Hierarchical Metal Sulfides Heterostructure as Superior Bifunctional Electrode for Overall Water Splitting.

The development of highly active bifunctional electrocatalysts for overall water splitting is of significant importance, but huge challenges remain. The key element depends on engineering the electronic structure and surface properties of material to achieve improved catalytic activity. Herein, a hierarchical nanowire array of metal sulfides heterostructure on nickel foam (FeCoNiS x /NF) was designed as a novel type of hybrid electrocatalyst for overall water splitting. The hybrid structure endowed plenty of catalytic active sites, strong electronic interactions, and high interfacial charge transferability, leading to superior bifunctional performance. As a result, the FeCoNiS x /NF catalyst delivered low overpotentials of 97 and 260 mV at the current density of 50 mA cm -2 for hydrogen and oxygen evolution reactions, respectively. Moreover, the FeCoNiS x /NF-based water electrolyzer exhibited a small potential of 1.57 V for a high current density of 50 mA cm -2 . These results indicate the promising application potential of FeCoNiS x /NF electrode for hydrogen generation. This work provides a new approach to develop robust hybrid materials as the highly active electrode for electrocatalytic water splitting.