Rational design of selenium inserted 1T/2H mixed-phase molybdenum disulfide for energy storage and pollutant degradation applications.

MoS2based materials are recognized as the promising candidate for multifunctional applications due to its unique physicochemical properties. But presence of lower number of active sites, poor electrical conductivity, and less stability of 2H and 1T MoS2inherits its practical applications. Herein, we synthesized the Se inserted mixed-phase 2H/1T MoS2nanosheets with abundant defects sites to achieve improved overall electrochemical activity. Moreover, the chalcogen insertion induces the recombination of photogenerated excitons and enhances the life of carriers. The bifunctional energy storage and photocatalytic pollutant degradation studies of the prepare materials are carried out. Fabricated symmetric solid-state supercapacitor showed an exceptional capacitance of 178 mF cm-2with an excellent energy density of 8µWh cm-2and power density of 137 mW cm-2, with remarkable capacitance retention of 86.34% after successive 8000 charge-discharge cycles. The photocatalytic dye degradation experiments demonstrate that the prepared Se incorporated 1T/2H MoS2is a promising candidate for dye degradation applications. Further, the DFT studies confirmed that the Se inserted MoS2is a promising electrode material for supercapacitor applications with higherCQdue to a larger density of states near Fermi level as compared to pristine MoS2.

Two-Dimensional Layered Metallic VSe2 /SWCNTs/rGO Based Ternary Hybrid Materials for High Performance Energy Storage Applications.

In this work, the ternary hybrid structure VSe2 /SWCNTs/rGO is reported for supercapacitor applications. The ternary composite exhibits a high specific capacitance of 450 F g-1 in a symmetric cell configuration, with maximum energy density of 131.4 Wh kg-1 and power density of 27.49 kW kg-1 . The ternary hybrid also shows a cyclic stability of 91 % after 5000 cycles. Extensive density functional theory (DFT) simulations on the structure as well as on the electronic properties of the binary hybrid structure VSe2 /SWCNTs and the ternary hybrid structure VSe2 /SWCNTs/rGO have been carried out. Due to a synergic effect, there are enhanced density of states near the Fermi level and higher quantum capacitance for the hybrid ternary structure compared to VSe2 /SWCNTs, leading to higher energy and power density for VSe2 /SWCNTs/rGO, supporting our experimental observation. Computed diffusion energy barrier of electrolyte ions (K+ ) predicts that ions move faster in the ternary structure, providing higher charge storage performance.