Mechanistic insight into the charge carrier separation and molecular oxygen activation of manganese doping BiOBr hollow microspheres

• Published in: Journal of colloid and interface science Vol. 629; no. Pt A; pp. 355 - 367
• Main Authors: He, Zuming, Fareed, Hasan, Yang, Hanpei, Xia, Yongmei, Su, Jiangbin, Wang, Lina, Kang, Li, Wu, Mi, Huang, Zhengyi
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.2023
• Subjects: Charges separation; gentian violet; manganese; microparticles; Mn-doping; oxygen; Oxygen activation; Oxygen vacancies; photocatalysis; photocatalysts; Synergistic mechanism; Charges separation; Oxygen vacancies; Oxygen activation; Synergistic mechanism; Mn-doping
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2022.08.164

Photocatalytic process of Bi0.8Mn0.2OBr for CV degradation. [Display omitted] •The Mn-doping BiOBr generated intermediate state in band gap.•Oxygen vacancies and Mn-doping synergistic ameliorating separation of the photo-generated charge.•The intermediate energy states and oxygen vacancies play important role in charge separation.•DFT calculation confirmed the oxygen vacancies beneficial to molecular oxygen activation.•The in-depth mechanisms insight of charge separation and molecular oxygen activation. High-efficiency separation of photogenerated charges and molecular oxygen activation is very important for photocatalytic removal of organic pollutants. However, the current understanding of the effect mechanism of metal substitution for the separation of photo-generated charges and molecular oxygen activation is still poor. Herein, efficient manganese (Mn)-doped BiOBr hollow microspheres synthesis, systematic characterizations, and theoretical calculation discovered that Mn-doping could not only induce produce oxygen vacancies (OVs), but also can act as active sites for catalytic reactions. The induced production of OVs and Mn2+/Mn3+ by Mn optimal doping introduced into BiOBr can synergistic promote the separation of photogenerated charges and molecular oxygen activation leads to significantly enhances degradation of crystal violet (CV). Upon analysis, Mn-doping introducing unsaturated d-orbital with bridging O2– formation π-donation accelerated the separation of photo-generated charges. Meanwhile, the larger overlap of Mn-3d orbitals with O2-2p orbitals forms a π-donation bond with charge transfer from metal to O2 leading to the oxygen–oxygen (OO) bond length and molecular oxygen activation. Finally, we proposed a possible mechanism to explain the highly efficient photocatalytic degradation performance of the acquired photocatalysts. This study provides not only a novel strategy for the rational design of highly active photocatalysts, but also in-depth insights into the separation of photo-generated charges and molecular oxygen activation.