A comprehensive study on electrochemical approaches to NH3 synthesis: The role of different electrolytes

Electrochemical synthesis of NH3 (NH₃) has emerged as a promising alternative to the energy-intensive Haber–Bosch process, offering the potential for sustainable and decentralized nitrogen fixation powered by renewable energy sources. The choice of electrolyte plays a critical role in determining the efficiency, selectivity, and scalability of electrochemical nitrogen reduction, as it governs ion transport, reaction kinetics, and catalyst–electrolyte interfacial interactions. This review provides a comprehensive overview of recent advances in NH₃ synthesis across diverse electrolyte systems, including aqueous electrolytes, proton-conducting polymers, solid oxide electrolytes, molten salts electrolytes, room-temperature ionic liquids (RTILs), proton-coupled electron transfer (PCET) systems, ceramic/inorganic proton-conducting solids, and organic (lithium-mediated) electrolytes. We analyze the physicochemical properties, mechanistic roles, advantages, and key limitations of each electrolyte class in facilitating nitrogen reduction while suppressing competing side reactions such as the hydrogen evolution reaction (HER). Emphasis is placed on the interplay between electrolyte composition and catalyst performance, strategies to enhance faradaic efficiency and approaches to improve system stability and scalability. Furthermore, we explore emerging concepts such as hybrid electrolyte systems, electrolyte-induced selectivity tuning, and the application of operando characterization techniques to unravel reaction mechanisms. This review aims to highlight the critical importance of electrolyte design in advancing electrochemical NH3 synthesis and to outline future research directions toward efficient, selective, and industrially viable nitrogen fixation technologies.