Ultrathin FeP Nanosheets as an Efficient Catalyst for Electrocatalytic Water Oxidation: Promoted Intermediates Adsorption by Surface Defects

The slow kinetics of oxygen evolution reaction (OER) catalysts with a large overpotential restricts the feasibility of electrochemical water splitting. Iron based electrodes are attractive candidates, but elevating their activity faces great challenges in weak intermediate adsorption. Herein, we demonstrated that ultrathin FeP nanosheets with Fe defects on nickel foam (FeP-NS/NF) exhibited a remarkable electrocatalytic oxygen evolution performance. The overpotential of FeP-NS/NF only requires 220 mV to achieve a current density of 10 mA cm(-2) in 1 M KOH solution. Moreover, it possessed excellent durability during the 85 h stability test. Fe defects over ultrathin FeP evidenced by X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) have been experimentally demonstrated to promote oxygenated intermediate adsorption, which largely reduce the overpotential of OER.