Efficient photoelectrochemical water oxidation and electrochemical supercapacitor performance of ZnAl2O4 hexagonal microstructures

Abstract

ZnAl2O4 hexagonal microstructure (ZAO) was prepared using the co-precipitation assisted hydrothermal technique. The prepared ZAO exhibits a hexagon morphology. Optical properties study reveals the reduction of bandgap (3.05 eV) thank bulk ZAO materials. The photoelectrochemical (PEC) performance was significantly improved in the presence of light illumination and provides the photocurrent density of 1.32 mA/cm2 under the light-on conditions of linear sweep voltammetry (LSV) measurement. The ZAO materials provide very good photostability over the long period of time. A detailed analysis of the electrochemical supercapacitor performance of ZAO electrode materials was analyzed through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies. The ZAO electrode material shows the specific capacity of 255.4 mAh g−1 at the current density of 1A g−1. The ZAO electrode shows rate capability of ～67 % with cycle stability of 70 % at current density of 6 A g−1 over 500 cycles. The columbic efficiency of the electrode was found to be 98 % after 500 GCD cycles. According to the existing literature, this is the first report on ZAO's performance in supercapacitor applications and opens up new avenues for the exploration of other materials in ZAO - based materials for energy storage.