Hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide and preparation method of catalyst
阅读说明：本技术 电化学还原二氧化碳为一氧化碳的中空结构催化剂及其催化剂的制备方法 (Hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide and preparation method of catalyst ) 是由 诸海滨 陈香兰 于 2019-06-04 设计创作，主要内容包括：电化学还原二氧化碳为一氧化碳的中空结构催化剂及其制备方法。本发明属于二氧化碳资源化技术领域；在惰性氮气1000℃下碳化Cu(OH)<Sub>2</Sub>@ZIF-8复合材料,制得了中空结构的C-Cu(OH)<Sub>2</Sub>@ZIF-1000碳材料；通过调控材料的形貌来提高材料的CO<Sub>2</Sub>催化还原性能；ZIF-8的加入不仅提供了碳源和氮源,同时经过高温碳化后形成不同种类的氮,从而起到很好的催化还原作用；铜盐的加入形成了金属-氮共掺杂结构,通过两者之间的协同作用,进一步提高了材料的CO<Sub>2</Sub>催化还原能力；该方法简便、快捷、易操作、环境友好、可大规模应用于工业生产。(A hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide and a preparation method thereof. The invention belongs to the technical field of carbon dioxide recycling; carbonizing Cu (OH) at 1000 ℃ under inert nitrogen 2 @ ZIF-8 composite material, making hollow structure C-Cu (OH) 2 @ ZIF-1000 carbon material; improving CO of material by regulating and controlling morphology of material 2 Catalytic reduction performance; the addition of ZIF-8 not only provides a carbon source and a nitrogen source, but also forms different nitrogen after high-temperature carbonization, thereby playing a good role in catalytic reduction;the addition of the copper salt forms a metal-nitrogen CO-doped structure, and the CO of the material is further improved through the synergistic effect of the metal-nitrogen CO-doped structure and the copper salt 2 Catalytic reduction ability; the method is simple, convenient, fast, easy to operate, environment-friendly and applicable to industrial production in a large scale.)
1. Hollow structure catalyst for electrochemical reduction of carbon dioxide into carbon monoxide, characterized in that: the catalyst is a copper-nitrogen co-doped nano carbon material.
2. The hollow structure catalyst for electrochemically reducing carbon dioxide to carbon monoxide according to claim 1, characterized in that: the copper-nitrogen co-doped nano carbon material comprises ZIF-8 and CuCl2·2H2O, KOH, the mass ratio is: 100-300 mg: 10-20 mg: 10-20 mg.
3. A method of preparing a hollow structure catalyst for electrochemically reducing carbon dioxide to carbon monoxide as recited in claim 1, wherein: the operation steps comprise: 100-300mg of ZIF-8 is ultrasonically dispersed in 40mL of methanol solution to obtain ZIF-8 methanol solution, and 10-20mg of CuCl is added2·2H2Dissolving O in 10mL of methanol solution to obtain CuCl2·2H2O methanol solution, adding CuCl2·2H2Slowly adding the O methanol solution into the ZIF-8 methanol solution, mixing and stirring the two solutions at normal temperature for 12h to obtain CuCl2@ ZIF-8 in methanol;
the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 10-20mg of KOH in 10mL of methanol solution to obtain KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
4. The hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide and the preparation method thereof according to claims 1, 2 and 3, wherein the temperature at normal temperature is 25-30 ℃, and the methanol solution is analytically pure.
5. The hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide according to claims 1, 2 and 3 and the preparation method thereof, wherein copper in the copper-nitrogen co-doped nano carbon material catalyst accounts for 5-10% of the total molar weight of the mixture.
6. The hollow structure catalyst for electrochemically reducing carbon dioxide into carbon monoxide and the preparation method thereof according to claims 1, 2 and 3, wherein the particle size of the copper-nitrogen co-doped nano carbon material catalyst is 40-70 nm.
7. The working electrode loaded with the carbon dioxide electrochemical reduction catalyst is characterized in that the size of the working electrode is 0.5cm multiplied by 0.5cm, and the weight of the carbon dioxide electrochemical reduction catalyst loaded on the working electrode is 10-20 mg.
