Search

Against issues of the high overpotential, low conversion efficiency, and poor product selectivity of electrochemical CO2 reduction (CO2ER), the research progress of electrocatalysts, electrolytes, and electrolytic cells were reviewed. It was found that the currently developed electrocatalysts contained metal nanoparticles, metal alloy, metal oxides, metal sulfide and single metal atoms. Their catalytic activity, selectivity and stability could be enhanced by adjusting the structure and particle size of electrocatalysts, doping additional elements or introducing structural defects. The electrolyte of CO2ER included aqueous electrolyte, ionic liquid electrolyte and organic electrolyte. At present, the aqueous electrolyte was widely applied, but its selectivity was inhibited by the side hydro- gen evolution reaction. The ionic liquid electrolyte and organic electrolyte has high solubility of CO2 and could restrain the hydrogen evolution reaction, which was considered as the main application research direction in the future. The CO2ER can be conducted in H-type cell, continuous flow cell and MEA reactors, among which MEA is one of the important technology to realize the scale application of electrochemical CO2 conversion. In the future, the reaction mechanism should be further studied, and the active sites should be probed to realize the precise control of catalytic performance and stability. Meanwhile, the novel electrolytes should be developed and the design of electrolytic cell should be modified in order to further improve the catalytic performance. [ABSTRACT FROM AUTHOR]

Using polyaniline (PANI) as the matrix and carbon source, ZnCl2 and FeCl3 as the metal sources, ZnFe2O4 spinel compounds were synthesized in situ on the surface of PANI by hydrothermal method. The ZnFe2O4/N-C catalyst was prepared after carbonization at high temperature, its structure and morphology were characterized and analyzed, and the effect of carbonization temperature on the structure and performance of the catalyst was investigated. The results showed that the N-C in the catalyst ZnFe2O4/N-C mainly existed in the form of amorphous carbon. The ZnFe2O4 particles were highly dispersed on the N-C surface, and with the increase of the carbonization temperature, the crystallinity of ZnFe2O4 gradually increased; the introduction of ZnFe2O4 was beneficial to the catalyst ZnFe2O4/N-C graphitization degree, when re(Fe) : n(Zn) = 2 : 1, the total concentration of metal ions was 0.1 mol/L, and the carbonization temperature was 800 °C, the ID/G (the peak D-to-G peak ratio) value of the obtained catalyst ZnFe2O4/N-C-800 was 0.97, which was lower than the ID/IG value of N-C (1.12), and it had good catalytic performance for both hydrogen evolution and oxygen evolution reactions of electrolyzed water. [ABSTRACT FROM AUTHOR]

Using aniline as monomer, ammonium persulfate as initiator, ZnCl2 and FeCl3 as metal sources, ZnFe-PANI catalyst precursor was prepared by one-step in-situ chemical polymerization method, and then ZnFe-N-C catalyst was synthesized by high temperature pyrolysis-acidification-secondary pyrolysis. The morphology and structure of the catalyst were characterized by XRD, SEM, Raman and other methods, and its catalytic performance was investigated by the electroreduction reaction of CO2. The results showed that metal doping had little effect on the morphology and structure of N-C materials, but enhanced its structural stability, increased the number of defect sites and active sites, and the area of electrochemical activity, which was conducive to the improvement of reaction performance; When the molar ratio of Zn and Fe was 3 : 1 in the precursor, the obtained sample ZnFe-N-C-3-1 had the best catalytic performance. At an overvoltage of 0.5V, the Faraday efficiency of the CO2 product by electroreduction was as high as 55 %. [ABSTRACT FROM AUTHOR]

Using aniline as monomer, ammonium persulfate as initiator, ZnCl2 and FeCl3 as metal sources, ZnFe-PANI catalyst precursor was prepared by one-step in-situ chemical polymerization method, and then ZnFe-N-C catalyst was synthesized by high temperature pyrolysis-acidification-secondary pyrolysis. The morphology and structure of the catalyst were characterized by XRD, SEM, Raman and other methods, and its catalytic performance was investigated by the electroreduction reaction of CO2. The results showed that metal doping had little effect on the morphology and structure of N-C materials, but enhanced its structural stability, increased the number of defect sites and active sites, and the area of electrochemical activity, which was conducive to the improvement of reaction performance; When the molar ratio of Zn and Fe was 3 : 1 in the precursor, the obtained sample ZnFe-N-C-3-1 had the best catalytic performance. At an overvoltage of 0.5V, the Faraday efficiency of the CO2 product by electroreduction was as high as 55 %. [ABSTRACT FROM AUTHOR]