Interface engineering assisted Fe-Ni3S2/Ni2P heterostructure as a high-performance bifunctional electrocatalyst for OER and HER

Rational development and construction of electrochemical water splitting catalysts with excellent activity and super-durability utilizing earth-abundant elements are extremely desirable and imperative for energy crisis. Herein, a self-supported hierarchical Fe-doped nickel sulfide/nickel phosphide (nanoflower-linked nanosheet arrays grown vertically on nickel foam) heterostructure electrocatalyst was obtained via a successive structural transformation to realize high-efficiency alkaline OER and HER performance. Benefiting from the novel nanoflower-sheet crosslinked structure on NF, electronic coupling reconstruction and abundant edge sites, as-synthesized Fe-Ni3S2/Ni2P electrocatalyst exhibits remarkable electrocatalytic OER and HER activity in both low and high current density regions. Specifically, the Fe-Ni3S2/Ni2P electrode achieved low overpotentials of 172, 277 and 357 mV at current densities of 10, 50 and 100 mA·cm−2 for OER, respectively. A series of experimental results confirmed that the surface reconfiguration behavior of Fe-Ni3S2/Ni2P heterostructure led to the formation of amorphous M-OH bond system, which was answerable to the prominent OER catalyst properties. This work confirms the potential of designing robust bifunctional electrocatalysts for alkaline water electrocatalysis by carefully combining doping engineering as well as interfacial effects.