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/cm(2), 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. (C) 2019 Elsevier Inc. All rights reserved.