Unconventional rectifying interface of bimetal/carbon catalyst act as charge emitter for efficiently bending *CO₂ to stably drive the formation of formate

Abstract

Developing metal/carbon materials as durable electrocatalysts for electrochemical CO₂ reduction is of great importance for maintaining long-term activity of metal sites. However, the uncertainty associated with the interaction of metal–carbon restricts the exposure of active sites and the inhibition of the hydrogen evolution reaction. Herein, we have successfully synthesized a hierarchical bimetal/carbon catalyst with unconventional rectifying interfaces (Bi-Sn@C), which works as a charge emitter for efficiently bending CO₂ to enhance the adsorption and hydrogenation of activated *CO₂ and the generation of *OCHO intermediate by the nucleophilic reaction process due to the electronic perturbation at rectifying interfaces and electron delocalization of the bimetallic cores. The Bi-Sn@C demonstrates up to HCOOH faradic efficiency of 93.06% with energy efficiency of 70.6% at −0.52 V (vs. RHE) and low overpotential of 320 mV in a flow electrolyzer, and operates continuously for more than 160 h due to the protective mechanisms of the carbon shell. Experimental results and theoretical calculations reveal that the hierarchical rectifying interfaces of Bi-Sn@C show an apparent non-uniform distribution of charge and low energy barrier of *OCHO-to-*HCOOH for facilitating the reaction kinetics of formate production.

Keywords

CO₂ reduction / core–shell / electrocatalysis / formate / rectifying interfaces

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