Transition Metal Dichalcogenide Anchored in 3D Nickel Framework with Graphene Support for Efficient Electrocatalytic Hydrogen Evolution

Transition metal dichalcogenides (TMDCs), MoS2, and WS2 have emerged as low-cost and earth-abundant electrocatalysts for hydrogen evolution reaction (HER). In this work, electrocatalytic HER performance of these TMDCs, supported by few layered graphene and loaded on a 3D framework of Ni foam (Gr/NF), is reported. The graphene in Gr/NF is prepared from inexpensive camphor by atmospheric pressure chemical vapor deposition. The graphene-supported TMDCs anchored on the Ni foam are demonstrated with a low overpotential for HER below 200 mV at a current density of 10 mA cm(-2) which is comparable to their edge terminated counterparts and surpassing that of unsupported bulk or amorphous TMDCs. In addition, their small Tafel slopes (95 and 83 mV dec(-1) for MoS2- and WS2-based Gr/NF electrocatalysts, respectively), charge transfer resistance, and long-term stability make them promising non-noble electrocatalysts. First principle investigations of the (Mo/W)S-2/Gr/NF heterostructure shows that their enhanced electrocatalytic activity can be attributed to the d-band shift in the transition metals, Mo/W (a larger shift for WS2) by Ni, promoting unoccupied antibonding orbitals which facilitate the hydrogen adsorption-desorption process.