Selective electroreduction of nitrate to ammonia with high Faradaic efficiency on nanocrystalline silver

Electrocatalytic reduction of nitrate to ammonia is a promising approach to both green synthesis of ammonia and nitrate pollution disposal. However, current cathode catalysts display relatively low selectivity and Faradaic efficiency. We demonstrate here that nanocrystalline silver (nano-Ag) can achieve both high selectivity and high Faradaic efficiency. Nano-Ag at −0.33 V vs. RHE delivers a current density of −194.31 mA cm−2, exhibits a Faradaic efficiency of up to 96.4% and has selectivity of 89.6%. It also exhibits good stability, retaining 91.1% of the original selectivity and about 100% of the original Faradaic efficiency after 4 cycles, suggesting that nano-Ag is a highly efficient catalyst for reduction of nitrate to ammonia.