8. The method for preparing the working electrode loaded with the carbon dioxide electrochemical reduction catalyst as claimed in claim 7, comprising the steps of: catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000 ethanol solution in C-Cu (OH)2@ ZIF-1000 ethanol solution, adding 50 μ L of 5 wt.% Nafion solution, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
9. The method for preparing a working electrode loaded with a carbon dioxide electrochemical reduction catalyst as claimed in claim 8, wherein the solvent is deionized water or ethanol.
10. The method for preparing the working electrode loaded with the carbon dioxide electrochemical reduction catalyst according to claim 7, wherein the loading amount of the copper-nitrogen co-doped nano carbon material catalyst on the working electrode is 0.1-0.5mg/cm2。
Technical Field
The invention relates to electrochemical reduction from carbon dioxide to carbon monoxide and a preparation method thereof, in particular to a catalyst for electrochemically reducing carbon dioxide into carbon monoxide by using non-noble metal copper-based nano materials and a preparation method thereof.
Background
At present, with the continuous development of society, the combustion and utilization of fossil energy still occupy the dominant position of energy consumption, and the CO brought by the fossil energy2A series of environmental problems caused by the transitional emission seriously affect the survival and development of human society. In order to solve the above problems, excess carbon dioxide in the atmosphere is electrochemically reduced by using electric energy generated from renewable energy sources, and converted into other useful substances, thereby realizing CO2And (5) resource green conversion. Carbon dioxide is a stable compound, and CO is realized by an electrochemical method2Is an effective way, but the conversion effect is largely determined by CO2Morphology, performance and preparation method of the electro-reduction catalyst.
Much research is currently underway to electroreduce CO2The catalyst is Cu, Au, Ag, Pb, Pd, etc. The reduction products, conversion, current efficiency are different on different catalysts. Wherein, the catalyst with high selectivity to CO products mainly comprises Au, Ag, Pd and other noble metal catalysts. However, the catalysts have poor stability, low activity, lack of resources and high price, thereby influencing the electrochemical reduction of CO2Is widely applied.
In the years, non-noble metal copper nitrogen co-doped nano carbon material catalysts attract extensive attention of people. The copper-nitrogen co-doped nano carbon material catalyst has proved to have very high oxygen reduction catalytic activity. However, the application of this material in the electrochemical reduction of carbon dioxide to carbon monoxide has been relatively less studied.
Disclosure of Invention
Aiming at the problems, the invention provides a catalyst for electrochemically reducing carbon dioxide into carbon monoxide and a preparation method thereof, which utilize the copper-nitrogen co-doped nano carbon material catalyst surface copper base to have higher catalytic reduction activity, greatly reduce the over-point position in the electrochemical reduction process, increase the reduction current density, and effectively inhibit the hydrogen evolution projection accompanying the carbon dioxide reduction process.
The technical scheme of the invention is as follows: a catalyst for electrochemically reducing carbon dioxide into carbon monoxide is a copper-nitrogen co-doped nano carbon material.
The copper-nitrogen co-doped nano carbon material is obtained by mixing, stirring and synthesizing at normal temperature, wherein the synthesis raw materials comprise ZIF-8 and CuCl2.2H2O, KOH, the mass ratio of the synthetic raw materials is: 150-300 mg: 10-20 mg: 10-20 mg.
A method for preparing a catalyst for electrochemically reducing carbon dioxide to carbon monoxide comprises the following operation steps:
ultrasonic dispersing 150-300mg ZIF-8 in 40mL of methanol solution to obtain ZIF-8 methanol solution, and adding 10-20mg CuCl2.2H2Dissolving O in 10mL of methanol solution to obtain CuCl2.2H2O methanol solution, adding CuCl2.2H2Slowly adding the O methanol solution into the ZIF-8 methanol solution, mixing and stirring the two solutions at normal temperature for 12h to obtain CuCl2@ ZIF-8 in methanol;
the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 10-20mg of KOH in 10mL of methanol solution to obtain KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
Catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000 ethanol solution in C-Cu (OH)2@ ZIF-1000 ethanol solutionAdding 50 μ L of 5 wt% Nafion solution, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
In the scheme, ZIF-8 and CuCl are adopted2.2H2The molar ratio of O is 5:1-10:1, and the molar ratio of ZIF-8 to KOH is 3: 1-4: 1.
The temperature at normal temperature is 25-30 ℃, and the solvent methanol is analytically pure.
