In situ synthesis of hierarchical MoSe2–CoSe2 nanotubes as an efficient electrocatalyst for the hydrogen evolution reaction in both acidic and alkaline media

Abstract

Hierarchical MoSe₂–CoSe₂ nanotubes (MS–CS NTs) are in situ converted from the CoMoO₄ nanowires (NWs) via a facile hydrothermal selenization method. As an electrocatalyst, MS–CS NTs show highly efficient and stable performance for the hydrogen evolution reaction (HER). In acidic (or alkaline) medium, MS–CS NTs demonstrate superior HER performance with a very low onset overpotential of 148 (or 127) mV vs. RHE, a low overpotential of 206 (or 237) mV vs. RHE at −10 mA cm⁻², a very large current density of 84.6 (or 23.5) mA cm⁻² at −300 mV (vs. RHE), a small Tafel slope of 45 (or 89) mV dec⁻¹ and remarkable long-term cycling stability. The outstanding HER activity of MS–CS NTs in both media is attributed to their unique hierarchical and nanoporous architecture constructed with the homogeneous distribution of few-layered MoSe₂ nanosheets and CoSe₂ nanoparticles, which can not only efficaciously suppress the aggregation of MoSe₂ nanosheets, but also generate more active sites or edges to take part in the HER. In addition, the uniform dispersion of highly conductive CoSe₂ nanoparticles in few-layered MoSe₂ nanosheets efficiently promotes the electron transfer from the electrode to the active sites on MoSe₂ nanosheets, further improving the electrocatalytic properties.