Entropy-Derived Synthesis of the CuPd Sub-1nm Alloy for CO₂-to-acetate Electroreduction

Bimetallic alloys exhibit remarkable properties in catalysis and energy storage, while their precise synthesis at the subnanoscale remains a formidable challenge due to their immiscible nature in thermodynamics. In this study, we engineer an atomically dispersed CuPd alloy with an average size of 1.5 nm loaded on CuO and phosphomolybdic acid (PMA) coassembly subnanosheets (CuO-PMA SNSs). Driven by the high vibrational entropy, Cu atoms could escape from CuO supports and bond with adjacent Pd single atoms, leading to the in situ formation of CuPd alloys. Furthermore, this strategy can also be utilized for synthesizing the ZnPt alloy with an average size of 1 nm, thereby providing a general pathway for the design of immiscible subnanoalloys. The fully exposed Cu-Pd pairs in CuPd subnanoalloys significantly enhance the adsorption and coverage of surface *CO during the electrochemical reduction of CO₂, thereby leading to enhanced stability of ethenone intermediates and facilitating the production of C₂ compounds. The resulting CuPd subnanoalloy exhibits a remarkable Faradaic efficiency of 46.5 ± 2.1% for CO₂-to-acetate electroreduction and achieves a high acetate productivity of 99 ± 2.8 μmol cm^-2 at -0.7 V versus RHE.