Facile Vacuum Annealing-Induced Modification of TiO2 with an Enhanced Photocatalytic Performance

Zhenpeng Cui; Min Zhao; Xueyan Que; Jingjing Wang; Yang Xu; Mohamed Nawfal Ghazzal; Christophe Colbeau-Justin; Duoqiang Pan; Wangsuo Wu

doi:10.1021/acsomega.1c03762

Facile Vacuum Annealing-Induced Modification of TiO₂ with an Enhanced Photocatalytic Performance

ACS Omega. 2021 Sep 28;6(41):27121-27128. doi: 10.1021/acsomega.1c03762. eCollection 2021 Oct 19.

Authors

Zhenpeng Cui^{1

2}, Min Zhao², Xueyan Que³, Jingjing Wang², Yang Xu², Mohamed Nawfal Ghazzal⁴, Christophe Colbeau-Justin⁴, Duoqiang Pan^{1

2}, Wangsuo Wu^{1

2}

Affiliations

¹ Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou 730000, China.
² School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China.
³ College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
⁴ Institue de Chimie Physique, UMR 8000 CNRS, Université Paris-Saclay, Orsay 91405, France.

Abstract

In this work, the photocatalytic performance enhancement of hydrothermally prepared TiO₂ was achieved by facile vacuum annealing treatment. Calcination of TiO₂ powder in air (CA-TiO₂) maintained its white color, while gray powder was obtained when the annealing was performed under vacuum (CV-TiO₂). Fourier transform infrared, total organic carbon, X-ray photoelectron spectroscopy, and electron paramagnetic resonance analyses proved that vacuum annealing transformed ethanol adsorbed on the surface of TiO₂ into carbon-related species accompanied by the formation of surface oxygen vacancies (Vo). The residual carbon-related species on the surface of CV-TiO₂ favored its adsorption of organic dyes. Compared with TiO₂ and CA-TiO₂, CV-TiO₂ exhibited an improved charge carrier separation with surface Vo as trapping sites for electrons. Vacuum annealing-induced improvement of crystallinity, enhancement of adsorption capacity, and formation of surface Vo contributed to the excellent photocatalytic activity of CV-TiO₂, which was superior to that of commercial TiO₂ (P25, Degussa). Obviously, vacuum annealing-triggered decomposition of ethanol played an important role in the modification of TiO₂. In the presence of ethanol, vacuum annealing was also suitable for the introduction of Vo into P25. Therefore, the current work offers an easy approach for the modification of TiO₂ to enhance its photocatalytic performance by facile vacuum annealing in the presence of ethanol.