Electronic Structure Regulation of Nickel Phosphide for Efficient Overall Water Splitting.

Rational design and fabrication of efficient and low-cost catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are crucial for hydrogen production from water electrolysis. Herein, we report heteroatom Fe-incorporated Ni5P4 (Fe-NiP) as an excellent bifunctional catalyst for overall water splitting. Density functional theory (DFT) calculations reveal that heteroatom Fe effectively steers the electronic structure of Ni5P4, which optimizes the hydrogen adsorption behavior. Additionally, the hierarchical conductive framework of Fe-NiP contributes to abundant active sites. Thus, the Fe-NiP catalyst shows robust performance with enhanced intrinsic catalytic activity. As a good bifunctional catalyst, it demands low overpotentials of 144 and 223 mV to deliver a current density of 10 mA cm-2 for HER and OER, respectively. Considering the good bifunctional activity, an outstanding electrolyzer has been successfully assembled, which is superior to the benchmark of a RuO2(+)//Pt/C(-) electrolyzer. This study sheds light on steering the electronic structure of electrocatalysts through a heteroatom modulation strategy.