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.