Hollow Mo-doped NiSx nanoarrays decorated with NiFe layered double-hydroxides for efficient and stable overall water splitting

Abstract

Rationally designed highly active and robust electrocatalysts toward overall water splitting through multi-compositional regulation and architectural engineering are very significant for efficient hydrogen production. Herein, a three-dimensional (3D) hollow core–shell hybrid material is fabricated by electrodepositing NiFe LDH nanosheets on Mo-doped NiS_x nanoarrays (Mo-NiS_x@NiFe LDH/NF). Owing to the numerous exposed active sites and favorable mass transfer, the optimized Mo-NiS_x@NiFe LDH/NF requires low overpotentials to deliver 10 mA cm⁻² for the OER (224 mV) and HER (61.3 mV). Importantly, the alkali-electrolyzer assembled by Mo-NiS_x@NiFe-LDH/NF displays an applied voltage of 1.54 V at 10 mA cm⁻² and operates stably over 72 h at 200 mA cm⁻², better than most previously reported counterparts. The density functional theory (DFT) calculations disclose that Mo-doping effectively lowers the reaction energy barrier, resulting in outstanding HER performance, while the electron regulation caused by Ni and Fe anchoring boosts the interaction of electrons and promotes the desorption of O₂, thus reducing the reaction energy barrier of the OER process. This work showcases a successful prototype with multi-compositional regulation and architectural engineering for preparing superior electrocatalysts for overall water splitting.