Coupling In nanoclusters and Bi nanoparticles in nitrogen-doped carbon for enhanced CO2 electroreduction to HCOOH

CO2 2 electrochemical reduction reaction (CO2RR) 2 RR) to formic acid (HCOOH) is beneficial for the recycling of carbon resources, which needs the highly selective catalysts with long-term stability for HCOOH production. In this study, the coupling of In nanoclusters (Inclus) clus ) and Bi nanoparticles (Binps) nps ) in nitrogen-doped carbon was designed by the thermal decomposition of the mixture of bimetallic MOFs and dicyanamide. When the In/Bi molar ratio was 1:2 (Inclus/Binps-1:2), clus /Bi nps-1:2), the hybrid catalyst achieved a HCOOH Faradaic efficiency (FE HCOOH ) of 94.5 % at-1.1 V vs reversible hydrogen electrode (RHE) in an H-type electrolysis cell, superior to that of single metal counterparts. Moreover, the Inclus/Binps-1:2 clus /Bi nps-1:2 can maintain high stability of structures during the catalytic process, leading to no significant decay of FE HCOOH over 32 h. The enhanced performance of Inclus/Binps-1:2 clus /Bi nps-1:2 is attributed to the strong electron interactions induced by the charge transfer between the In and Bi sites in Inclus/Binps-1:2 clus /Bi nps- 1: 2 catalyst. The tuned electronic structure results in an offset effect that optimizes the binding energy to HCOO* intermediate, thus accelerating the CO2 2 to HCOOH conversion, as proven by the in-situ ATR-SEIRAS and density functional theory (DFT) calculations.