Hierarchical MoSe2-CoSe2 nanotubes anchored on graphene nanosheets: A highly efficient and stable electrocatalyst for hydrogen evolution in alkaline medium

Hierarchical MoSe₂-CoSe₂ nanotubes anchored on graphene nanosheets (G/MS-CS NTs) are in-situ converted from the CoMoO₄ nanowires (NWs) and graphene oxide hybrid precursor via a facile hydrothermal method. As an electrocatalyst, G/MS-CS NTs show highly efficient and stable performance for hydrogen evolution reaction (HER) in alkaline medium. G/MS-CS NTs demonstrate superior HER performance with a very low onset overpotential of 109 mV vs. RHE, a low overpotential of 198 mV vs. RHE at −10 mA cm⁻², a small Tafel slope of 79 mV dec⁻¹, a large current density of 53.7 mA cm⁻² at −300 mV vs. RHE, and excellent long-term cycling stability. The outstanding HER activity of G/MS-CS NTs is attributed to its unique hierarchical structure with MS-CS NTs anchored on two-dimensional graphene nanosheets. The MS-CS NTs are well-constructed by few-layered MoSe₂ nanosheets and CoSe₂ nanoparticles with highly homogenous distribution, which can not only effectively suppress the aggregation of MoSe₂ nanosheets, but also generate more active sites or edges to enhance the electrocatalytic activity. In addition, the highly conductive graphene matrix can efficiently promote the electron transfer from the electrode to the active sites on MS-CS NTs during electrocatalytic process, further improving the HER performance.