Facile synthesis of multifunctional zinc vanadate/polyaniline composite for photocatalytic degradation and supercapacitor applications

Abstract

Multifunctional Zn3V2O8/Polyaniline (ZnV/PANI) composite was prepared by in-situ oxidative polymerization method. The formation of ZnV and ZnV/PANI composite was proved by various characterization tools including such as FTIR, XRD, SEM, BET, VSM, TEM and XPS analysis. The average crystalline size calculated using Scherrer equation of ZnV and ZnV/PANI were found to be 45 nm and 92 nm respectively. From the Tauc plots the bandgap values (Eg) were found to be 2.4 eV and 2.0 eV for ZnV and ZnV/PANI respectively. The FE-SEM images clearly show the flakes incorporated cluster-like morphology. The BET surface area of ZnV and ZnV/PANI was found to be 22 m2 g−1 and 40 m2 g−1. The XPS results also confirm the successful formation of ZnV/PANI composite. The as-prepared samples were utilized as photocatalyst and electrode materials for energy applications. The ZnV/PANI composite showed an outstanding photocatalytic activity (94%) in the degradation of aqueous RhB dye under visible light irradiation. The optimum catalyst dosage for the degradation of 50 mL of 1 × 10−5 M RhB dye aqueous solution was 50 mg. The Langmuir-Hinselwood (L-H) kinetic model proves that the photodegradation mechanism follows pseudo-first order kinetics. Further, the supercapacitive behavior of the ZnV/PANI composite was tested using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) techniques in 1 M KOH electrolyte at the potential window of 0–0.55 V. ZnV/PANI electrode displayed a specific capacitance (Csp) of 664 F g−1 at 1 A/g. The satisfactory performance of ZnV/PANI composite is mainly ascribed to the synergistic effect of ZnV-PANI matrixes with the occurrence of multiple electroactive sites in the composite. The cycling stability test proved that ZnV/PANI electrode material retained 92% of its initial capacitance even after 6000 GCD cycles at 2 A/g. The finding of this study will help to determine the most efficient and cost-effective method for the removal of dyes from textile industry wastewater and also as an effective material for supercapacitor applications.