Fe-doping engineering of hierarchical NiS/Co2.67S4 nanoarrays as bifunctional electrocatalysts toward high-efficiency overall water splitting

Transition metal sulfides (TMS) have emerged as promising electrocatalysts for overall water splitting (OWS), owing to their cost-effectiveness, inherent abundant active sites and tunable electronic structures. However, several issues, e.g. , high overpotentials originating from the sluggish water dissociation, shielding of active sites and mass transfer resistance, as well as the modest long-duration electrocatalytic stability, are still enormous challenges. For this, the superwetting leafy Fe-doped nickel sulfide/cobalt sulfide nanoarrays on nickel foam (NF) (denoted as Fe-NiS/Co 2.67 S 4 /NF) are successfully designed and fabricated by the template-involved avenue. The interfacial electron re-arrangement of NiS/Co 2.67 S 4 induced by Fe doping optimizes the charge density distribution near the d-band center, promoting the adsorption-desorption of reaction intermediates. Additionally, the unique leafy architecture exhibits superhydrophilic sur−/interfaces, enabling efficient electrolyte penetration and accelerated bubble release during in-situ gas generation. Thereby, the advantages validated by comprehensive physical experiments and theoretical calculations endow Fe-NiS/Co 2.67 S 4 /NF with superior electrocatalytic performance in both hydrogen evolution reaction and oxygen evolution reaction, along with remarkable operational stability during high-current-density overall water electrolysis (1000 h at 500 mA cm −2 ). This work, besides the well-established reliable methodology for TMS nanoarrays, offers in-depth insights into catalytic optimization of electrocatalysts for high-efficiency OWS.