Surface engineering of superhydrophilic Ni2P@NiFe LDH heterostructure toward efficient water splitting electrocatalysis

Abstract

Building heterostructures with rich interfaces by surface engineering is one of the most promising approaches to integrating the rich functionalities for water splitting. Herein, the porous and superhydrophilic nickel phosphide@ NiFe bimetal layered double hydroxides (NF-Ni2P@NiFe LDH) heterostructure in situ grown on nickel foam was successfully constructed. As a result, the unique of self-supported heterostructure and superhydrophilic surface facilitated electron and mass transfer. In addition, the porous structure promoted active site exposure and was in favor of bubble release. Benefiting from the aforementioned advantages, the NF-Ni2P@NiFe LDH performed a superior catalytic performance for water splitting, with a low overpotential of 105.4 mV for hydrogen evolution reaction (HER) and 203.5 mV for oxygen evolution reaction (OER) at 10 mA cm−2, thus a battery voltage of just 1.53 V providing a current density of 10 mA cm−2 at a two-electrode electrolytic cell. Furthermore, the NF-Ni2P@NiFe LDH showed a remarkable stability, which worked for over 60 h at 100 mA cm−2 without visible delay. The ex-situ Raman revealed that the NiOOH and FeOOH severed as active site for OER and HER, respectively.