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

Abstract

CO2 electrochemical reduction reaction (CO2RR) 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) and Bi nanoparticles (Binps) 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), the hybrid catalyst achieved a HCOOH Faradaic efficiency (FEHCOOH) 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 can maintain high stability of structures during the catalytic process, leading to no significant decay of FEHCOOH over 32 h. The enhanced performance of Inclus/Binps-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 catalyst. The tuned electronic structure results in an offset effect that optimizes the binding energy to HCOO* intermediate, thus accelerating the CO2 to HCOOH conversion, as proven by the in-situ ATR-SEIRAS and density functional theory (DFT) calculations.