Electronic Modulation of Bi‐Decorated Ti 3 C 2 T x MXene Toward Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia

Electrochemical nitrate reduction (NO 3 RR) provides a sustainable route for ammonia (NH 3 ) synthesis while also enabling the treatment of nitrogen‐containing wastewater. Herein, Bi nanoparticles were anchored on Ti 3 C 2 T x MXene through an in situ reduction strategy to form Bi–NP/MXene. Compared with pristine MXene, Bi–NP/MXene exhibits markedly improved NO 3 RR activity and NH 3 selectivity, achieving a Faradaic efficiency of 93.2% at −1.2 V versus reversible hydrogen electrode (RHE) and an NH 3 yield rate of 195.3 μmol h −1 cm −2 at −1.4 V versus RHE. The catalyst retains stable performance over six consecutive cycles and 1200 min of continuous electrolysis. Density functional theory calculations reveal that Bi incorporation regulates nitrate‐derived intermediate adsorption, suppresses H* binding, and reduces the energy barrier of the potential‐determining step from 1.36 to 0.74 eV. Moreover, a Zn–NO 3 − battery employing Bi–NP/MXene enables simultaneous NH 3 production and electricity generation.