Construction of β-Bi 2 O 3 /Bi 2 O 2 CO 3 heterojunction photocatalyst for deep understanding the importance of separation efficiency and valence band position

• Published in: Journal of hazardous materials 2021-01, Vol.401, p.123262
• Main Authors: Li, Jie-Hao, Ren, Jie, Hao, Ying-Juan, Zhou, Er-Peng, Wang, Yue, Wang, Xiao-Jing, Su, Ran, Liu, Ying, Qi, Xue-Han, Li, Fa-Tang
• Format: Article
• Language: English
• ISSN: 1873-3336

Constructing heterojunctions would result in the change of valence band position, which is an important factor determining the oxidative ability of photo-induced holes, has received scant attention. In this paper, β-Bi O /Bi O CO composites with different ratios were obtained via ionic-liquid-assisted solvothermal and in-situ calcination processes. UV-vis DRS, Mott-Schottky test, and Kelvin probe measurement showed the change of band gaps of β-Bi O and Bi O CO before and after heterojunction formation. SPV, ESR, photocurrent, and scavenger experiments identified the separation efficiency of photo-generated electrons and holes, as well as the active species generated in the photocatalytic process. The photocatalytic mechanism was investigated by the degradation of Rhodamine B (RhB) upon visible-light and simulated sunlight, respectively. The results demonstrated that β-Bi O /Bi O CO heterojunctions possessed enhanced separation efficiency and higher degradation ability than the individuals under visible-light irradiation due to effective electron transfer. However, lower performance under simulated sunlight was observed, although their separation efficiency remained high. The decisive reason for this was that the up-shift of valence band of Bi O CO induced by hybridization and the transition of holes from VB of Bi O CO to that of β-Bi O with more negative potential decreased the oxidative ability of holes, which surpassed the positive influence of enhanced separation efficiency.