Surface-mediated iron on porous cobalt oxide with high energy state for efficient water oxidation electrocatalysis

Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts. However, its realization in a controllable level remains challenging. Using oxygen evolution reaction (OER) as a model reaction, we report a surface-mediated Fe deposition strategy to electronically tailor surface energy states of porous Co3O4 (Fe-pCo3O4) for enhanced activity towards OER. The Fe-pCo3O4 exhibits a low overpotential of 280 mV to reach an OER current density of 100 mA cm−2, and a fast-kinetic behavior with a low Tafel slop of 58.2 mV dec−1, outperforming Co3O4-based OER catalysts recently reported and also the noble IrO2. The engineered material retains 100% of its original activity after operating at an overpotential of 350 mV for 100 h. A combination of theoretical calculations and experimental results finds out that the surface doped Fe promotes a high energy state and desired coordination environment in the near surface region, which enables optimized OER intermediates binding and favorably changes the rate-determining step.