Probing the facet-dependent intermediate in the visible-light degradation of RhB by carbon-coated anatase TiO2 nanoparticles

The Facet-dependent photocatalytic process related to the degradation of organic pollutants by semiconductor catalysts is of great significance for understanding the photocatalytic mechanism of nanomaterials and improving their catalytic performance. Herein, the titanium dioxide catalysts with {001} or {101} dominant exposed facets coated with carbon (TiO2(001)/C and TiO2(101)/C) were synthesized by a hydrothermal method, and the photo-degradation research of rhodamine B (RhB) was analyzed by using UV-visible absorption spectroscopy, fluorescence spectroscopy and time-resolved fluorescence spectroscopy. The results demonstrated that the degradation of RhB was the competition for both N-deethylation and the destruction of aromatic ring reactions. The N-deethylation of RhB molecules dominated the reaction in the TiO2(001)/C system during the initial irradiation period. Whereas, both N-deethylation and cleavage of the aromatic ring occurred simultaneously in TiO2(101)/C/RhB system. The results of the fluorescence spectra and fluorescence lifetime analysis also suggested that the degradation rate of the intermediate product (Rh-110) is faster for TiO2(001)/C than TiO2(101)/C. We proposed a possible explanation that the carbonaceous species on the surface of TiO2 can absorb visible light to assist the degradation of RhB. The difference in surface properties and energy band structures lead to the different degradation processes and facet dependent features. Our findings presented the intermediate evidences for revealing the relation between the photocatalytic activity and exposed facets of TiO2 nanoparticles. (C) 2020 Elsevier B.V. All rights reserved.