Synthesis of flower-like MoSe2@MoS2 nanocomposites as the high efficient water splitting electrocatalyst

•We synthesis the MoSe2@MoS2 core-shell nanostructure through a two-step growth procedure.•The introduction of MoSe2 results in the transformation of the MoS2 morphology from nanoparticles to nanoflower structures.•There is a strong electronic interaction between MoS2 and MoSe2.•The MoSe2@MoS2 nanocomposite exhibits enhanced catalytic performance compared with that of either single MoS2 or MoSe2.