Visible-light photocatalytic SiO sub(2)/TiO sub(2-x)C sub(x)/C nanoporous composites using TiCl sub(4) as the precursor for TiO sub(2) and polyhydroxyl tannin as the carbon source

• Published in: Catalysis science & technology 2012-02, Vol.2 (2), p.390-399
• Main Authors: Zhang, Juzheng, Grabstanowicz, Lauren R, Gao, Shanmin, Hosmane, Narayan S, Huang, Baibiao, Dai, Ying, Liu, Di-jia, Xu, Tao
• Format: Article
• Language: English
• Subjects: Nanocomposites; Nanomaterials; Nanostructure; Photocatalysis; Precursors; Silicon dioxide; Titanium dioxide; X-rays
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c1cy00403d

We report an architecturally controlled synthesis of SiO sub(2)/TiO sub(2-x)C sub(x)/C nanoporous composites that exhibit high absorption capability and efficient visible-light photocatalytic activity. The nanoporous composites are composed of silica particles as the cores and TiCl sub(4) as the precursor for the TiO sub(2) shell. Tannin is used as the binding agent between the core and the precursor shell, the carbon source, and the porosity promoter. The structure, crystallinity, morphology, and other physical-chemical properties of the samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microcopy (HRTEM), X-ray photoelectron spectroscopy (XPS), N sub(2) adsorption-desorption isotherm measurements, UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL). The chemical contents of the SiO sub(2)/TiO sub(2-x)C sub(x)/C nanoporous composites were also analyzed by energy dispersive X-ray spectra (EDX). The formation mechanism of the nanoporous composites was extensively discussed. Methylene blue (MB) solutions were used as model wastewater to evaluate the adsorption and photocatalytic activity of the samples under natural sunlight and visible light. Fourier transform-infrared spectroscopy (FT-IR) and mass spectrometry (MS) were used to investigate the photodegradated species on the photocatalysts and in solution, respectively. The SiO sub(2)/TiO sub(2-x)C sub(x)/C nanoporous composite samples exhibit remarkably enhanced visible-light photoactivity than Degussa P25 and pure TiO sub(2), and can be readily collected for reuse by gravitational sedimentation.