Progress and prospects of electrochemical reduction of nitrate to restore the nitrogen cycle

Nitrate pollution has become a serious global problem due to the development of the nitrogen fertilizer industry, which poses a threat to the ecosystem and human health. Electrochemical reduction is an energy-efficient and environmentally friendly technology for removing nitrate from water. This paper focuses on the electrocatalyst materials used for nitrate reduction, including noble metal catalysts, non-noble metal catalysts (transition metal catalysts, transition metal compound catalysts, transition metal composite catalysts, and single-atom catalysts), and non-metallic catalysts. Next, the electrochemical nitrate reduction mechanisms and pathways are discussed, along with the undesirable products they can yield, such as nitrite and ammonium. The factors that affect the conversion and selectivity of electrochemical nitrate reduction, such as electrolyte design and electrode material construction, are briefly described. Finally, the challenges and possible prospects facing the field are discussed, along with opinions and perspectives. This manuscript provides a comprehensive overview of the current state of research on the electrochemical reduction of nitrate.