Electron-Deficient Bimetallic Oxide Electrocatalyst for High-Efficiency Ammonia Synthesis Under Ambient Conditions.

Ammonia (NH3) is an essential feedstock for fertilizers and a promising carrier for carbon-free hydrogen fuel. However, its conventional production through the energy-intensive Haber-Bosch process results in significant carbon dioxide emissions. Here, we report an eco-friendly solid-state synthesis of bismuth vanadium oxide supported on treated carbon black (Bi4V6O21@CB), denoted as BV64@CB, as an efficient electrocatalyst for the nitrogen reduction reaction (NRR). This electrocatalyst exhibits exceptional activity owing to its unique coordination environment, which effectively sustains electron deficiencies. In this system, vanadium (V5+) active sites facilitate nitrogen (N2) adsorption, while bismuth (Bi3+) promotes the hydrogenation of adsorbed N2, leading to the formation of *NNH intermediates on the BV64@CB surface. The cooperation between vanadium and bismuth enhances NRR efficiency, thereby promoting NH3 synthesis via the distal associative pathway. These mechanistic insights are supported by in situ X-ray absorption spectroscopy and Raman analyses. The BV64@CB electrocatalyst exhibits an impressive average NH3 yield rate of 370.1 μg h-1 mgcat -1 and a Faradaic efficiency of 90.94% at -0.4 V versus the reversible hydrogen electrode in a 0.2 M Li2SO4 electrolyte (pH 5). This performance surpasses that of other bimetallic oxide electrocatalysts, underscoring its potential as an efficient and sustainable candidate for NH3 synthesis.