C-scheme electron transfer mechanism: An efficient ternary heterojunction photocatalyst carbon quantum dots/Bi/BiOBr with full ohmic contact

Yuan Guan; Shaomang Wang; Qiongdie Du; Mingfei Wu; Zhiqian Zheng; Zhongyu Li; Shicheng Yan

doi:10.1016/j.jcis.2022.05.091

C-scheme electron transfer mechanism: An efficient ternary heterojunction photocatalyst carbon quantum dots/Bi/BiOBr with full ohmic contact

J Colloid Interface Sci. 2022 Oct 15:624:168-180. doi: 10.1016/j.jcis.2022.05.091. Epub 2022 May 20.

Authors

Yuan Guan¹, Shaomang Wang², Qiongdie Du¹, Mingfei Wu¹, Zhiqian Zheng³, Zhongyu Li⁴, Shicheng Yan⁵

Affiliations

¹ Jiangsu Province Key Laboratory of Fine Petrochemical Engineering, School of Petrochemical Engineering, Changzhou University, Changzhou, Jiangsu 213164, PR China.
² School of Environment and Safety Engineering, Changzhou University, Changzhou, Jiangsu 213164, PR China. Electronic address: gywsm@cczu.ed.cn.
³ School of Environment and Safety Engineering, Changzhou University, Changzhou, Jiangsu 213164, PR China.
⁴ Jiangsu Province Key Laboratory of Fine Petrochemical Engineering, School of Petrochemical Engineering, Changzhou University, Changzhou, Jiangsu 213164, PR China; School of Environment and Safety Engineering, Changzhou University, Changzhou, Jiangsu 213164, PR China. Electronic address: zhongyuli@cczu.edu.cn.
⁵ Eco-Materials and Renewable Energy Research Center (ERERC), College of Engineering and Applied Sciences, Nanjing University, No. 22 Hankou Road, Nanjing, Jiangsu 210093, PR China. Electronic address: yscfei@nju.edu.cn.

PMID: 35660886
DOI: 10.1016/j.jcis.2022.05.091

Abstract

With a facile one-pot solvothermal method, an efficient ternary heterojunction photocatalyst carbon quantum dots (CQDs)/Bi/BiOBr is firstly prepared. Ethylene glycol (EG) is used as the solvent and carbon source for the first time. At 190 °C for 3 h, while BiOBr is synthesized, EG is employed to prepare CQDs through bottom-up method. CQDs are grafted by a large number of functional groups with reducibility, which reduce some neighboring BiO⁺ to metal Bi. By modifying the solvothermal temperature and time, CQDs and Bi are in-situ controllably deposited on the surface of BiOBr microspheres. Due to different Fermi levels and work functions, the interfaces of CQDs, BiOBr and Bi are connected through ohmic junctions with low contact impedance. The hot electrons from Bi with surface plasmon resonance (SPR) properties, and electrons in the CB of BiOBr flow to CQDs, forming a C-scheme electron transfer mechanism. O₂^- from CQDs and h⁺ in the VB of BiOBr respectively attack the sites with higher and lower electron density in methyl orange (MO) molecule, resulting in its photodegradation into small molecular products.

Keywords: Bi; BiOBr; C-scheme photocatalyst; CQDs; Surface defects.