Iron-doped NiS2 microcrystals with exposed {001} facets for electrocatalytic water oxidation.

Abstract

Developing high-performance electrocatalysts with favorable phase, surface structure and electronic structure for oxygen evolution reaction (OER) is crucial for efficient electrocatalytic water splitting. With Fe3+ ions as both dopant and morphology-controlling agent, Fe-doped NiS2 microcrystals with the exposed chemically stable {001} facets were synthesized hydrothermally for electrocatalytic OER. The initial electrocatalytic OER activation processes led to the conversion of iron-rich surface layers of the NiS2 microcrystals into Fe-doped Ni (oxy)hydroxide as the shell and the residual inner of the NiS2 microcrystals as the core. Such Fe-doped NiS2 microcrystals with the derived core/shell structure only required a small OER overpotential of 277\xa0mV to reach an electrochemical current density of 10\xa0mA/cm2, and showed a good stability in a more than 20\xa0h duration test almost without overpotential increase.