Dual‐Coordinated Cu(I) Sites Immobilized on Ti ₃ C ₂ T <i> _x </i> MXene for Efficient Conversion of Low‐Concentration Nitrate toward Ammonia

Abstract Copper‐based materials have emerged as promising electrocatalysts for nitrate reduction. However, achieving efficient nitrate‐to‐ammonia conversion at low concentrations (usually ≤ 10 mmol L −1 ) under neutral conditions remains a grand challenge. Here cooperative dual Cu + sites are crafted on Ti 3 C 2 T x MXene via coordination with the surface −O and −Cl functional groups, using an in situ self‐reduction strategy, for electrochemical nitrate reduction. The resulting dual‐active‐site Cu(I)/Ti 3 C 2 T x electrocatalyst achieves a NO 3 − removal efficiency of 97.6% and an ammonia selectivity of 94.7% in neutral wastewater containing 100 mg L −1 NO 3 − at −0.8 V versus the reversible hydrogen electrode (RHE). Mechanistic investigations using in situ Raman spectroscopy, online differential electrochemical mass spectrometry (DEMS), and quantum chemical calculations reveal that the dual Cu + sites, in conjunction with hydrogen‐spillover facilitated by the Ti 3 C 2 T x MXene, significantly enhance water dissociation to produce more absorbed active hydrogen. This process lowers the energy barrier for hydrogenating the *NO intermediate, which is regarded as the rate‐determining step in Cu‐based catalysts. Further the feasibility of an electrochemical NO 3 − reduction‐coupled hydroponic fertilizing system is demonstrated for enabling simultaneous nitrate removal and wheat cultivation. This work provides a new paradigm for designing electrocatalysts to advance the “waste‐to‐wealth” conversion of nitrate‐containing wastewater for sustainable agriculture.