High-efficiency ammonia synthesis via electrochemical nitrate reduction over Co₃O₄ nanoarrays by B doping

Electrochemical conversion of nitrate to valuable ammonia (NH3) is a green and widely used approach to NH3 synthesis that can be an attractive and complementary alternative to the Haber-Bosch process. However, due to the multi-step reactions in the nitrate reduction pathway, there are still challenges in developing efficient catalysts that can selectively guide the reaction route towards NH3. Herein, B doping is proposed as an effective strategy to enhance nitrate conversion to NH(3 )on the Co3O4 nanoarrays, which not only improves the electrical conductivity of Co3O4, but also lowers the energy barrier of the potential-determining step. Such B-Co3O4/TM delivers a high faradaic efficiency of 94.7% and a large NH3 yield rate of 407.3 mu mol h(-1) cm(-2). Theoretical calculations further elucidate that the introduction of B enhances the adsorption characteristic of Co3O4 for NO3-, consequently facilitating the reduction kinetics.