Decoupling competitive reactions by their differential orbital-coupling response to vacancy engineering for efficient electrocatalytic nitrogen reduction

The electrocatalytic nitrogen reduction reaction (NRR) poses formidable challenges, such as competing hydrogen evolution and poor N₂ activation. Herein, we introduce a precise electronic-structure tuning modality through controlled sulfur vacancy (V_S) engineering in 1T-MoS₂. By manipulating the V_S concentration to nearly 9.38%, the optimized catalyst (MoS₂-100) achieves an outstanding NH₃ yield of 64.50 μg h^–1 mg^–1 and a Faradaic efficiency of 15.25%, superior to most electrocatalysts reported. Mechanistic studies reveal that enhanced d-σ orbital coupling between Mo and N₂ significantly promotes N₂ activation, while the distinct orbital-coupling responses of Mo–N₂ and Mo–H to V_S concentration render a potential competition-preponderance window for NRR. This work establishes a novel paradigm for decoupling the competitive reactions by utilizing their differential sensitivity of orbital coupling to vacancy engineering. Dalian Institute of Chemical Physics, the Chinese Academy of Sciences