Novel hierarchical FeWO4–FeNi3 heterostructure nanosheets for highly active water electrolysis at large current density

The development of efficient bifunctional catalysts for water electrolysis is of great significance, especially at large current density. Herein, a kind of heterostructure catalyst composed of FeNi3 nanoparticles and FeWO4 nanosheets is prepared by hydrothermal and calcination. It exhibits good activity for both oxygen evolution reaction and hydrogen evolution reaction , only 1.43 V and −43 mV are needed to obtain ±10 mA cm−2 respectively. Besides, it can work for 100 h at 1000 mA cm−2 under simulated industrial condition (6.0 M KOH solution, 60 °C) for overall water splitting , showing robust stability. This good performance could owe to: (1) Heterostructure facilitates the electrons transfer at the interface, thereby promoting the reaction process and enhancing the intrinsic catalytic activity; (2) Hierarchical array structure consisting of nanoparticles and nanosheet can expose more active areas and accelerate the transport of ions and charges, accelerating the release of bubbles for enhancing stability. Therefore, this work offers a promising method to design high-performance catalyst for practical water electrolysis.