Atomically Ordered Bi-Ni Intermetallics for Efficient and Sustainable Ammonia Synthesis: Enabled by Intensified p-d...

Electrocatalytic nitrate reduction (NO₃^-R) offers a dual advantage by facilitating green ammonia synthesis while providing a sustainable strategy for the remediation of nitrate-laden wastewater. However, the activation of nitrate remains a significant challenge. Herein, we engineered an atomically ordered Bi-Ni intermetallic electrocatalyst by exploiting the unique electronic properties arising from its pronounced p-d orbital hybridization. This approach substantially improves the activation of reactant species, modulates the adsorption behavior of intermediate products, and effectively inhibits the competing hydrogen evolution reaction (HER). The BiNi intermetallic achieves ammonia production with a Faradaic efficiency (FE) of 90% at ampere-level current density across a broad potential window and demonstrates robust stability over 300 h under an ultrahigh industrial current density (700 ± 100 mA cm^-2). In situ FTIR and Raman spectroscopies elucidate the evolution of key intermediates (-NH₂, *NH₃) and accelerated water dissociation for active hydrogen (*H) provision. Density functional theory (DFT) calculations verify that strong p-d orbital hybridization narrows the p-d band center gap, thereby enhancing reactant adsorption/activation, as well as improving the superior electron-donating capability during NO₃^-R. Importantly, the BiNi intermetallic efficiently treats high-concentration nitrate-laden industrial wastewater, achieving pollutant abatement rates of 97.6% along with a conversion rate to NH₄Cl of 94.5%. This work devises a cost-competitive and high-performance catalyst, achieving its engineering application in sustainable electrochemical ammonia synthesis and practical nitrate wastewater remediation.