Strobilanthes crispus (B.) leaf extract-assisted green synthesis of ZnO-La2O3 composite and preliminary study of its photocatalytic activity

Abstract

In this study, ZnO-La2O3 composite as photocatalyst was synthesized via facile sol-gel route using biomaterial as a weak base source and a capping agent. ZnO-La2O3 composite was successfully formed through the reaction of Zn(NO3)2 (aq), La(NO3)3 (aq) and Strobilanthes crispus (B.) aqueous leaf extract. Zn-O and La-O vibration modes of ZnO-La2O3 composite was analysed by Fourier Transform Infra Red (FTIR) at 400-700 cm-1 wavenumber. Optical band gap of ZnO-La2O3 composite determined by using Tauc plot method was about 5.21 eV. X-Ray Diffraction (XRD) pattern of ZnO-La2O3 composite confirmed a combination of the diffraction patterns of ZnO particle and La2O3 particle. Photocatalytic activity of ZnO-La2O3 composite and ZnO particle were observed with methylene blue using UV light irradiation. The percentage of methylene blue degradation using ZnO-La2O3 composite and ZnO particle were 81.75 % and 74.87 %, respectively. This result shows that La2O3 was improving the activity and stability of the ZnO photocatalyst.