Interface-engineered MoS2/CoS/NF bifunctional catalysts for highly-efficient water electrolysis

The utilization of non-noble metal catalysts with robust and highly efficient electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are extremely important for the large-scale implementation of renewable energy devices. Integration of bifunctional electrocatalysts on both anode and cathode electrodes remains a significant challenge. Herein, we report on a novel and facile strategy to construct the ordered and aligned MoS2 nanosheet-encapsulated metal–organic frameworks (MOFs) derived hollow CoS polyhedron, in-situ grown on a nickel foam (NF). The starfish-like MoS2/CoS/NF heterojunctions were formed due to the ordered growth of the material caused by NF substrate. The optimized 2-MoS2/CoS/NF heterojunction exhibits robust bifunctional electrocatalytic activity with a low overpotential of 67 and 207 mV toward the HER and OER at 10 mA cm−2, and the long-term stability, which exceeds most of the reported bifunctional electrocatalysts. Such high electrocatalytic performance arises due to the synergistic effect between the MoS2 and CoS phases across the interface, the abundant active sites, as well as the hierarchical pore framework, which collectively enhance the mass and electron transfer during the reactions. The work provides a promising approach to fabricating bifunctional catalysts with custom-designed heterojunctions and remarkable performance for applications in electrochemical energy devices and related areas.