Rational electrocatalyst design for selective nitrate reduction to ammonia

The electrocatalytic nitrate (NO3−) reduction reaction (NO3RR) is an attractive strategy for sustainable ammonia (NH3) synthesis, contributing to the artificial nitrogen cycle and renewable energy storage. However, selective conversion of NO3− to NH3 remains challenging due to the complex multi-electron transfer processes, which result in numerous by-products, low NH3 yield rate, and Faradaic efficiency. Additionally, the electrochemical sensitivity of the catalyst structure complicates identifying the active sites. Herein, we introduce the mechanisms and in situ characterization technologies of NO3RR to NH3 production. Then, a summary of the theoretical research advances NO3RR to guide the design of the catalyst, including density functional theory calculations, activity descriptors, and machine learning. Furthermore, we discuss strategies to optimize the performance of NO3RR, focusing on nitrogenous-intermediate adsorption, proton adsorption, and tandem catalysis. Finally, the challenges and opportunities of highly efficient NO3RR are summarized.