Synergistic Cr₂O₃@Ag Heterostructure Enhanced Electrocatalytic CO₂ Reduction to CO

Abstract The electrocatalytic CO₂RR to produce value‐added chemicals and fuels has been recognized as a promising means to reduce the reliance on fossil resources; it is, however, hindered due to the lack of high‐performance electrocatalysts. The effectiveness of sculpturing metal/metal oxides (MMO) heterostructures to enhance electrocatalytic performance toward CO₂RR has been well documented, nonetheless, the precise synergistic mechanism of MMO remains elusive. Herein, an in operando electrochemically synthesized Cr₂O₃–Ag heterostructure electrocatalyst (Cr₂O₃@Ag) is reported for efficient electrocatalytic reduction of CO₂ to CO. The obtained Cr₂O₃@Ag can readily achieve a superb FE_CO of 99.6% at −0.8 V (vs RHE) with a high J_CO of 19.0 mA cm⁻². These studies also confirm that the operando synthesized Cr₂O₃@Ag possesses high operational stability. Notably, operando Raman spectroscopy studies reveal that the markedly enhanced performance is attributable to the synergistic Cr₂O₃–Ag heterostructure induced stabilization of CO₂^•−/*COOH intermediates. DFT calculations unveil that the metallic‐Ag‐catalyzed CO₂ reduction to CO requires a 1.45 eV energy input to proceed, which is 0.93 eV higher than that of the MMO‐structured Cr₂O₃@Ag. The exemplified approaches in this work would be adoptable for design and development of high‐performance electrocatalysts for other important reactions.