Heteroatom Ni alloyed pyrite-phase FeS2 as a pre-catalyst for enhanced oxygen evolution reaction

Highly active and low-cost electrocatalysts toward oxygen evolution reaction are urgently-needed in the field of energy conversion. Previous works have demonstrated that pyrite-phase sulfides are promising electrocatalysts for oxygen evolution reaction, however the true active materials are still undetermined. Here, we report heteroatom Ni alloying into FeS 2 crystal via a facile ball-milling reaction method to enhance electrocatalytic performances of pyrite-phase FeS 2 . A series of (Fe 1-x Ni x )S 2 nanocrystalline materials are synthesized to systematically investigate the effects of Ni alloying on FeS 2 toward oxygen evolution reaction electrocatalysis . To achieve an current density of 10 mA cm −2 , the (Fe 0.5 Ni 0.5 )S 2 at carbon fiber paper electrode requires an overpotential as low as 241 mV with a Tafel slope of 51.8 mV dec −1 in 1 M KOH solution. Further investigations reveal that the derived hybrids of Fe 3 O 4 nanoflakes and nanoporous Ni doped FeOOH are true active materials for the (Fe 0.5 Ni 0.5 )S 2 under oxygen evolution reaction conditions. This study not only reveals the true active materials of the heteroatom alloyed bimetallic sulfides, but also provides a facile strategy to regulate the formation of active materials for enhanced oxygen evolution catalysis.