▎ 摘　　要

Porous 3D self-supported electrocatalysts have the advantages of being binder-free and facile gas transport within electrodes. In this work, metallic MoS2 nanosheets are vertically grown on graphene-protected Ni foam in situ. The free-standing feature of the metallic MoS2 nanosheets maximally exposes the active sites at both edges and the additional basal plane. The graphene deposited on Ni foam, on the other hand, enhances the acid resistant ability. As expected, the as-synthesized catalyst exhibits excellent catalytic activity for hydrogen evolution with a quite low overpotential of 117 mV at 10 mA cm(-2), a small Tafel slope of 38 mV per decade and excellent stability. This work will broaden the vision to improve the activity of self-supported electrocatalysts by polymorph engineering of anchored catalysts.