FeS₂ nanoparticles on reduced graphene oxide: an efficient electrocatalyst for nitrate electroreduction to ammonia

Electrocatalytic nitrate-to-ammonia conversion (NO₃RR) represents a promising approach for achieving both sustainable NH₃ synthesis and wastewater treatment. Herein, we first demonstrate the great feasibility of using pyrite FeS₂ as an effective and durable NO₃RR catalyst. The developed FeS₂ nanoparticles supported on reduced graphene oxide (FeS₂/RGO) deliver the maximum NH₃-Faradaic efficiency of 83.7% with a corresponding NH₃ yield of 2.32 mg h^-1 cm^-2 at -0.6 V (RHE). FeS₂/RGO also exhibits excellent stability during the cycling and long-term electrolysis tests. DFT calculations reveal that NO₃^- can be efficiently activated on surface Fe sites, which can drive the NO₃RR process through an NHO pathway with a low energy barrier.