MoS 2 Effect on Nickel Electrochemical Activation: An Atomistic/Experimental Approach

Abstract

Hybrid Ni-MoS2 electrocatalysts are one of the most promising materials for the generation of hydrogen in an alkaline medium. This paper presents a simple and economical method for the rational synthesis of Ni-MoS2 nanocomposites, maximizing the contact area and reducing the contact resistance between MoS2 and the nickel surface. In this way, it is possible to maximize the synergistic effect between both materials, obtaining a hybrid nanomaterial with high electroactivity toward the generation of hydrogen. A conventional nickel catalyst (NWts) was compared with the one obtained by dispersing a small amount of MoS2 (0.1425 μg cm-2) over the surface denoted as NMS, and with the same type of catalyst after a 10 s electrodeposition of Ni (NMSN), to have a Ni-MoS2-Ni laminar structure. Thus, the NMSN catalyst shows a current density value of 59% higher than the observed value on the NMS catalyst and 113% higher than that found in the conventional NWts catalyst. Finally, these results were analyzed using DFT theoretical studies. DFT calculations predict a charge transfer between MoS2 and nearby Ni atoms, which becomes more important when a second Ni layer is placed on MoS2 explaining the increase in catalytic activity in the NMSN catalyst. Furthermore, the high hydrophobicity of the MoS2 plays an important role in the electrochemically active surface when comparing NMS and NMSN catalysts.