MoS₂ Effect on Nickel Electrochemical Activation: An Atomistic/Experimental Approach

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.