Carbon quantum dots-TiO2 nanocomposite as an efficient photocatalyst for the photodegradation of aromatic ring-containing mixed VOCs: An experimental and DFT studies of adsorption and electronic structure of the interface

Asad Mahmood; Gansheng Shi; Zhuang Wang; Zepeng Rao; Wang Xiao; Xiaofeng Xie; Jing Sun

doi:10.1016/j.jhazmat.2020.123402

Carbon quantum dots-TiO₂ nanocomposite as an efficient photocatalyst for the photodegradation of aromatic ring-containing mixed VOCs: An experimental and DFT studies of adsorption and electronic structure of the interface

J Hazard Mater. 2021 Jan 5:401:123402. doi: 10.1016/j.jhazmat.2020.123402. Epub 2020 Jul 8.

Authors

Asad Mahmood¹, Gansheng Shi², Zhuang Wang², Zepeng Rao², Wang Xiao², Xiaofeng Xie², Jing Sun³

Affiliations

¹ Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China. Electronic address: amkhan036@yahoo.com.
² Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China.
³ Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China. Electronic address: jingsun@mail.sic.ac.cn.

PMID: 32763698
DOI: 10.1016/j.jhazmat.2020.123402

Abstract

In this work, we have developed and optimized TiO₂ nanoparticles decorated with carbon quantum dots to examine its potential use in the photocatalytic oxidation of aromatic ring containing gas-phase mixed volatile organic compounds, e.g., benzene, toluene, and p-xylene. Carbon quantum dots decorated TiO₂ demonstrated good photodegradation efficiency in contrast to pure TiO₂ under UV-vis light illumination. For example, with 0.5 wt% carbon quantum dots decorated on TiO₂, 64 % of the mixed volatile organic compounds were photodegraded, while pure TiO₂ only exhibited 44 % of the photodegradation efficiency. Also, the carbon quantum dots (0.5 wt%)/TiO₂ nanocomposite demonstrated considerable photocatalytic activity within the visible region. On the other hand, pure TiO₂ remained inactive within the visible region. The density functional theory study of the carbon quantum dots/TiO₂ interface revealed that C 2p states of carbon quantum dots incorporated new energy states around the Fermi level near the lowest conduction band. This might be accountable for the improved charge separation process and better conductivity of the photogenerated electrons. The improved photocatalytic performance of the carbon quantum dots/TiO₂ nanocomposites can be attributed to good light harvesting within the UV-vis region, charge separation, and adsorption capability.

Keywords: Carbon quantum dots; Oxide semiconductor materials; Photocatalytic oxidation; Volatile organic compounds.