon products. It can be seen from Figure 4 that the catalysts all exhibit excellent performance in the entire working range, and reach the optimum at 0.9 V vs. RHE.

[0078] Figure 5 The stability test chart of the Example 1 oxide layer protected copper-based catalyst catalyzing CO2 electroreduction to prepare multi-carbon products. The stability test was carried out in the same electrolyte and gas-liquid flow rate as the conventional test in the flow cell, and -0.9 V vs. RHE was selected as the fixed reaction potential, and the liquid phase products were analyzed every 1-3 hours. It can be seen from Figure 5 that after more than 200 hours of operation, the performance of the catalyst does not decrease significantly, showing good stability.

[0079] The carbon monoxide product and multi-carbon product faradaic efficiency of the catalysts of the examples and comparative examples are shown in Table 1 and Figure 6As shown, embodiments 1-6 all form a heterogeneous interface of copper and cuprous oxide, and at the same time form an inverse loading with transition metal oxides. Through the synergistic effect of Cu and Cu sites and the interface structure and optimization, the selectivity and efficiency of CO2 electroreduction to generate multi-carbon products are improved.

[0080] The comparison between embodiments 1-3 shows that different atmospheres induce different effects on Cu + under the same conditions, and the ethanol vapor shows the best induction effect. This indicates that the number and dispersion of Cu + species formed at this time are more conducive to multi-step proton-electron coupling transfer and corresponding C-C coupling.

[0081] The comparison between embodiments 1, 4, 5, and 6 shows that the length of the ethanol atmosphere induction time is not the longer the better. In fact, as the treatment time increases, the relative advantage of the dominant product in the multi-carbon product decreases after an initial increase. In embodiment 7, the change of the transition metal oxide has an important influence on the overall structure of the catalyst, especially the dynamic change of Cu + species during the reaction. The content of Cu + species is also not the higher the better. It can be inferred that the adsorption ability of ethanol at different interfaces and the ability to induce electron transfer have certain differences.

[0082] Comparative examples 1 and 2 both fail to form a heterogeneous interface of copper and cuprous oxide, indicating that the Cu site in a single coordination environment has limited promoting effect on C-C coupling.

[0083] Comparative example 3 has a low Cu content, and the oxide becomes the main component, which fails to achieve high dispersion and has a relatively low interface abundance. Only less than 6% Cu + species is generated after alcohol treatment. Due to the increase in the proportion of oxides, the electrical conductivity decreases significantly, and the overall performance is poor.

[0084] Comparative example 4 uses a co-precipitation method for loading, and the binding strength of the two components is relatively weak. The interface abundance, especially the defect abundance at the interface, is low. Cu + species is not induced after alcohol treatment, and the overall performance is also poor due to the poor dispersion of oxides.

[0085] Table 1 Faraday efficiency of carbon monomer products and multi-carbon products of catalysts of embodiments and comparative examples

[0086]

Claims

1. An oxidation layer-protected copper-based catalyst, characterized by, The copper-based catalyst structure represents MO y -Cu2O / Cu, MO y are transition metal oxide nanoclusters containing oxygen defects, Cu is a copper nanoparticle substrate, MO y are dispersed on the Cu substrate in a coating manner, Cu2O is distributed on MO y and Cu nanoparticle heterointerfaces; The MO y is an oxide of any one of transition metals of Zn, Ga, Zr, In with oxygen defects; the copper element in the copper-based catalyst accounts for more than 50% of the total molar amount of metal elements; The method for preparing the oxidation layer-protected copper-based catalyst comprises the steps of: Step 1, after mixing copper nanoparticles and transition metal ligands, roasting, and then hydrogen reduction to obtain MO y / Cu powder; the roasting temperature is 100-400 ℃, and the roasting time is 1-20 h; The reaction temperature of the hydrogen reduction is 100-400 DEG C, and the reaction time is 1-20 h; Step 2, the MO y The copper-based catalyst MO is obtained by inducing reaction of the Cu powder in an alcohol vapor environment y -Cu2O / Cu; the inducing reaction temperature is 100-400 ℃, and the reaction time is 1-20 h.

2. The oxidation layer-protected copper-based catalyst according to claim 1, characterized by Cu in the copper element in the copper-based catalyst 0 molar content of 10-80%, Cu + molar content of 10-80%.

3. The oxidation layer-protected copper-based catalyst according to claim 1, characterized by The particle size of the copper nanoparticles in the copper-based catalyst is below 100 nm, MO y The particle size of the nanoparticles is below 50 nm.

4. The process for the preparation of an oxidation layer-protected copper-based catalyst according to any one of claims 1 to 3, characterized in that The method for preparing the oxidation layer-protected copper-based catalyst comprises the steps of: Step 1, after mixing copper nanoparticles and transition metal ligands, roasting, and then hydrogen reduction to obtain MO y / Cu powder; the roasting temperature is 100-400 ℃, and the roasting time is 1-20 h; The reaction temperature of the hydrogen reduction is 100-400 DEG C, and the reaction time is 1-20 h; Step 2, the MO y The copper-based catalyst MO is obtained by inducing reaction of the Cu powder in an alcohol vapor environment y -Cu2O / Cu; the inducing reaction temperature is 100-400 ℃, and the reaction time is 1-20 h.

5. The method for preparing an oxidation layer-protected copper-based catalyst according to claim 4, characterized by, The molar ratio of copper element to transition metal element is 2:1-10:1 when the copper nanoparticles and the transition metal complex particles are mixed in step 1; The transition metal complex includes one or more of bis(2,2'-bipyridine)bis(oxalate)zinc(II), bis(2,2'-bipyridine)bis(acetate)zinc(II), bis(bipyridine)bis(acetate)gallium(III), bis(bipyridine)bis(oxalate)gallium(III), bis(bipyridine)bis(citrate)zirconium(IV) or bis(bipyridine)bis(oxalate)zirconium(IV).

6. The method for preparing an oxidation layer-protected copper-based catalyst according to claim 4, characterized by, The particle size of the copper nanoparticles and the transition metal complex particles is below 2 microns; The mixing includes one or more of a combination of mechanical mixing, impregnation or co-precipitation.

7. The method of claim 4, wherein the oxidic layer-protected copper-based catalyst is prepared by the steps of: The alcohol steam includes one or more of a mixture of steam of methanol, ethanol, n-propanol, isopropanol and n-butanol.

8. The oxidation layer-protected copper-based catalyst according to any one of claims 1-3 is applied in a carbon dioxide reduction reaction.

9. Use of the oxidation layer-protected copper-based catalyst according to claim 7 in a carbon dioxide reduction reaction, characterized in that, Under the electrocatalysis of the copper-based catalyst, the Faraday efficiency of the multi-carbon product is above 50%; the multi-carbon product includes one or more of acetic acid, ethylene, ethanol and isopropanol.

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