The development of efficient materials for the generation and storage of renewable energy is now an urgent task for future energy demand. In this report, molybdenum disulphide hollow sphere (MoS2-HS) and its reduced graphene oxide hybrid (rGO/MoS2-S) have been synthesized and explored for energy generation and storage applications. The surface morphology, crystallinity and elemental composition of the as-synthesized materials have been thoroughly analysed. Inspired by the fascinating morphology of the MoS2-HS and rGO/MoS2-S materials, the electrochemical performance towards hydrogen evolution and supercapacitor has been demonstrated. The rGO/MoS2-S shows enhanced gravimetric capacitance values (318 ± 14 Fg−1) with higher specific energy/power outputs (44.1 ± 2.1 Whkg−1 and 159.16 ± 7.0 Wkg−1) and better cyclic performances (82 ± 0.95% even after 5000 cycles). Further, a prototype of the supercapacitor in a coin cell configuration has been fabricated and demonstrated towards powering a LED. The unique balance of exposed edge site and electrical conductivity of rGO/MoS2-S shows remarkably superior HER performances with lower onset over potential (0.16 ± 0.05 V), lower Tafel slope (75 ± 4 mVdec−1), higher exchange current density (0.072 ± 0.023 mAcm−2) and higher TOF (1.47 ± 0.085 s−1) values. The dual performance of the rGO/MoS2-S substantiates the promising application for hydrogen generation and supercapacitor application of interest.

No abstract

In this work, a rare VO2(D) phase plate-like structures and integrated with graphene [reduced graphene oxide (rGO)/VO2(D)] has been developed by facile hydrothermal route, explored their activity towards supercapacitor application and validated by the extensive ab initio simulations using density functional theory (DFT) study. After successful synthesis, the samples have been characterized by various techniques to know their crystal phase, surface morphology, and elemental composition. The energy storage performance of these electrode materials was studied by both symmetric and asymmetric supercapacitor devices. In a symmetric supercapacitor device, the hybrid material shows a high specific capacitance of 737 F g–1 at a scan rate of 1 mV s–1 and 244 F g–1 at a current density 1 A g–1 with an excellent cycle life of over 5000 cycles without any capacitance loss. Further, an asymmetric coin-cell supercapacitor device has been fabricated by using rGO as a negative electrode and the rGO/VO2(D) hybrid as a positive electrode. The energy storage performance was measured at a wide potential of 2 V, and the powering of a light-emitting diode has been demonstrated. The DFT simulations predict that the significant synergistic effect on enhanced capacitance can be attributed to orbital interactions and enhancement of electronic states near the Fermi level because of additional C 2p states from graphene.