Structural, optical, Raman characteristics of C-nanospheres incorporated Gd2O3:SeO2 nanoclusters for energy storage applications

Abstract

In the present work, novel nanocrystals (NCs) of carbon nanospheres (Cx) (5%, 10%, and 15%) anchored on Gd3+:SeO2 (Cx:Gd3+@SeO2) were synthesized and characterized by XRD (x-ray diffraction), SEM (scanning electron microscopy), SEM-energy dispersive x-ray, UV-visible, x-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, and Raman analytical techniques. XRD analysis showed that the synthesized Cx:Gd3+@SeO2 NCs exhibit mixed tetragonal phase. Gd3+@SeO2 NCs transformed into irregular flake-like morphology with increasing percentage of Cx. Optical property studies showed the presence of Cx in Gd3+@SeO2 NCs matrix leads to tuning of bandgap (Eg). Incorporation of Cx leads to decrease in the bandgap from 3.64 to 3.58 eV. XPS investigation revealed chemical composition and valence state of Cx:Gd3+@SeO2 NCs. Carbon-based materials, especially, carbon nanospheres, have attracted much attention due to their good conductivity, low cost, high surface area, porosity, etc. Upon doping Cx, the conducting network of the Gd3+@SeO2 lattice is improvised, which forms hollow structures and facilitates penetration of the electrolyte. Raman studies confirmed the formation of Gd-O-Gd/Gd2O3, Se-O-Se/SeO2, and C-H (D and G) fringes. Supercapacitor properties of Cx:Gd3+@SeO2 NCs investigated in 3M KOH solution using three electrode system showed specific capacitance of 239.4 F/g at current density of 0.5 A/g with 89% capacitance retention over 3000 cycles. The synthesized nanocrystals can be used as potential candidates for optical devices and battery applications.