Hierarchical flower-like CoS2-MoS2 heterostructure spheres as efficient bifunctional electrocatalyst for overall water splitting

Electrochemical water splitting technique requires high-efficient bifunctional electrocatalysts to obtain large-scale hydrogen production for resolving the impending energy and environmental crisis. Herein, hierarchical flower-like CoS2-MoS2 heterostructure hybrid spheres grown on carbon cloth (CoS2-MoS2/CC) were prepared by sulfuring wheel-shaped polyoxometalate {Co20Mo16}. The as-prepared CoS2-MoS2/CC as bifunctional electrocatalyst manifests excellent alkaline oxygen evolution and hydrogen evolution activities with low overpotentials of 240 mV for OER and 60 mV for HER at 10 mA cm−2, respectively. When assembled as two-electrode cell, CoS2-MoS2/CC delivers an extremely low cell-voltage of 1.52 V at 10 mA cm−2 accompanied with remarkable long-term durability. Additionally, CoS2-MoS2/CC exhibits favorable overall-water-splitting performance in simulated seawater. The superior performance of CoS2-MoS2/CC should be ascribed to the optimized intrinsic electron structure via electron transfer from MoS2 to CoS2 along with the synergistic effect of well-exposed heterostructure interfaces and favorable diffusion channels. This work offers a practical strategy for exploring high-efficient bifunctional electrocatalysts for overall water splitting.