Synergistic tuning of CO2 activation and *CHO adsorption enables high-rate electrocatalytic CO2 reduction to CH4 on a CuSn@N–C catalyst

Abstract

Electrochemical CO₂ reduction reaction to CH₄ (CO₂RR-to-CH₄) represents a promising strategy for valorizing CO₂ into high-value fuels and closing the artificial carbon cycle. Despite significant advances in catalyst design, most reported systems still fail to achieve industrially relevant current densities—even with optimized CO₂ activation or enhanced adsorption of the key *CHO intermediate. To address this bottleneck, we herein report a “two-in-one” CuSn bimetallic nanoparticle-decorated nitrogen-doped carbon catalyst (CuSn@N–C), which synergistically promotes CO₂ activation and *CHO intermediate adsorption to simultaneously boost the activity and selectivity of CO₂RR-to- CH₄. The CuSn@N–C catalyst exhibits a high faradaic efficiency (FE) of ∼60% for CH₄ across a broad potential window of −1.1 to −1.3 V (vs. the reversible hydrogen electrode, RHE). More notably, at a moderate potential of −1.2 V (vs. RHE), it achieves a remarkable CH₄ partial current density (j_CH4) of −262.2 mA cm⁻²—a value that outperforms most previously reported CO₂RR-to-CH₄ catalysts. Systematic control experiments and density functional theory (DFT) simulations were conducted to elucidate the catalytic mechanism. The N–C support plays a critical role in facilitating CO₂ activation, while the Sn component in the CuSn bimetallic nanoparticles optimizes the adsorption energy of the *CHO intermediate. This work not only provides a high-performance catalyst for CO₂RR-to-CH₄ but also proposes a generalizable strategy to enhance CH₄ production by co-regulating CO₂ activation and key intermediate adsorption.