The temperature of the heat treatment is 1000 ℃, and the time of the heat treatment is 2 h.
The size of the working electrode is 0.5cm multiplied by 0.5cm, and the weight of the carbon dioxide electrochemical reduction catalyst loaded on the working electrode is 5-15 mg.
Copper in the copper-nitrogen co-doped nano carbon material catalyst accounts for 5% -10% of the total molar weight of the mixture.
The particle size of the copper-nitrogen co-doped nano carbon material catalyst is 50-60 nanometers.
In addition, the working electrode is one of carbon paper, carbon cloth, activated carbon, carbon nanofiber materials and graphene materials.
The loading capacity of the copper-nitrogen co-doped nano carbon material catalyst on the working electrode is 0.1-0.5mg cm-2。
The copper-nitrogen co-doped nano carbon material catalyst has good electrical property and stability. The method is simple in equipment, easy to control, simple in preparation of the copper-nitrogen co-doped nano carbon material and low in price.
The invention has the beneficial effects that: 1. C-Cu (OH) prepared by the invention2The @ ZIF-1000 catalyst is synthesized by a normal-temperature stirring method, and the catalyst with a nano-grade hollow structure is obtained by effectively regulating and controlling the preparation conditions of the catalyst, so that the selectivity of carbon dioxide reduction can be greatly improved, the overpotential of the carbon dioxide reduction is reduced, and the energy efficiency is improved; meanwhile, competitive hydrogen evolution side reaction in the carbon dioxide reduction process is effectively inhibited, and the electric performance and the stability are good; 2. the working electrode adopted by the invention can not only improve CO2Reduced current density and increased CO2Selectivity and conversion rate, thereby improving Faraday efficiency; the preparation method of the copper-nitrogen co-doped nano carbon material catalyst is simple, strong in forming capability, low in production cost, mature in technology, free of large amount of capital and easy in industrialization; the invention has good application prospect in the field of electrochemical reduction of carbon dioxide.
Drawings
FIG. 1 shows carbon dioxide reduction catalysts of examples 1 to 3 of the present invention in CO2Saturated 0.5M KHCO3Cyclic voltammogram of (1);
FIG. 2 shows the carbon dioxide reduction catalyst of examples 1 to 3 in the present invention in CO2Saturated 0.5M KHCO3The faradaic efficiency of CO is generated when the electrolysis is carried out for 1 hour at medium and different potentials;
FIG. 3 is a transmission electron microscope image of a carbon dioxide reduction catalyst containing a hollow structure according to example 1 of the present invention;
FIG. 4 is an XRD spectrum of the carbon dioxide reduction catalyst of examples 1 to 3 of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. According to the invention, the catalyst for electrochemically reducing carbon dioxide into carbon monoxide is a copper-nitrogen co-doped nano carbon material.
The copper-nitrogen co-doped nano carbon material is obtained by mixing, stirring and synthesizing at normal temperature, wherein the synthesis raw materials comprise ZIF-8 and CuCl2.2H2O, KOH, the mass ratio of the synthetic raw materials is: 150-300 mg: 10-20 mg: 10-20 mg.
A method for preparing a catalyst for electrochemically reducing carbon dioxide to carbon monoxide comprises the following operation steps:
ultrasonic dispersing 150-300mg ZIF-8 in 40mL of methanol solution to obtain ZIF-8 methanol solution, and adding 10-20mg CuCl2.2H2Dissolving O in 10mL of methanol solution to obtain CuCl2.2H2O methanol solution, adding CuCl2.2H2The O methanol solution was slowly added to the ZIF-8 methanol solutionMixing the two solutions at room temperature under stirring for 12 hr to obtain CuCl2@ ZIF-8 in methanol;
the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 10-20mg of KOH in 10mL of methanol solution to obtain KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
Catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000 ethanol solution in C-Cu (OH)2@ ZIF-1000 ethanol solution, adding 50 μ L of 5 wt% Nafion solution, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
In the scheme, ZIF-8 and CuCl are adopted2.2H2The molar ratio of O is 5:1-10:1, and the molar ratio of ZIF-8 to KOH is 3: 1-4: 1.
The temperature at normal temperature is 25-30 ℃, and the solvent methanol is analytically pure.
The temperature of the heat treatment is 1000 ℃, and the time of the heat treatment is 2 h.
