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

Abstract

Electrochemical CO2 reduction reaction (CO2RR) toward CH4 represents a promising strategy for valorizing CO₂ into highvalue fuel 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. reversible hydrogen electrode, RHE). More notably, at a moderate potential of -1.2 V (vs. RHE), it achieves a remarkable CH4 partial current density (jCH₄) 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.