New Progress in the Study of Efficient Electrocatalytic Reduction of Carbon Dioxide

Recently, the State Key Laboratory of Catalysis of Dalian Institute of Chemical Physics, Chinese Academy of Sciences Bao Xinhe and Wang Guoxiong team made new progress in the research of high-efficiency electrocatalytic reduction of carbon dioxide. Related results have been published on Energy Environ.Sci.

Carbon dioxide electrocatalytic reduction (CO2RR) can simultaneously realize the conversion and utilization of carbon dioxide and the efficient storage of renewable clean electricity, which is conducive to the construction of a sustainable carbon resource recycling network. In recent years, the research team has carried out a unique and in-depth systematic study of CO2 electrocatalytic reduction from the perspective of catalysis, and achieved a series of research results in nano-Pd-based catalysts, metal-oxide interfaces, etc., significantly improving CO2 electrocatalysis. The selectivity, activity and stability of the reduction (J. Am. Chem. Soc., Chem. Sci., J. Am. Chem. Soc., ACS Catal., Angew. Chem. Int. Ed.).

Transition metal-nitrogen-carbon composites are an electrocatalytic material that is expected to replace noble metals. The research team recently focused on the controlled preparation of such materials and their electrocatalytic properties (Energy Environ.Sci., Nano Energy, ACS Catal). .). Previous studies have shown that transition metal-nitrogen-carbon composites can reduce CO2 by electrocatalytic reduction to produce CO, but as the overpotential increases, the competitive hydrogen evolution reaction (HER) current increases drastically, resulting in a rapid decline in the CO Faraday efficiency. Get high CO current density. Therefore, achieving high CO2RR current density and Faradaic efficiency at the same time is an important challenge for transition metal-nitrogen-carbon composites.

In this study, the team succeeded in preparing a porous Ni-N-doped porous carbon material that is monodispersed by pyrolyzing a zinc/nickel bimetallic zeolite imidazole skeleton (ZIF-8). Ni species load up to 5.44wt%. On this Ni-N catalyst, CO Faradaic efficiency was maintained between 92.0% and 98.0% in the wide potential range from -0.53V to -1.03V (vs. RHE). The CO current density increased with the overpotential, in - 1.03 V (vs. RHE) reached 71.5±2.9 mA/cm 2 . The characterization results and comparative experiments show that the coordination unsaturated Ni-N is the active site; the density functional theory calculations further reveal that CO2RR is more probable than HER in the NiN2V2 (V stands for vacancy) position. It is speculated that NiN2V2 may be the active bit of CO2RR. . Therefore, the high-loaded coordination of unsaturated Ni-N active sites simultaneously achieves high current density and Faradaic efficiency of CO2RR, breaking the "seesawboard" effect limit of CO2RR selectivity and reaction rate on transition metal-nitrogen-carbon composites.

The above research work has been funded by the National Natural Science Foundation of China, the National Key R&D Program, the DMTO, and the pilot projects of the Chinese Academy of Sciences.