Nanocrystalline NiS particles synthesized by mechanical alloying as a promising oxygen evolution electrocatalyst

•The nc-NiS particles prepared by MA exhibited promising OER electrocatalytic activity.•The study revealed that the nc-NiS particles act as the precursor to a highly active OER electrocatalyst.•The oxidation products induced by the CV1000 activation were benefit to their OER performance.•The study provided an idea to obtain better catalytic performance of Nickel sulfides. Cost-effective and efficient oxygen evolving electrocatalysts are urgently required for energy conversion technology. In this work, nanocrystalline NiS particles were prepared by a facile one-step mechanical alloying method as a promising oxygen evolution reaction electrocatalyst. The nanocrystalline NiS catalysts exhibited an overpotential of 354 mV at the current density of 10 mA cm−2 after 1000 cycles Cyclic voltammetry scan activation in alkaline electrolyte (1 M KOH). The Tafel slope reduced 33% to 116 mV/dec after the activation. The working electrode could maintain its 81.3% catalytic activity after the 10 h long-term test. The improved OER performance of the nc-NiS catalysts was benefit from the changes on the morphology and composition, which were induced by the CV1000 activation.