Recent advances on electrocatalytic CO2 reduction to resources: Target products, reaction pathways and typical catalysts

Abstract

With the rapid development of the global economy and excessive consumption of fossil fuels, the energy crisis and global warming are becoming increasingly serious. Achieving carbon neutrality and controlling temperature rise have become the global consensus issues. At present, CO2 resource recovery technology has become a research hotspot, and electrocatalytic CO2 reduction reaction (CO2RR) technology is considered as a promising strategy due to its advantages of simple device, high environmental compatibility and the possibility of combination with renewable solar or wind energy sources under mild reaction conditions. This review summarizes the possible transformation pathways of one-carbon (C1), two-carbon (C2), and multi-carbon (C2+) products in CO2RR. First, CO2RR can generate formic acid or formate, carbon monoxide, formaldehyde, methanol and methane through the carboxyl pathway. Second, formic acid or formate, methane or methanol can also be generated through the methanoyl pathway. Third, on the basis of the generation of *CO and *CHx (x = 1, 2, 3, 4), C2 and even C2+ products can be further generated, such as the formation of ethanol through the alkyl-alcoholization pathway, and the production of ethylene through the alkylation pathway. The alloy catalysts (Cu-M, M = Sn, In, Ag, etc.), porous materials (MOFs, COFs, etc.), and atomically dispersed metal-based catalysts (ADMCs, M-N-C materials, etc.) of different products and their CO2RR effects are classified, which concluded that the development of catalysts with high selectivity, Faraday efficiency, current density, stability and low cost, and in-depth study of catalytic mechanism are still the current research direction of electrocatalytic CO2RR. In order to achieve efficient use of energy, it is also necessary to design electrocatalytic devices with higher mass transfer efficiency. In the future, it is a major new direction to find new green CO2RR pathways and to realize the synergistic treatment of CO2 with other substances.