Copper dispersed on two-dimensional materials exhibits excellent catalytic performance for the electrochemical reduction reaction of CO2 (CO2RR). Here, Cu clusters were anchored on defective diamond graphene (Cu n /ND@GR, n = 3, 4) to form a new class of two-dimensional nano-catalysts. Based on density functional theory, the catalytic performance and selective mechanisms of these configurations were studied systematically. By anchoring the appropriate number and configuration of Cu clusters on the defective graphene, specific reduction products (e.g., CO, CH4, and CH3OH) could be obtained. In particular, the inverted triangle configuration of Cu3/ND@GR electroreduces CO2 to methane with an overpotential of only −0.53 eV. In addition, bonding analysis confirmed the stability of the Cu n /ND@GR. The product selectivity was analyzed by calculating the deformation charge density, further revealing the CO2RR mechanism. Furthermore, side reactions (e.g., hydrogen evolution reaction and competitive production of formic acid) do not hinder the CO2RR catalytic activity. This research expands the family of catalysts for the CO2RR and the application scenarios of transition metals loaded on graphene, which provides new insights into the design and preparation of composite nano-catalysts.

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Fossil fuels are still the main source of energy in today’s society, so emissions of CO2 are inevitable, but when the CO2 level in the atmosphere is too high, many environmental problems will arise, such as the greenhouse effect, among others. Electrocatalytic reduction of CO2 is one of the most important methods that one can use to reduce the amount of CO2 in the atmosphere. This paper reviews bimetallic catalysts prepared on the basis of copper materials, such as Ag, Au, Zn and Ni. The effects of different ratios of metal atoms in the bimetallic catalysts on the selectivity of CO2RR were investigated and the effects of bimetallic catalysts on the CO2RR of different ligands were also analysed. Finally, this paper points out that the real reaction of CO2RR still needs to be studied and analysed, and the effect of the specific reaction environment on selectivity has not been thoroughly studied. This article also describes some of the problems encountered so far.