Building of sub-monolayer MoS2-x structure to circumvent the scaling relations in N2-to-NH3 electrocatalysis

Finding catalysts and mechanisms for efficient electroreduction of N-2 into NH3 remains of great challenge, due to the limitation of the scaling relations and competing HER. Here we report that N-2 can be dissociated and dynamically hydrogenized on a peculiar sub-monolayer MoS2-x structure. Different with conventional surface-binding paradigms of the reaction intermediates, such a dynamic surface-binding paradigm can selectively stabilize the nitrogen intermediates and enable the circumvention of the inherent scaling relations in electrocatalysis of N-2 to NH3. Atomic resolution AC-STEM and DFT calculations confirm the atomic arrangement and a similar to 3% compressive strain in the large area of in-plane S-vacancies of sub-monolayer MoS2-x structure. Further experimental and theoretical results demonstrate that the as-designed surface tune their catalytic properties through adjusting their surface-binding to nitrogen intermediates with tunable nitrogen affinity, leading to outstanding electrocatalytic NRR performance at ultra-low overpotential (similar to 0.2 V. vs. RHE).