Carbon‐Bifunctionalized Mo 2 N Coupled Atomic Pb Sites for Efficient Nitrogen Reduction

Abstract The electrocatalytic nitrogen reduction reaction (ENRR) offers a sustainable pathway for ambient ammonia (NH 3 ) synthesis but suffers from kinetic limitations and competing hydrogen evolution (HER). Herein, a new type of ENRR catalyst is designed consisting of carbon‐bifunctionalized Mo 2 N nanoparticles (NPs) embedded in a hierarchical porous carbon matrix with atomic Pb sites (PbNC) through a one‐step carbonitridation strategy. The carbon‐bifunctionalization effect not only creates nitrogen vacancies through interstitial carbon doping to form molybdenum carbonitride (Mo 2 CN) phase that enhances N 2 adsorption and activation, but also stabilizes active sites via nanoconfinement of the in situ formed carbon layer on Mo 2 CN NPs. Concurrently, the atomically dispersed Pb within the PbNC matrix suppresses HER due to its weak H * affinity. The optimized catalyst demonstrates 38.7 µg h −1 mg −1 NH 3 yield at a low potential of −0.1 V with 50 h operational stability. Density functional theory calculations reveal that carbon‐induced nitrogen vacancies modulate the Mo d‐band center, which facilitates electron back‐donation to N 2 and thus shifts the potential‐determining step from initial protonation to the NH 3 desorption step via the Mars‐van Krevelen mechanism with a lower energy barrier for ENRR. This study proposes an integrated approach involving vacancy engineering, atomic‐level HER suppression, and nanoconfinement toward efficient ENRR catalysis.