Tin‐modified Cu 2 O catalysts for enhanced C‐C coupling in CO 2 electroreduction

Abstract Regulating local surface environment of Cu‐based catalysts is essential for improving multi‐carbon (C 2+ ) formation in electrochemical CO 2 reduction, where limited intermediate availability often constrains C‐C coupling. Herein, Sn‐modified Cu 2 O catalysts were synthesized via a solvothermal strategy to tune local reaction environment. Structural characterizations suggest that Sn is present as surface‐associated SnO x species spatially associated with Cu‐O catalyst region, accompanied by changes in Cu surface chemical environment. The optimized Sn 0.05 Cu catalyst achieves a Faradaic efficiency of 67.8% toward C 2+ products (50.4% for C 2 H 4 ) at −1.4 V vs. RHE with stable operation over 50 h. Operando spectroscopy suggests an enhanced *CO‐related response and a changed adsorbate distribution, consistent with the increased C 2 /C 1 ratio while DFT calculation results indicate that SnO x ‐associated local environments can electronically perturb neighboring Cu sites and favor *CO‐derived C‐C coupling energetics. Thus, surface‐associated SnO x modification could provide a viable strategy for improving multi‐carbon formation in CO 2 electroreduction.