Highly Dispersed In‐Situ Grown Bi2O3 Nanosheets on Ti3C2Tx MXene for Selective Electroreduction of Nitrate to Ammonia

Abstract Nitrate, a common pollutant in water, can be used as a nitrogen source for electrocatalytic ammonia production. Bismuth oxide (Bi 2 O 3 ) is a promising electrocatalyst because of earth‐abundance and high hydrogen overpotential. However, it also has the disadvantages of easy agglomeration and poor charge transfer. This study demonstrated that the high dispersion of Bi 2 O 3 nanosheets can be achieved through in‐situ growth on Ti 3 C 2 T x MXene nanosheets that improved the efficiency of charge transmission, and thus improving the electrocatalytic ammonia production performance. A NH 3 yield rate of ∼7.00 mg h −1 cm −2 with faradic efficiency of 91.1 % could be achieved on 11 % Bi 2 O 3 /MXene. Density functional theory (DFT) calculations, electrochemical active surface area (ECSA) and electrochemical impedance spectroscopy (EIS) proved that the excellent ammonia production performance came from the fact that bismuth oxide itself could inhibit hydrogen evolution, and in situ growth on MXene enabled high active site exposure and enhanced charge transfer capacity.