A review of the synthesis, characterization, and mechanism of bimetallic catalysts for electrocatalytic CO₂ reduction

The electrocatalytic CO₂ reduction reaction (CO₂RR) is an environmentally friendly way to convert CO₂ into valuable chemicals. However, CO₂ conversion is a complex process, which contains 2, 4, 6, 8, and 12 electron transfer processes. It is very important to develop efficient catalysts to precisely control the number of electron transfers for the chemicals required. Single-metal catalysts have some deficiencies, including slow reaction kinetics, low product selectivity and inadequate stability. In response to these challenges, bimetallic catalysts have received significant attention owing to their unique structure and improved performance. The introduction of secondary metals alters the catalyst’s electronic structure, and creates novel active sites, as well as optimizing their interaction with the intermediates. This review provides a comprehensive account of atomically distributed bimetals based on carbon materials and non-atomic distributed bimetals such as alloys and heterostructures, including their synthesis methods, characterization, and the outcomes of different catalysts. Catalytic mechanisms of different bimetallic catalysts are proposed and challenges encountered in the CO₂RR are considered.