Ag/La2O3/WO3 p–n heterojunction photocatalyst for clean environmental applications: degradation of oxytetracycline and H2 evaluation from formic acid

Abstract

In the present study, the photocatalytic activities of nanocrystalline new silver-based (Ag) tungsten oxide (WO3) and lanthanum oxide (La2O3) materials prepared using the simple precipitation synthesis technique are studied. As a result of characterizations, the activity of the materials in both photocatalytic hydrogen production and oxytetracycline degradation was investigated. The characterizations of the synthesized materials were made by scanning electron microscope, X-ray diffraction, Raman, UV–diffuse reflectance spectroscopy (UV–DRS), electrochemical properties and X-ray photoelectron spectroscopy analyses. Morphological analyses showed that the materials were in a spherical and polygonal form, and the peaks of the characteristic components were obtained in the structural analysis. In addition, the structures of the materials were elucidated by Raman analysis supported with the X-ray diffraction results. The oxidation values of the components were obtained and compared the other characterization techniques. UV–DRS spectra analysis observed a redshift in the absorbing band edge and lower bandgap energy with 2.94 and 2.56 eV for La2O3 and WO3, respectively. In the hydrogen production reaction from formic acid, the Ag/La2O3/WO3 sample showed a higher production yield than the others. The obtained H2 production yield is 130, 140 and 230 µmol g−1 h−1 for Ag/WO3, Ag/La2O3 and Ag/La2O3/WO3, respectively. In addition, similar results were obtained in the degradation of oxytetracycline. The original part of this study presents a new perspective on which an effective photocatalytic study can be done with this; that can be easily synthesized Ag/La2O3/WO3 and can also play a role in hydrogen production. © 2023, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.