Synthesis of Ultrathin Mesoporous CuRu Nanomeshes for Efficient Kilowatt-Level Nitrate Reduction to Ammonia.

The electrochemical conversion of abundant nitrate ions from industrial wastewater and polluted groundwater into value-added ammonia represents an important route for the sustainable development of human society. However, developing efficient and stable catalysts remains a huge challenge. Herein, the synthesis of ultrathin mesoporous CuRu nanomeshes is reported via a theory-guided ion exchange method for efficient nitrate reduction to ammonia. The prepared CuRu nanomeshes are composed of Cu atoms anchored ultrathin mesoporous Ru nanomeshes, with a thickness of ≈2-3 nm and a pore distribution between 2 and 10 nm. It offers a high nitrate reduction performance, including a positive onset potential (0.41 V), a high ammonia Faradaic efficiency (94.5%) and a highest ammonia mass activity (0.7 A mg) at 0 V up to date. Moreover, a kilowatt-level nitrate reduction is first verified in a flow electrolyzer, with the fastest reported NO removal velocity of 12.4 mmol min. In situ characterizations and theoretical calculations clearly reveal that Cu atoms can balance the energy barriers in nitrate reduction and competitive hydrogen evolution reactions, leading to improved catalytic performance.