The Haber-Bosch process converts nitrogen (N2) and hydrogen (H2) into ammonia (NH3) over iron-based catalysts. Today, 50% of global agriculture uses Haber-Bosch NH3 in fertilizer. Efficient synthesis requires enormous energy to achieve extreme temperatures and pressures, and the H2 is primarily derived from methane steam reforming. Hence, the Haber-Bosch process accounts for at least 1% of global greenhouse gas emissions (1). Electrochemical N2 reduction to make NH3, powered by renewable electricity under ambient conditions, could provide a localized and greener alternative. On page 1187 of this issue, Suryanto et al. (2) report highly efficient and stable electrochemical N2 reduction based on a recyclable proton donor. This study builds on earlier work showing that an electrolyte containing a lithium salt in an organic solvent with a sacrificial proton donor was unmatched in its ability to unequivocally reduce N2 (3, 4). In both studies, it is still unclear why lithium is so critical
