Aqueous Electroreduction of Nitric Oxide to Ammonia at Low Concentration via Vacancy Engineered FeOCl

Abstract Electroreduction of nitric oxide (NO) to NH 3 (NORR) has gained extensive attention for the sake of low carbon emission and air pollutant treatment. Unfortunately, NORR is greatly hindered by its sluggish kinetics, especially under low concentrations of NO. Herein, we developed a chlorine (Cl) vacancy strategy to overcome this limitation over FeOCl nanosheets (FeOCl‐V Cl ). Density functional theory (DFT) calculations revealed that the Cl vacancy resulted in defective Fe with sharp d‐states characteristics in FeOCl‐V Cl to enhance the absorption and activation of NO. In situ X‐ray absorption near‐edge structure (XANES) and attenuated total reflection‐infrared spectroscopy (ATR‐IR) verified the lower average oxidation state of defective Fe to enhance the electron transfer for NO adsorption/activation and facilitate the generation of key NHO and NH x intermediates. As a result, the FeOCl‐V Cl exhibited superior NORR activities with the NH 3 Faradaic efficiency up to 91.1 % while maintaining a high NH 3 yield rate of 455.4 μg cm −2 h −1 under 1.0 vol % NO concentration, competitive with those of previously reported literatures under higher NO concentration. Further, the assembled Zn‐NO battery utilizing FeOCl‐V Cl as cathode delivered a record peak power density of 6.2 mW cm −2 , offering a new route for simultaneous NO removal, NH 3 production, and energy supply.