Dual‐Coordinated Cu(I) Sites Immobilized on Ti3C2Tx 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.