Ultrafast surface modification of FeS nanosheet arrays with Fe–Ni bimetallic hydroxides for efficient oxygen evolution

Abstract Designing and exploring efficient and stable Fe-based nanostructures catalyst is playing a critical role in the industrial application of water splitting. Herein, amorphous Fe–Ni bimetallic hydroxides film on the conductive FeS nanosheets supported by three-dimensional iron foam (IF) (denoted as FeNi(OH)x/FeS/IF) has been successfully synthesized by an ultrafast surface modification process (30 s). The fast surface reaction using FeS/IF as substrate in nickel nitrate solution facilitates the formation of bimetallic ultrathin film of FeNi(OH)x with enhanced performance oxygen evolution reaction (OER). Owing to the excellent conductivity, FeS nanosheets supported by IF may improve the dispersion and conductivity of FeNi(OH)x as active sites for OER. The physical characterizations confirm the closed interaction of FeNi(OH)x/FeS/IF, which suggests the validity of this facile surface modification. The electrochemical measurements show that FeNi(OH)x/FeS/IF only need a low overpotential of 273 mV to reach the 100 mA cm−2 (geometric current density) towards OER. The excellent catalytic performance can be attributed to the improved conductivity of substrate, a greater number of active sites and strong the synergistic effect of the Fe–Ni bimetallic hydroxides. The great long-term stability has been obtained. This work provides a simple route to produce advanced hierarchical nanostructure as electrocatalysts for OER.