Supercapacitor potentiality of tellurium selenide-gadolinium tungsten oxide composite material

Abstract

In this work, we used a hydrothermal route to synthesize tellurium selenide-gadolinium tungsten oxide material for supercapacitor application. Structural characterization by X-ray diffraction (XRD) revealed that the composite material consists of phases from the starting materials (i.e. Gd2(WO4)3 and Te0.39Se0.61). The composite material was amorphous up to annealing temperature of 700 °C but became crystalline at and beyond 800 °C. Energy dispersive spectroscopy (EDS) results confirmed that all the elements in Gd2(WO4)3 and Se0.61Te0.39 were present except selenium that was not detected in the composite material due to the possibility of overlap between rare earth elements (REE) with selenium. The band gap energy determined for Gd2(WO4)3 is 3.28 eV and after the incorporation of Te0.31Se0.61, it slightly increased to 3.39 eV for Gd2(WO4)3/Te0.39Se0.61. The electrochemical properties of all the materials indicated a quasi-reversible system and the current response was increasing with increasing scan rates indicating battery-type electrodes. The specific capacity obtained from GCD at a current density of 1.2 A g−1 were 64.3, 17.3 and 23.8 C g−1 for Gd2(WO4)3, Te0.39Se0.61 and Gd2(WO4)3/Te0.39Se0.61, respectively. Gd2(WO4)3 showed superior electrochemical performance compared to the composite however, the composite showed more pseudocapacitive nature.