Construction of carbon dots-deposited TiO2 Photocatalysts with visible-light-induced photocatalytic activity for the elimination of pollutants

Abstract

Element decomposition is a promising modification technique for enhancing the photocatalytic activity of TiO2. Firstly, (i) It may accelerate photogenerated electron–hole separation as electron traps, (ii) broaden the sunlight absorption region into the visible range and promote surface electron excitation by plasmon resonances excited under visible light and (iii) modify the surface performance of semiconductors. Herein, we describe the introduction of carbon dots (CDs) as solid-state electron mediator on TiO2 sheets (TNs) via a highly effective hydrothermal process. The as-prepared CDs/TNs nanocomposites was measured by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, UV–visible diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy analysis. The results proved that CDs were firmly scattered in the TNs interface. Furthermore, the resultant CDs/TNs nanocomposites exhibited remarkable photocatalytic activity for the degradation of different model pollutants under visible light, which is considerably superior to that of bare TNs. The enhanced photocatalytic activity highlights that CDs can promote the separation and migration efficiency of photoexcited electron–hole pairs. The striking stability of CDs/TNs was investigated by performing five successive cycles of degradation of Congo red. Moreover, the degradation intermediates of three pollutants were monitored by liquid chromatography-tandem mass spectrometry, and potential removal pathways are proposed. We firmly believe that this work may inspire new insights and approaches for the design of highly efficient photocatalysts.