Regulating electron density of NiFe-P nanosheets electrocatalysts by a trifle of Ru for high-efficient overall water splitting

Highly active and stable catalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is extremely important but challenging for overall water splitting. Herein, a strategy by modulating surface electron densities is adopted to design new catalyst: the Ru-NiFe-P nanosheets on 3D self-supported nickel foam was developed by doping a small quantity of Ru into transition metals phosphates. The designed catalyst displays excellent electrocatalytic performance in 1.0 M KOH, with low overpotentials of 44 mV at 10 mA cm−2 for HER and 242 mV at 100 mA cm−2 for OER. Particularly, it only needs 1.47 V to yield 10 mA cm−2 for overall water splitting. Density functional theory calculations reveal that Ru-incorporated NiFe-P can generate new active sites on Ru atoms and increase the catalytic activity of original P sites leading to an optimal Gibbs free-energy on catalysts surface. This work offers a new perspective for designing admirable electrocatalysts.