Multiple Active Sites Engineering in Cu/γ‐Al ₂ O ₃ Catalyst Enables Selective Electrocatalytic CO ₂ Reduction to Methane at High Rates

ABSTRACT The electrocatalytic reduction of CO ₂ (CO ₂ RR) to methane (CH ₄ ) using renewable electricity represents a pivotal technology for closing the anthropogenic carbon cycle. However, achieving high CH ₄ Faradaic efficiency at industrially relevant current density remains challenging. This is primarily due to the complex multiple adsorption, activation, and reaction steps for CH ₄ production, in which each process needs to occur efficiently at its matching catalytic active sites, so the kinetic bottlenecks exceed the capacity of single or dual‐site catalysts. To address this, we engineered a Cu/Al‐based multi‐site heterogeneous electrocatalyst featuring atomically dispersed Cu clusters (1.5 wt.%) on a γ‐Al ₂ O ₃ matrix. Experimental and theoretical studies reveal that Cu and γ‐Al ₂ O ₃ sites predominantly serve as CO ₂ (forming *CO) and H ₂ O molecule (yielding *H) activation centers, respectively, whereas Cu/γ‐Al ₂ O ₃ interfacial sites primarily accelerate the *CO and *H coupling to form rate‐determining step intermediates (*CHO). The optimized Cu _{1.5 wt.%} /γ‐Al ₂ O ₃ multi‐site catalyst exhibited a high CH ₄ Faradaic efficiency of 72% at the current density of 500 mA cm ⁻² , outperforming the reported Cu‐based single‐site and dual‐site catalysts. This study establishes combinatorial site engineering as a paradigm for overcoming scaling relations in multi‐step CO ₂ hydrogenation, with broad applicability in catalyst design.