Electrochemical synthesis of nitric acid from air and ammonia through waste utilization

Commercial nitric acid (HNO(3)) and ammonia (NH(3)) are mostly produced through the Ostwald process and the Haber-Bosch process, respectively. However, high energy demand and enormous greenhouse gas accompy these processes. The development of economical and green ways to synthesize HNO(3) and NH(3) is highly desirable for solving the global energy and environmental crisis. Here, we present two energy-efficient and environmentally friendly strategies to synthesize HNO(3) and NH(3) at distributed sources, including the electrocatalytic oxidation of N(2) in air to HNO(3) and the electrocatalytic reduction of residual [Formula: see text] contamination in water to NH(3). The isotope-labeling studies combined with theoretical calculation reveal the reaction path of the two proposed strategies, confirming the origin of the electrochemical products. Importantly, the electrooxidation-generated [Formula: see text] ions may also serve as reactants for the electroreduction synthesis of NH(3) in the future. Our work may open avenues for energy-efficient and green production of HNO(3) and NH(3) at distributed sources.