Hexagonal cage like structured reduced graphene Oxide-NiCo2S4 nanocomposite for high performance hydrogen evolution reaction.

In the present study, a facile and simple hydrothermal technique was employed for the preparation of reduced graphene oxide (rGO) incorporated NiCo 2 S 4 and analyzed the hydrogen evolution reaction (HER) activity in alkaline media. The face centered cubic crystal structure is confirmed from the X-ray diffraction analysis and hexagonal cage like structure of NiCo 2 S 4 was visualized by FESEM analysis. With the increased number of facets in hexagonal cage structure, the electrochemical-active surface area (ECSA) gets increased, and the HER performance gets increased for bare NiCo 2 S 4. The additional ECSA is caused by the existence of rGO in the case of ternary nanocomposite (rGO-NiCo 2 S 4). The obtained small over potential (370 mV) and small Tafel slope (139 mV/dec) proves the excellent HER activity of rGO-NiCo 2 S 4 nanocomposite. The optimized rGO-NiCo 2 S 4 as excellent HER electrocatalyst provides a highly stable polarization curve up to 10 h and it can be more useful to replace the high-cost platinum noble electrocatalyst. [Display omitted] • A simple one step hydrothermal method was adopted to prepare pure and rGO incorporated NiCo 2 S 4. • A hexagonal cage like structure provides the large number of facet as well as high electrochemical-active surface area. • A small over potential of 370 mV and a small Tafel slope of 139 mV/dec was realized at 10 mA/cm2. [ABSTRACT FROM AUTHOR]