The size of the working electrode is 0.5cm multiplied by 0.5cm, and the weight of the carbon dioxide electrochemical reduction catalyst loaded on the working electrode is 5-15 mg.
Copper in the copper-nitrogen co-doped nano carbon material catalyst accounts for 5% -10% of the total molar weight of the mixture.
The particle size of the copper-nitrogen co-doped nano carbon material catalyst is 50-60 nanometers.
The working electrode is one of carbon paper, carbon cloth, activated carbon, carbon nanofiber materials and graphene materials.
The loading capacity of the copper-nitrogen co-doped nano carbon material catalyst on the working electrode is 0.1-0.5mg cm-2。
The following is a more detailed description with reference to specific examples:
1. specific example 1:
preparing a catalyst precursor:
(1) ultrasonically dispersing 200mg of ZIF-8 in 40mL of methanol solution to obtain a ZIF-8 methanol solution, and adding 16.5mg of CuCl2.2H2Dissolving O in 10mL of methanol solution to obtain CuCl2.2H2O methanol solution, adding CuCl2.2H2Slowly adding the O methanol solution into the ZIF-8 methanol solution, mixing and stirring the two solutions at normal temperature for 12h to obtain CuCl2@ ZIF-8 in methanol;
(2) the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 12mg of KOH in 10mL of methanol solution to obtain a KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
(3) the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
(4) The catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000 ethanol solution in C-Cu (OH)2@ ZIF-1000 ethanol solution, adding 50 μ L of 5 wt% Nafion solution, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
2. Specific example 2:
preparing a catalyst precursor:
(1) ultrasonically dispersing 100mg of ZIF-8 in 40mL of methanol solution to obtain a ZIF-8 methanol solution, and adding 10mg of CuCl2.2H2Dissolving O in 10mL of methanol solution to obtain CuCl2.2H2O methanol solution, adding CuCl2.2H2Slowly adding the O methanol solution into the ZIF-8 methanol solution, mixing and stirring the two solutions at normal temperature for 12h to obtain CuCl2@ ZIF-8 in methanol;
(2) the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 10mg of KOH in 10mL of methanol solution to obtain KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
(3) the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
(4) The catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000BAlcoholic solution in C-Cu (OH)2@ ZIF-1000 ethanol solution, adding 50 μ L of 5 wt% Nafion solution, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
3. Specific example 3:
preparing a catalyst precursor:
(1) ultrasonically dispersing 300mg of ZIF-8 in 40mL of methanol solution to obtain a ZIF-8 methanol solution, and adding 20mg of CuCl2.2H2Dissolving O in 10mL of methanol solution to obtain CuCl2.2H2O methanol solution, adding CuCl2.2H2Slowly adding the O methanol solution into the ZIF-8 methanol solution, mixing and stirring the two solutions at normal temperature for 12h to obtain CuCl2@ ZIF-8 in methanol;
(2) the obtained CuCl2@ ZIF-8 methanol solution is centrifugally washed once and dried in vacuum to obtain a catalyst precursor CuCl2@ ZIF-8 composite material; adding CuCl2Continuing to ultrasonically disperse the @ ZIF-8 composite material in 40mL of methanol solution to obtain CuCl2@ ZIF-8 composite methanol solution;
dissolving another 20mg of KOH in 10mL of methanol solution to obtain KOH methanol solution, and slowly adding the obtained KOH methanol solution to CuCl2@ ZIF-8 composite material methanol solution, stirring for 12h at normal temperature to obtain Cu (OH)2@ ZIF-8 in methanol;
(3) the obtained Cu (OH)2@ ZIF-8 methanol solution is centrifugally washed for three times, dried in vacuum and activated for 1h at 200 ℃ to obtain a precursor Cu (OH)2@ ZIF-8 composite material; carbonization of the precursor Cu (OH) at 1000 ℃ under inert nitrogen2@ ZIF-8 composite material, making hollow structure C-Cu (OH)2@ ZIF-1000 nanocarbon material.
(4) The catalyst C-Cu (OH)2@ ZIF-1000 dispersed in 0.95mL ethanol solution to give C-Cu (OH)2@ ZIF-1000 ethanol solution in C-Cu (OH)2@ ZIF-1000 ethanol solution, adding 50 μ L of 5 wt% Nafion solution, and ultrasonically dispersing for 30 min; mixing the obtained mixtureCoating the composite solution on a working electrode; and naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst.
