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a b s t r a c tA series of TiO 2 hybrids composited with exfoliated g-C 3 N 4 nanosheets (CNs) were successfully synthesized through a facile sol-gel method and fully characterized by X-ray diffraction patterns (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-vis diffuse reflectance spectra (UV-vis DRS). The CNs-TiO 2 hybrids were exposed to visible light irradiation and showed much higher catalytic capability toward degrading dye rhodamine B (RhB) comparing with bare TiO 2 and N-TiO 2 . The sample CNs-TiO 2 -0.05 exhibited the largest apparent reaction rate constant among all CNs-TiO 2 hybrids, which was 2.4 times and 7.0 times as high as bare TiO 2 and N-TiO 2 , respectively. The enhanced catalytic efficiency could be mainly attributed to the well-matched band gap structure with heterojunction interface, suitable specific surface area, and favorable optical property. In addition, active species trapping experiments were conducted, revealing that photoinduced holes (h + ) had a severe influence on catalytic outcome, through which a possible catalytic mechanism was finally realized and proposed.

Exfoliated g-C 3 N 4 nanosheets (CNs) were composited with bismuth oxychloride (BiOCl) to fabricate a series of hybrids via a facile chemical deposition-precipitation method in this investigation. The as-synthesized BiOCl-CNs hybrids were then fully characterized by a collection of analytical techniques. It was obviously observed that CNs were in intimate contact with hierarchical BiOCl flowerlike units to form heterojunction structures, which facilitates transfer and efficient separation of photoinduced electronhole pairs, thus greatly increasing catalytic activity upon visible light irradiation. Together with other merits such as enlarged specific surface area, favorable optical properties, and suitable energy-band structures, these robust BiOCl-CNs hybrids showed significantly enhanced photocatalytic performance towards Rhodamine B (RhB) dye removal. Under identical conditions, the apparent photocatalytic reaction rate of the best hybrid BiOCl-CNs-3% was about 2.1 and 26.6 times as high as those of BiOCl and CNs alone, respectively. A possible photocatalytic mechanism was also proposed by means of active species trapping measurements, revealing that superoxide radicals (cO 2 À ) played a crucial role during the catalytic process.

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