Electrochemical ammonia synthesis via nitrate reduction on Fe single atom catalyst

Electrochemically converting nitrate, a widespread water pollutant, back to valuable ammonia is a green and delocalized route for ammonia synthesis, and can be an appealing and supplementary alternative to the Haber-Bosch process. However, as there are other nitrate reduction pathways present, selectively guiding the reaction pathway towards ammonia is currently challenged by the lack of efficient catalysts. Here we report a selective and active nitrate reduction to ammonia on Fe single atom catalyst, with a maximal ammonia Faradaic efficiency of similar to 75% and a yield rate of up to similar to 20,000 mu gh(-1) mg(cat.)(-1) (0.46mmolh(-1) cm(-2)). Our Fe single atom catalyst can effectively prevent the N-N coupling step required for N-2 due to the lack of neighboring metal sites, promoting ammonia product selectivity. Density functional theory calculations reveal the reaction mechanisms and the potential limiting steps for nitrate reduction on atomically dispersed Fe sites.

Automated summary

The study reports a method for selectively converting nitrate to ammonia using an Fe single atom catalyst, which effectively prevents the formation of N-N coupling products while increasing the production rate of ammonia.