Calcium as a Mediator for the Electrochemical Synthesis of NH3

NH3 is an important commodity chemical to make fertilizers, pharmaceuticals, textile fibers, ammunition, etc. Haber-Bosch process used to make NH3 has a massive carbon footprint associated with it and it is desired to synthesize NH3 in a sustainable manner. Li-mediated NH3 synthesis is a promising approach to make NH3 at ambient conditions and it has been widely investigated. In this letter we explore other mediators beyond Li such as Ca, Mg, Sr, Y, and V. Our DFT results suggest that Ca, and Mg are promising mediators. Hence, we experimentally investigated Ca as a mediator and the proposed process is referred to as the Ca-mediated NH3 synthesis. An NH3 FE of 15.05 ± 2.50 % was obtained from the Ca-mediated NH3 synthesis at 50 bar. This letter serves as the proof of concept for Ca-mediated NH3 synthesis and this work would motivate further research to improve the performance for Li-free ammonia synthesis.