Interfacial engineering of core-shell Cu@Zn nanoclusters enables methane selective CO2 electroreduction via accelerated water dissociation

Cluster beam deposition enables ligand free Cu-core/Zn-shell nanoclusters. • Cu@Zn nanoclusters achieve 63.1% CH 4 FE at 200 mA cm −2 in 1 M KOH. • Zn shell promotes water dissociation to enhance proton supply for CH 4 formation. • Core-shell interfacial engineering steers CO 2 electroreduction toward methane. The electrochemical reduction of CO 2 to CH 4 offers a promising pathway for closing the carbon cycle and enabling sustainable energy conversion, yet it is fundamentally limited by sluggish reaction kinetics and competing side reactions. We report the controlled fabrication of core-shell Cu@Zn nanocluster catalysts (Cu@Zn NCs) via cluster beam deposition (CBD). Molecular dynamics simulations based on the NEP89 universal neuro-evolution potential reveal a spontaneous formation mechanism of the core-shell architecture. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) further confirms uniform quasi-spherical Cu@Zn NCs with an average size of ~5.86 nm, a well-crystallized Cu (111) core, and a continuous Zn shell. In electrocatalytic CO 2 reduction, the Cu@Zn NCs achieve a CH 4 Faradaic efficiency of up to 63.1% with a partial current density of 126.2 mA cm −2 at −1.5 V vs. RHE and a total current density of 200 mA cm −2 . Mechanistic investigations combining in situ infrared spectroscopy and hydrogen/deuterium (H/D) kinetic isotope effects (KIE) analysis reveal that the Zn shell accelerates interfacial water dissociation, providing an abundant local proton source, while simultaneously strengthening *CO adsorption on Cu sites and promoting its hydrogenation to the key *CHO intermediate. This synergistic effect suppresses *CO desorption and C C coupling pathways, thereby steering the reaction toward highly selective CH 4 formation. This work highlights the effectiveness of precise interfacial engineering in bimetallic core-shell catalysts and provides mechanistic insights for the rational design of CH 4 selective electrocatalysts for deep CO 2 hydrogenation. Download: Download high-res image (151KB) Download: Download full-size image