Synergistic effect of Co-Ni co-bridging with MoS nanosheets for enhanced electrocatalytic hydrogen evolution reactions.

The depletion of fossil fuels and associated environmental problems have drawn our attention to renewable energy resources in order to meet the global energy demand. Electrocatalytic hydrogen evolution has been considered a potential energy solution due of its high energy density and environment friendly technology. Herein, we have successfully synthesized a noble-metal-free Co-Ni/MoS nanocomposite for enhanced electrocatalytic hydrogen evolution. The nanocomposite has been well characterized using HRTEM, elemental mapping, XRD, and XPS analysis. The as-synthesized nanocomposite exhibits a much smaller onset potential and better current density than those of Co-MoS, Ni-MoS and MoS, with a Tafel value of 49 mV dec, which is comparable to that of a commercial Pt/C catalyst. The synergistic effect and interfacial interaction of Co-Ni bimetallic nanoparticles enhances the intrinsic modulation in the electronic structure resulting in an improved HER performance. Moreover, the electrochemical impedance spectroscopic results suggest smaller resistance values for the Co-Ni/MoS nanocomposite, compared to those for the charge transfer of bare nanosheets, which increase the faradaic process and in turn enhance the HER kinetics for a better performance. Our as-synthesized Co-Ni/MoS nanocomposite holds great potential for the future synthesis of noble-metal-free catalysts.