High temperature induced S vacancies in natural molybdenite for robust electrocatalytic nitrogen reduction

Defect engineering is an important strategy to regulate electronic structure of electrocatalysts for electrochemical N₂ fixation, aiming at improving the electron state density and enhancing the adsorption and activation of inert N₂. In this paper, a high-temperature strategy to anneal the natural molybdenite under Ar atmosphere was developed, and the as-obtained molybdenite with S vacancies boosted a high activity for N₂ reduction reaction. In 0.1 M HCl, the catalyst annealed at 800 °C exhibits a high Faradic efficiency of 17.9% and a NH₃ yield of 23.38 μg h^-1 mg^-1_cat. at -0.35 V versus reversible hydrogen electrode, two times higher than that of the pristine molybdenite. The facile one-step annealing method introduces the defects (e.g., S vacancies) in the surface of the natural molybdenite particles to prepare catalysts for generating ammonia by reducing nitrogen at room temperature under ordinary pressure, promoting the development of low-carbon economic prospect.