Comparison of the Melon Nanocomposites in Structural Properties and Photocatalytic Activities

Abstract

A simple method was used to prepare SiO2-melon nanocomposites and TiO2-melon nanocomposites. The nanocomposites structure has been extensively characterized and compared by using UV–visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry analysis (TGA), solid state 13C and 1H nuclear magnetic resonance spectroscopy (13C NMR, 1H NMR), differential scanning calorimetry (DSC), elemental analysis (EA) as well as Fourier transform infrared spectroscopy (FT-IR). It has been found by FT-IR, TGA, 13C NMR, and EA results that melon was present in the nanocomposites only when the metal oxide does not undergo phase transformation during the sample preparation. In addition, TGA, DSC, XRD, and TEM data seem to imply that the interaction of melon with TiO2 was more extensive than with SiO2. UV–visible spectroscopy revealed that the absorption edge of the nanocomposites was located in visible light region and was likely attributed to absorption of melon or melon-metal oxide charge transfer. Hence, melon could function as the photocatalytic active site of the nanocomposites in the degradation of methylene blue under visible light. Interestingly, it was found that the photocatalytic activity difference between the two melon nanocomposites is due to (i) the effectiveness of synergism between the melon and the metal oxide and (ii) the amount of interaction between the melon and the metal oxide.