Heterostructured MoS₂@Bi₂Se₃ nanoflowers: A highly efficient electrocatalyst for hydrogen evolution

The transition metal dichalcogenide MoS₂ shows good catalytic properties for the hydrogen evolution reaction (HER). However, the HER activity of 2D MoS₂ is limited by its poor electrical conductivity. Bi₂Se₃ nanosheets are topological insulators possessing metallic surface states, thereby displaying unconventional electron dynamics and excellent conductivity. Therefore, combining Bi₂Se₃ nanosheets and with MoS₂ nanosheets represents a rational approach for improving the HER activity of MoS₂. In this work, Bi₂Se₃ nanoflowers were first synthesized via a hot injection method, followed by the slow growth of MoS₂ nanosheets on their surface to form heterostructured MoS₂@Bi₂Se₃ nanoflowers. Compared to pristine Bi₂Se₃ and MoS₂, the MoS₂@Bi₂Se₃ nanoflowers exhibited outstanding HER activity in acidic media with an onset overpotential of 134 mV, an overpotential of 208 mV at 10 mA/cm², a Tafel slope of 57 mV/dec and remarkable stability. The enhanced HER catalytic activity offered by the MoS₂@Bi₂Se₃ nanoflowers is attributed excellent electron transfer from Bi₂Se₃ to MoS₂, as well as the abundance of edge-rich MoS₂ nanosheets vertically aligned on the Bi₂Se₃ support that act as H₂ evolution sites.