Heteronuclear Bidentate Coupling of Oxygenated Intermediates Unlocking Selective and Long-Lasting Acidic CO2 Electrolysis on High-Entropy Alloys.

Acidic CO2 electrolysis circumvents low carbon utilization encountered in neutral and alkaline electrolytes. High-entropy alloys (HEAs), despite their promise for catalysis, remain unexplored in acidic CO2 electrolysis plagued by difficult control over reaction pathways on multi-metal sites and severe metal dissolution in acidic and reductive environments. Here, we unlock the first demonstration of acidic CO2 electrolysis over a mildly synthesized nano-coral HEA catalyst via rationally directed electron reordering. The tailored electron pairing effect engenders a distinctive Cu-O-C-Ag heteronuclear bidentate coupling configuration of oxygenated intermediates, which facilitates the C─O bond elongation and cleavage, substantially lowering energy barrier of the rate-determining *COOH-to-*CO conversion. Concurrently, the orchestrated charge redistribution among synergistic metal atoms strengthens intermetallic bonding, elevating the dissolution energy of constituent metals and conferring robust corrosion resistance in acidic electrolyte. The designed senary HEA catalyst delivers, for the first time, efficient acidic CO2 electroreduction, achieving near-unity CO Faradaic efficiency (FE) of 99% and sustained operation with FE exceeding 90% for over 180 h. Such catalyst also exhibits remarkable performance across pH-universal electrolytes, enabling generally applicable CO2 electrolysis. This work establishes a new paradigm for regulating intermediates adsorption on HEA structure, opening up a pathway for HEA catalysts toward acidic CO2 electrolysis.