A promising Ag2CrO4/LaFeO3 heterojunction photocatalyst applied to photo-Fenton degradation of RhB

• Published in: Environmental technology Vol. 41; no. 12; pp. 1486 - 1503
• Main Authors: Ye, Yongchun, Yang, Hua, Zhang, Haimin, Jiang, Jinling
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 24-05-2020; Taylor & Francis Ltd
• Subjects: Charge density; Charge transfer; Chemical precipitation; Chromates; Composite materials; CrO; Degradation; dye degradation; Ferrites; Free radicals; heterojunction; Heterojunctions; Hydrogen peroxide; LaFeO; Lanthanum compounds; Light sources; Nanoparticles; photo-Fenton performance; Photocatalysis; Photocatalysts; Photoelectric effect; Photoelectric emission; Silver compounds; Spectroscopy; synergistic effect; X ray photoelectron spectroscopy
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2018.1538261

Ag
2
CrO
4
nanoparticles (10-35 nm) were assembled onto LaFeO
3
nanoparticles (20-60 nm) via a facile chemical precipitation method to form novel Ag
2
CrO
4
-LaFeO
3
heterojunction composite photocatalysts. The prepared Ag
2
CrO
4
-LaFeO
3
composites were characterized by XRD, SEM, TEM, XPS, BET, UV-vis DRS, PL spectroscopy and EIS and photocurrent response. The TEM result clearly shows that Ag
2
CrO
4
particles are decorated onto LaFeO
3
particles to form Ag
2
CrO
4
-LaFeO
3
heterojunction. Compared to bare LaFeO
3
, the 10%Ag
2
CrO
4
-LaFeO
3
composite exhibits a slightly increased BET specific surface area, increased photocurrent density, decreased charge-transfer resistance and decreased PL emission peaks. Using simulated sunlight as the light source and in the presence of H
2
O
2
, the photo-Fenton performance of the composite photocatalysts toward the degradation of RhB was investigated, revealing that they manifest significantly enhanced photo-Fenton degradation of RhB when compared with bare LaFeO
3
and Ag
2
CrO
4
. Among the composite photocatalysts, 10%Ag
2
CrO
4
-LaFeO
3
exhibits the highest photo-Fenton activity, which is about 3.1 and 2.5 times higher than that of bare LaFeO
3
and Ag
2
CrO
4
, respectively. This is attributed to the fact that the composite photocatalysts have highly efficient separation of photogenerated electron-hole pairs due to the formation of Ag
2
CrO
4
-LaFeO
3
heterojunctions. Active species trapping experiments and ·OH detection experiments were carried out, from which it is concluded that ·OH radicals are the dominant reactive species causing the dye degradation. A synergistic mechanism was proposed to elucidate the enhanced photo-Fenton activity of Ag
2
CrO
4
-LaFeO
3
heterojunction composites.