Unveiling the Synergy of O-Vacancy and Heterostructure over MoO3-x/MXene for N2 Electroreduction to NH3

The electrochemical N-2 reduction reaction (NRR) offers a promising approach for sustainable NH3 production, and modulating the structural/electronic configurations of the catalyst materials with optimized electrocatalytic properties is pivotal for achieving high-efficiency NRR electrocatalysis. Herein, vacancy and heterostructure engineering are rationally integrated to explore O-vacancy-rich MoO3-x anchored on Ti3C2Tx-MXene (MoO3-x/MXene) as a highly active and selective NRR electrocatalyst, achieving an exceptional NRR activity with an NH3 yield of 95.8 mu g h(-1) mg(-1) (-0.4 V) and a Faradaic efficiency of 22.3% (-0.3 V). A combination of in situ spectroscopy, molecular dynamics simulations and density functional theory computations is employed to unveil the synergistic effect of O-vacancies and heterostructures for the NRR, which demonstrates that O-vacancies on MoO3-x serve as the active sites for N-2 chemisorption and activation, while the MXene substrate can further regulate the O-vacancy sites to break the scaling relation to effectively stabilize *N-2/*N2H while destabilizing *NH2/*NH3, resulting in more optimized binding affinity of NRR intermediates toward reduced energy barriers and an enhanced NRR activity for MoO3-x/MXene.