FeS 2 nanoparticles on reduced graphene oxide: an efficient electrocatalyst for nitrate electroreduction to ammonia.

Electrocatalytic nitrate-to-ammonia conversion (NO 3 RR) represents a promising approach for achieving both sustainable NH 3 synthesis and wastewater treatment. Herein, we first demonstrate the great feasibility of using pyrite FeS 2 as an effective and durable NO 3 RR catalyst. The developed FeS 2 nanoparticles supported on reduced graphene oxide (FeS 2 /RGO) deliver the maximum NH 3 -Faradaic efficiency of 83.7% with a corresponding NH 3 yield of 2.32 mg h -1 cm -2 at -0.6 V (RHE). FeS 2 /RGO also exhibits excellent stability during the cycling and long-term electrolysis tests. DFT calculations reveal that NO 3 - can be efficiently activated on surface Fe sites, which can drive the NO 3 RR process through an NHO pathway with a low energy barrier.