Three-dimensional structure of WS2/graphene/Ni as a binder-free electrocatalytic electrode for highly effective and stable hydrogen evolution reaction

Abstract

Tungsten disulfide (WS2) has attracted much attention as the promising electrocatalyst for hydrogen evolution reaction (HER). Herein, the three-dimensional (3D) structure electrode composed of WS2 and graphene/Ni foam has been demonstrated as the binder-free electrode for highly effective and stable HER. The overpotential of 3D WS2/graphene/Ni is 87 mV at 10 mA cm−2, and the current density is 119.1 mA cm−2 at 250 mV overpotential, indicating very high HER activity. Moreover, the current density of 3D WS2/graphene/Ni at 250 mV only decreases from 119.1 to 110.1 mA cm−2 even after 3000 cycles, indicating a good stability. The high HER performance of 3D WS2/graphene/Ni binder-free electrode is superior than mostly previously reported WS2-based catalysts, which is attributed to the unique graphene-based porous and conductive 3D structure, the high loading of WS2 catalysts and the robust contact between WS2 and 3D graphene/Ni backbones. This work is expected to be beneficial to the fundamental understanding of both the electrocatalytic mechanisms and, more significantly, the potential applications in hydrogen economy for WS2.