Lewis acid sites and flexible active center synergistically boost efficient electrochemical ammonia synthesis

Much effort has been carried out to develop efficient electrochemical catalysts for nitrogen reduction reaction (NRR). However, the activity and selectivity of present catalysts are still limited in their applications. Herein, from the perspective of Lewis acid-base interactions and flexible active center, the positively charged tetrahedron transition metal (TM) clusters were anchored into boron nitride nanotubes (BNNTs) with B-vacancies to design a series of efficient NRR catalysts, meeting the above requirements. Through Density Functional Theory (DFT) calculations, our results uncover that the Mn4/BNNT (6, 6) system exhibits optimal activity characterized by a low limiting potential of only -0.29 V and a high selectivity confirmed by an adsorption energy difference between nitrogen molecules and hydrogen proton (-0.73 eV). Owing to the existence of electron-deficient Lewis acid sites, the adsorption and activation for N2 are strongly enhanced. Simultaneously, the flexible active center destabilizes the N-containing intermediates and upgrades the hydrogenation reaction process, making NH3 easy to desorb or further hydrogenate to NH4+. This innovative approach, employing Lewis acid pair and flexible active center to design efficient NRR catalysts, holds great promise for NH3 synthesis under ambient conditions.