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 mg_cat ^-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.