Engineering an Ordered Intermediate Phase between Disordered Phases for CO ₂ Reduction to Multicarbon Products

Electrochemical CO 2 reduction (CO 2 RR) to multicarbon (C 2 ) products provides a compelling pathway for carbon recycling and sustainable energy storage, yet achieving high C 2 selectivity remains a major challenge due to kinetic preference for C 1 products and the intrinsic difficulty of C–C bond formation. While bimetallic alloys are widely used to tune catalytic performance, their typically random atomic arrangements hinder precise control over active site electronic environments, leading to suboptimal C 1 /C 2 selectivity. Herein, we present a composition-dependent phase engineering strategy to synthesize ordered Au 1 Cu 1 intermetallic alloy, alongside disordered Au 3 Cu 1 and Au 1 Cu 3 alloys, via a polymer nanofiber-mediated approach. The long-range atomic ordering in Au 1 Cu 1 enables an optimized d-band center, critically balancing intermediate binding (e.g., *CO at −1.09 eV) for efficient C–C coupling over C 1 formation. This resulted in the Au 1 Cu 1 /CNFs catalyst reaching a peak Faradaic efficiency of 55.6% toward C 2 products at −0.5 V vs RHE. In situ characterizations and theoretical calculations confirm that its specific electronic and geometric configurations facilitate the lowest energy barrier for *CHO–*CO coupling. This work demonstrates precise atomic-level control in bimetallic alloy ordering, guiding the CO 2 RR toward valuable multicarbon products.