Facile Hydrothermal Synthesis of Zn3-xCoxV2O8 Nanomaterials for the Applications in Photocatalysis and Supercapacitors

Abstract

In this new era, with fast expansion of present civilization along with the progression of industrial development, environmental pollution and extreme exhaustion of energy sources has become crucial problem. Firstly, environmental pollution (including water and air) is the most critical problem at present day, thus the degradation of organic and toxic pollutants in solution or in air by photocatalysis has become an effective practice to cure effect of environmental pollution. Secondly, conservative fossil fuels at are near exhaustion. Thus, it is really important to introduce diverse energy sources. Here, in this work, we report various metal vanadate based oxides (Zn3V2O8, Co3V2O8 and their composites) for the photocatalytic degradation of methylene blue, which is a major industrial waste and pollution causing agent and energy storage device supercapacitor. Characterization of synthesized nanomaterials was further done by various techniques including powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) and UV-Visible diffused reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and Cyclovoltametry (CV).These techniques have confirmed that nanoparticles and their nanocomposites have been synthesized successfully. Among different synthesized photocatalysts, it was expected that nanocomposites would show better photocatalytic and electrochemical properties as compared to their individual counter parts. The nanomaterials and their composites were synthesized through a simplistic one pot hydrothermal method. The electrochemical supercapacitor performance of the Zn3V2O8 nanoplatelets, Co3V2O8 nanoparticles and their composites were studied by using cyclic voltammetry along with the galvanostatic charge-discharge studies. The shapes of the CV curves indicate that the capacitance is mainly due to the pseudocapacitance as the CV curves do not tell about electric double layer capacitance. Further specific capacitance and cyclic stability was evaluated using galvanostatic charge discharge curve analysis at various current densities. All the curves show pseudocapacitive effect because the curve shows a little deviation from isosceles triangular shape.