Self-Adaptive Co-W Heteroatomic Interfaces for Efficient and Stable Nitrate-To-Ammonia Conversion

To break the selectivity-activity trade-off in nitrate reduction, we report a self-adaptive W single-atom-anchored CoOOH matrix that constructs Co-W heteroatomic interfaces (referred to as W-CoOOH) created via a spontaneous etching-reconstruction process. Operando analysis demonstrates that a reversible electron relay between the Co-W heteroatomic interfaces, which stabilizes the Co-W dual active sites during nitrate reduction reaction (NITRR). This adaptive electronic structure enables exceptional performance, including a Faradaic efficiency (FE) over 90% in a wide potential range (0 to -0.8 V vs. reversible hydrogen electrode (RHE) and a high NH₃ yield rate of 0.64 g h^-1 at 10 A using a 5 × 5 cm² membrane electrode assembly (MEA). Mechanistic investigations, combining in situ spectroscopy and theoretical calculations, support a local Co-W interfacial bifunctional pathway in which Co sites preferentially adsorb/activate NO₃ ^--derived intermediates, while W-associated interfacial sites facilitate H₂O dissociation and increase the local availability of hydrogen species for subsequent hydrogenation steps. This dual-site cooperation is further accompanied by interfacial electronic modulation, which together contributes to the superior NITRR performance of W-CoOOH.