Lattice Distortion Broadens the e_<i>g</i> Band of Co₃O₄ to Facilitate p-d Hybridization for Enhanced Electrochemical Nitrate Synthesis

The electrochemical nitrogen oxidation reaction (NOR) presents a sustainable pathway for nitrate synthesis under mild conditions; however, the process is hindered by the inadequate adsorption and activation of N₂ on electrocatalysts. In this study, we utilized Co₃O₄ as a model catalyst and engineered lattice distortions by introducing oxygen vacancies, which expanded the e_<i>g</i> band of the active sites to enhance N₂ activation. The modified Co₃O₄ catalyst achieved a Faradaic efficiency of 10.68% and a nitrate yield of 58.80 μg·h^-1·mg_cat^-1. Comprehensive experimental and density functional theory (DFT) analyses demonstrated that these modifications resulted in a shortened Co-N bond length and an elongated N≡N bond, leading to improved p-d hybridization between N₂ and Co sites. Moreover, the enhancements in catalytic performance were also attributed to the improved electron transfer properties stemming from the altered band structure of Co₃O₄. This work provides innovative design principles for catalysts aimed at facilitating complex electrocatalytic reactions with multiple kinetics.