Vanadium defect-engineering in molybdenum disulfide for electrochemical nitrate reduction

The electrochemical nitrate reduction reaction (NITRR) provides a promising option for nitrate pollutant removal and ammonia production under ambient conditions, which requires electrocatalysts with high activity. Here, bio-inspired metalloenzymes MoS₂ nanoflowers with defect-engineering via vanadium doping (V–MoS₂) prepared by a one-step hydrothermal method are verified to show remarkable NITRR capability. The introduction of highly conductive vanadium changes the electron orbitals and the metalloenzyme-like structure of the MoS₂, making the 15% V–MoS₂ catalyst exhibit a high-efficiency nitrate removal rate of 95% and excellent ammonia selectivity of 89.5% at −1.1 V versus the reversible hydrogen electrode (RHE) in 0.5 M Na₂SO₄ solution. Density functional theory (DFT) calculations reveal that the reduced energy barrier of 0.41 eV, correlated with hydrogenation of *NO to *NOH, plays a crucial part in the enhanced nitrate removal rate and NH₄⁺ selectivity of V–MoS₂. This work opens up a new avenue for the design of bio-inspired metalloenzyme catalysts for the NITRR.