FeNi 3 nanosheets with multiple defects induced by H + -ion irradiation show enhanced electrocatalytic action during the oxygen evolution reaction

The oxygen evolution reaction (OER) is vital in electrocatalytic water-splitting. However, efficient non-precious metal electrocatalysts are required to improve the reaction efficiency. Therefore, this study aims to increase the OER activity of FeNi 3 nanosheets using high-energy H + -ion irradiation to create multiple defects. The optimized sample (FeNi 3 -16) achieves a lower overpotential of 260 mV at a current density of 10 mA cm −2 than its pristine counterpart (FeNi 3, 320 mV). Density functional theory (DFT) calculations show that the multiple defects in Fe and Ni can synergistically reduce the d-band centres of the Fe and Ni sites, which improves the electron transfer efficiency during the OER. This ion-irradiation technique may be applied to other electrocatalysts for various energy device.