Nitrate electroreduction: recent development in mechanistic understanding and electrocatalyst design

Ammonia, with its wide-ranging applications in global industries, plays an indispensable role in the growth and sustainability of modern society. Electrochemical nitrate reduction (eNORR) presents an environmentally friendly pathway for ammonia production, sidestepping the energy consumption and greenhouse gas emissions associated with the conventional Haber–Bosch process. However, developing efficient and selective catalysts for eNORR is challenging due to its intricate multiproton-coupled electron transfer process and the competing hydrogen evolution reaction. This review dives deep into the recent advancements in eNORR, shedding light on the mechanism through spectroscopic studies and innovative strategies for catalyst design. We first lay out the possible reaction pathways and products in eNORR and then introduce a variety of electrochemical characterizations that provide real-time insights into the reaction mechanism. We also explore strategies for rational electrocatalyst design to optimize the performance. Representative examples of advanced materials with high activity, selectivity, and stability are highlighted to underscore the progress made in this field. Finally, we outline emerging opportunities and future directions, such as developing multifunctional nanostructured catalysts through integrated computational and combinatorial approaches. This review aims to provide valuable insights and guidance for developing nitrate electroreduction and the efficient production of green ammonia in industry.