Interface engineering of WS2/CoS2 heterostructure as a highly efficient electrode for hydrogen evolution reaction

Transition metal sulfides electrodes based heterogeneous nanostructures have attracted much attention to be used as electrocatalyst for hydrogen evolution reaction (HER). Herein, a nanosheet arrays WS₂/CoS₂ heterostructure grown on copper substrate as HER electrocatalyst with high density of active sites was fabricated by a facile one-step hydrothermal method. In comparison to pristine WS₂ and CoS₂ electrocatalysts, the WS₂/CoS₂ heterostructure showed a high HER activity with a small overpotential of 252 mV to achieve a current density of 10 mA cm^-2 in alkaline medium. Benefiting from the unique structure and synergetic effect between WS₂ and CoS₂, the resultant WS₂/CoS₂ electrocatalyst exhibits a large number of exposed heterointerfaces as highly abundant active sites, showing a fast charge transfer and a large electrochemical active surface area (ECSA: 52.75 cm²), which indicates a mutual relationship between interfacial engineering properties and electrocatalytic HER performance. Furthermore, the as-prepared WS₂/CoS₂ heterostructure retained its outstanding activity even after 1000 cycles, indicating excellent stability and notable durability toward HER. These fascinating characteristics via heterostructure engineering make the WS₂/CoS₂ electrocatalyst a remarkably effective and attractive candidate for future electrocatalytic hydrogen applications.