Ultrathin Pd-Loaded Cu2o Stabilises Cu+ to Facilitate Electrochemical Co2 Reduction Reaction

Abstract

Copper oxides exhibit significant potential for catalytic activity in the electrochemical CO2 reduction reaction (CO2RR), particularly Cu2O. However, the rapid reduction of Cu+ to metallic Cu leads to catalyst deactivation, significantly impacting product selectivity and stability. This study aims to stabilize the Cu+ valence state at a metal-Cu2O heterogeneous interface through interfacial engineering, ultimately enhancing the electrochemical CO2 reduction performance of Cu2O. Utilizing comprehensive in situ Raman spectroscopy, we observed that the addition of Pd effectively inhibited the reduction of Cu2O. Additionally, combined in situ attenuated total reflection Fourier-transform infrared spectroscopy and theoretical calculations revealed that Pd loading enhances *CO intermediate concentration and adsorption energy, and reduces the energy barrier for *CHO formation. The improved stability of the Cu+ valence state led to the coexistence of two CO adsorption modes including COatop and CObridge, promoting further CO hydrogenation and C-C coupling. Consequently, the Pd-loaded Cu2O catalyst demonstrated remarkable electrochemical CO2RR performance, achieving a CH3OH Faradaic efficiency of 78% at -0.75 V in KHCO3 electrolyte.

Keywords: Pd loading, Cu+ stability, electrochemical CO2 reduction, CH3OH production, catalytic mechanism