Two-dimensional peak-valley alternating self-supporting electrode accelerating nitrate electrocatalytic reduction: Ammonia synthesis and wastewater treatment.

A porous self-supporting titanium sheet electrode embedded with Cu sites was constructed by anodic oxidation combined with hydrothermal/pyrolysis strategy, and high ammonia yield rate and near 100 % Faradaic efficiency were achieved in the electrocatalytic conversion of nitrate. [Display omitted] • Anodic oxidation tandem hydrothermal/pyrolysis embed Cu sites in porous titanium sheets. • Ammonia yield rate and FE as high as 7292.43 μg h−1 cm−2 and 97.34 %, respectively. • Cu/PTS can efficiently catalyze eNitRR in complex water environments. • Operando ATR-FTIRAS measurements reveal the evolution of NO 3 − to NH 3. • Nitrate hazard concentration can be reduced below the limit value of WHO and US EPA. Electrochemical nitrate reduction synthesis of ammonia can use clean energy to convert low-value nitrate pollutants into high value-added ammonia yield. The development of eNitRR catalyst with high activity, high selectivity and stability is the key to achieve distributed small-scale production of nitrate. In this study, a self-supported catalyst (Cu/PTS) with high catalytic activity (for eNitRR) was constructed by anodic oxidation combined with hydrothermal/pyrolysis strategy to realize the embedding of Cu species on the substrate of porous titanium sheet. The ammonia production rate of Cu/PTS catalyzed eNitRR is as high as 7292.43 μg h−1 cm−2 (−1.0 V vs. RHE), the Faradaic efficiency is close to 100 %, reaching 97.34 %, and isotope labeling and Operando ATR-FTIRAS verified and revealed the fact that NO 3 − to NH 3 , respectively. Density functional theory calculations well reveal the roles of various components in Cu/PTS and reveal the factors for the enhancement of eNitRR performance. Thanks to the self-supporting characteristics of porous titanium sheet and the surface embedding of copper species, Cu/PTS not only have good electrochemical stability when catalyzing eNitRR, but also can drive eNitRR to operate efficiently in complex water environment. While realizing the purification of nitrate wastewater and the synthesis of ammonia, Cu/PTS can be used as a positive electrode to construct a nitrate–zinc battery to realize the dual functions of self-driven ammonia production and external power supply. [ABSTRACT FROM AUTHOR]