Solid-state synthesis of Cu nanoparticles embedded in carbon substrate for efficient electrochemical reduction of carbon dioxide to formic acid

Electrochemical reduction of CO₂ into formic acid (HCOOH) is an appealing approach to mitigate the CO₂ emission problem and achieve a carbon-neutral cycle but remains a challenge. Herein, we present a novel strategy to prepare Cu nanoparticles embedded in carbon substrate (Cu NPs@C) as efficient CO₂ reduction reaction electrocatalysts for highly selective HCOOH production. The uniformly distributed Cu nanoparticles are responsible for the high faradaic efficiency of HCOOH of 78% at −1.0 V (RHE) and yield of 82.8 μmol h⁻¹ cm⁻² at −1.2 V (RHE). Moreover, the detailed density functional theory (DFT) calculations have demonstrated that the high activity and selectivity for HCOOH production was attributed to the synergy effects of exposed Cu (111) facets and carbon substrate. The charges transferred from Cu induces a charge-rich environment on the carbon surface, which enhances the *OCHO adsorption and boosts the HCOOH formation. This work paves a new way to synthesize novel Cu-based electrocatalysts for efficient production of HCOOH.