Phosphorization engineering ameliorated the electrocatalytic activity for overall water splitting on NiS nanosheets.

Phosphorization engineering is an alternative method to explore highly efficient electrocatalysts for water splitting. Herein, a heterostructure consisting of NiP and NiS supported on commercial nickel foam (NiS-NiP/NF) was prepared through the conversion of some NiS molecules into NiP by phosphorization engineering. Electrochemical tests revealed that the partial phosphorization of NiS effectively enhanced the catalytic activity of the host electrocatalyst towards the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M KOH; in particular, the NiS-NiP/NF electrode exhibited the current density of 50 mA cm at the very low OER overpotential of 287 mV and needed the low overpotential of 130 mV to afford 10 mA cm for the HER. Moreover, the alkaline electrolyzer assembled by two NiS-NiP/NF electrodes could deliver 10 mA cm at the low voltage of 1.58 V and exhibited excellent durability during electrolysis for 15 h. Therefore, our study opens up an attractive fabrication strategy for highly active heterostructure electrocatalysts.