Sulphur doping of nickel ferrite nanosheet array for enhanced water oxidation

Abstract

Industrial water electrolysis requires highly-active and ampere-current-bearing oxygen evolution reaction (OER) catalysts, but achieving such a large operating current density at low overpotentials in available OER catalysts still remains a grand challenge. Herein, we report a facile and conventional strategy to grow vertically non-metallic modified nickel ferrite nanosheets on Fe foam (S-NiFe2O4/IF) as largecurrent-density OER catalysts. The vertically aligned nanosheet arrays can offer large electrochemical surface area, and the spacing between nanoarrays can allow for effective electrolyte access to the active sites. The introduction of S enhanced the adsorption and dissociation to water and optimized the adsorption of OER intermediates. As a result, S-NiFe2O4/IF exhibits superior OER activity with an overpotential of 287 and 326 mV to achieve 100 and 500 mA cm−2, respectively, and displays robust stability in alkaline media. In addition, the synthesis strategy developed here can be applied to other mixed transition metal oxides with similar selfsupported earth-abundant nanoarrays for advanced electrocatalysis in energy-related reactions.