Abstract
Novel visible light photocatalytic graphitic carbon nitride/TiO2(g-C3N4/TiO2) composite samples were synthesized by heating mixtures of melamine and commercial TiO2(TO) at different weight ratios. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffused reflectance spectroscopy (UV-vis DRS). Characterization confirms formation of nanocomposites of g-C3N4/TiO2. At the optimized precursor weight ratio (melamine:mTiO2=2.5), the samples exhibited highest adsorption capacity and visible light photocatalytic activity, measured by degradation of methylene blue (MB). Under visible light irradiation, the excited electrons on the surface of g-C3N4transfer easily to the conduction band (CB) of TiO2via the well-built heterojunction. The g-C3N4/TiO2nanocomposites exhibit enhanced visible light catalytic activity due to increased visible light adsorption and effective separation of photogenerated electron-hole pairs. These g-C3N4/TiO2nanocomposites could find broad applicability in environmental protection due to their excellent visible light photocatalytic property and facile, cost-effective preparation process.
Highlights
Visible light photocatalysis has attracted much attention due to its extensive application in the fields of hydrogen generation [1, 2] and environmental protection [3, 4]
The peak intensity at 27.5∘ corresponding to g-C3N4 increases with increasing weight ratio of melamine, which confirms that g-C3N4 has been produced in the as-prepared samples and the yield of it gradually increased
Conclusions g-C3N4/TiO2 nanocomposite samples were simplistically synthesized by thermal treatment of mixtures of industrial TiO2 and melamine at different weight ratios
Summary
Visible light photocatalysis has attracted much attention due to its extensive application in the fields of hydrogen generation [1, 2] and environmental protection [3, 4]. TiO2 has been proved to be a competent photocatalyst for environmental applications; due to the wide band gap of anatase TiO2 (3.2 eV), it cannot be excited under visible light irradiation (λ > 400 nm) [5]. Yan and Yang reported a TiO2-g-C3N4 composite material for photocatalytic H2 evolution under visible light irradiation [2]. Yang et al reported that N-doped TiO2/g-C3N4 composites with enhanced daylight photocatalytic properties were prepared by heating titanium tetrachloride ethanol solutions with C3N4 [10]. Fu et al reported a solid-state approach to synthesizing g-C3N4 coated TiO2 nanocomposites from urea and commercial TiO2 precursors [12]; the preparation conditions and proposed mechanism for enhancing photocatalytic activity of g-C3N4/TiO2 require further research. Photocatalytic efficiency of the as-prepared g-C3N4 coated TiO2 nanocomposites was determined by degradation of methylene blue (MB) dye under visible light irradiation
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