Electronic Modulation of Fe Sites in Hierarchical FeOOH for Lowering the Oxygen Evolution Energy Barrier

Abstract

For the oxygen evolution reaction (OER), achieving precise electronic modulation of the active centers in metal (oxy)hydroxides (MOOH) remains a considerable challenge. Herein, we demonstrate that Ni doping effectively optimizes the electronic structure of Fe sites in FeOOH, leading to enhanced electrical conductivity and promoted charge transfer to oxygen-containing intermediates. This electronic modification strengthens the adsorption of reactants and significantly boosts the intrinsic OER activity of the Fe sites in Ni-FeOOH. Ni-doped FeOOH nanosheets are directly cover on Fe2O3 nanorods through a spontaneous metal corrosion strategy at room temperature. The unique hierarchical structure promotes the exposure of active sites and facilitates mass transfer. The optimized IF/Fe2O3@Ni-FeOOH-6 demonstrates exceptional OER performance, achieving an overpotential of 220 mV at 10 mA cm -2 and a Tafel slope of 26.6 mV dec -1 in alkaline media. Density functional theory simulations and electrochemical measurements indicate that the enhanced OER activity is due to Ni-doping, which effectively modulates the electronic structure of Fe sites, thereby lowering the reaction energy barrier for *OH → *O. This work provides a cost-effective and sustainable strategy for incorporating Ni into FeOOH and altering the local electronic structure of Fe sites.