Atomic Doping Engineering in Electrocatalytic Nitrate to Ammonia Conversion

In recent years, the electrocatalytic nitrate reduction reaction (eNitRR) has attracted growing interest in energy and environmental science. This technology enables the efficient and environmentally friendly synthesis of high-value ammonia (NH₃). It can also remove nitrate from contaminated water. However, eNitRR exhibits slow kinetics, involving a variety of intermediates, different product types, and multiple reaction pathways. The hydrogen evolution reaction (HER) also competes with eNitRR for protons and electrons. These inherent challenges limit the efficient reduction of nitrates. Atomic doping engineering offers an effective strategy to address this problem. This review systematically discusses the mechanism of eNitRR and side reactions. In the section on the effects of doping on eNitRR, the mechanism by which doping regulates active sites is discussed from four perspectives: adsorption behavior, charge transfer, reaction pathways, and active site density, providing helpful guidance for the rational design of eNitRR catalysts. In addition, synthesis strategies for doped catalysts are summarized, along with recent progress in noble metal doping, non-noble metal doping, nonmetal doping, and codoping. This review also discusses opportunities and research directions for future development of doping engineering in eNitRR, aiming to provide useful guidance for the design of high-performance eNitRR catalysts.