Interfacial engineering of heterostructured carbon-supported molybdenum cobalt sulfides for efficient overall water splitting

Constructing hetero-structured catalyst is promising but still challenging to achieve overall water splitting for hydrogen production with high efficiency. Herein, we developed a sulfide-based MoS₂/Co_1−xS@C hetero-structure for highly efficient electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The carbon derived from the filter paper acts as a conducting carrier to ensure adequate exposure of the active sites guaranteed with improved catalytic stability. The unique hierarchical nano-sheets facilitate the charge and ion transfer by shortening the diffusion path during electro-catalysis. Meanwhile, the robust hetero-interfaces in MoS₂/Co_1−xS@C can expose rich electrochemical active sites and facilitate the charge transfer, which further cooperates synergistically toward electro-catalytic reactions. Consequently, the optimal MoS₂/Co_1−xS@C hetero-structures present small over-potentials toward HER (135 mV @ 10 mA·cm⁻²) and OER (230 mV @ 10 mA·cm⁻²). The MoS₂/Co_1−xS@C electrolyzer requires an ultralow voltage of 1.6 V at the current density of 10 mA·cm⁻² with excellent durability, outperforming the state-of-the-art electro-catalysts. This work sheds light on the design of the hetero-structured catalysts with interfacial engineering toward large-scale water splitting.