Respectively dispersing 10-20mg of the carbon dioxide electrochemical reduction catalyst in the embodiment 1-3 into 50 μ L of 5 wt% Nafion solution of 0.95mL of ethanol, and ultrasonically dispersing for 30 min; coating the resulting mixed solution on a working electrode; naturally drying the working electrode coated with the mixed solution to obtain the working electrode loaded with the carbon dioxide electrochemical reduction catalyst, wherein the loading amount is 0.1-0.5 mgcm-2。
The electrochemical performance test is carried out in an electrochemical workstation test system, a spraying catalyst is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum wire electrode is used as an auxiliary electrode to form a three-level system. The electrolyte is saturated 0.5MKHCO of carbon dioxide3An aqueous solution. The electrochemical test was performed in an electrochemical workstation test system (CHI660E. Shanghai Chenghua Co.).
The cyclic voltammetry scan curve at room temperature is shown in figure 1; FIG. 1 shows electrochemical reduction catalysts for carbon dioxide in example 1, example 2 and example 3; FIG. 1 illustrates that of the 3 catalysts, example 1 is the most catalytically active and has a greater reduction current density, i.e., C-Cu (OH)2@ ZIF-1000 catalyst; FIG. 2 shows the catalysts for electrochemical reduction of carbon dioxide in examples 1, 2 and 3; FIG. 2 illustrates the faradaic efficiency of CO production when electrolyzed at different potentials for 1 h; it can be seen from the figure that the catalyst of example 1 has the maximum CO Faraday efficiency of 90% at-0.5V, i.e., C-Cu (OH)2@ ZIF-1000 catalyst; fig. 3 is a transmission electron microscope image of the carbon dioxide reduction catalyst containing the copper-nitrogen co-doped nanocarbon material with the hollow structure in example 1, example 2, and example 3; the catalysts shown in FIG. 3 maintained the morphology of ZIF-8 for the example 2 and example 3 catalysts while the example 1 formed a hollow structure morphology; i.e., C-Cu (OH)2@ ZIF-1000 catalyst; FIG. 4 shows examples 1, 2 and 3, and it can be seen from FIG. 4 that CuCl was added2.2H2O, obtaining catalysts with different dominant crystal faces; (111) (200) (2) in catalysts of examples 1 and 220) Is the dominant crystal face simple substance copper nano particle.
The temperature at normal temperature is 25-30 ℃, and the solvent methanol is analytically pure.
The temperature of the heat treatment is 1000 ℃, and the time of the heat treatment is 2 h.
The size of the working electrode is 0.5cm multiplied by 0.5cm, and the weight of the carbon dioxide electrochemical reduction catalyst loaded on the working electrode is 10 mg.
Copper in the copper-nitrogen co-doped nano carbon material catalyst accounts for 10% of the total molar weight of the mixture.
The particle size of the copper-nitrogen co-doped nano carbon material catalyst is 50-60 nanometers.
The working electrode is one of carbon paper, carbon cloth, activated carbon, carbon nanofiber materials and graphene materials.
The loading capacity of the copper-nitrogen co-doped nano carbon material catalyst on the working electrode is 0.4mgcm-2。
C-Cu (OH) prepared by the invention2The @ ZIF-1000 catalyst is synthesized by a normal-temperature stirring method, and the catalyst with a nano-grade hollow structure is obtained by effectively regulating and controlling the preparation conditions of the catalyst, so that the selectivity of carbon dioxide reduction can be greatly improved, the overpotential of the carbon dioxide reduction is reduced, and the energy efficiency is improved; meanwhile, competitive hydrogen evolution side reaction in the carbon dioxide reduction process is effectively inhibited, and the electric performance and the stability are good; in addition, the working electrode adopted by the invention can not only improve CO2Reduced current density and increased CO2Selectivity and conversion rate, thereby improving Faraday efficiency; the preparation method of the copper-nitrogen co-doped nano carbon material catalyst is simple, strong in forming capability, low in production cost, mature in technology, free of large amount of capital and easy in industrialization; the invention has good application prospect in the field of electrochemical reduction of carbon dioxide.
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