Abstract
With Fe3+ as both the morphology-controlling agent and dopant, Fe-doped NiS2 microcrystals with the exposed chemically stable {001} facets were synthesized hydrothermally for electrocatalytic OER. After the electrocatalytic activation, the iron-rich surface transformed into active Fe-doped nickel oxyhydroxide, while the inner {001}-oriented NiS2 retained, endowing the catalysts with high OER activity and long-term stability.
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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 mV to reach an electrochemical current density of 10 mA/cm2, and showed a good stability in a more than 20 h duration test almost without overpotential increase.