Tuning electronic property and surface reconstruction of amorphous iron borides via W-P co-doping for highly efficient oxygen evolution

Abstract

Designing cost-effective oxygen evolution reaction (OER) electrocatalysts is essential for sustainable water splitting. Recently, amorphous transition metal borides (TMBs) as OER pre-catalysts have acquired growing attention due to their favorable characteristics such as high conductivity, compositional and structural flexibility. Nevertheless, rational design of boride-based OER pre-catalysts remains an ongoing challenge. Herein, an efficient pre-catalyst derived from FeB with accelerated surface reconstruction and regulated intrinsic activity of evolved FeOOH is obtained by W and P co-doping. The obtained catalyst demonstrates an excellent OER activity with a low overpotential of 209 mV at a current density of 10 mA cm−2, and good stability in alkaline electrolyte, which surpasses most of boride-based OER catalysts. Specifically, the anion etching facilitates the surface reconstruction and accelerates the mass/charge transfer. Density functional theory calculations suggest W doping can enhance intrinsic catalytic activity via optimizing the adsorption free energy of reaction intermediates and improving the conductivity. Additionally, the hierarchical structure and amorphous feature also benefit the OER process. This study provides a fundamental insight into the correlation between surface structure and catalytic activity, and a powerful strategy to construct efficient OER pre-catalysts.