Carbon Containing TiO2 Nanoparticles using Flame Synthesis for Photocatalytic Applications

N.K. Memon, D.H. Anjum, S.H. Chung
King Abdullah University of Science and Technology, SA

Keywords: flame synthesis, TiO2, carbon-coating, optical properties

Summary:

The growth of TiO2 nanoparticles with carbon is performed using a flame synthesis process, where the nanoparticle is coated in a thin-layer of graphitic carbon. Such particles have shown to have excellent photocatalytic properties and can be used to enhance water- splitting. Other possible applications include as an electrode for Li-ion batteries, polymer fillers, and pigments. The process for the synthesis of carbon-coated nanoparticles involves using multiple-diffusion flames. Ethylene (C2H4) is used as the precursor carrier gas, which, in a one-step process, enables the growth of carbon-coated nanostructures. The nanoparticles are characterized using x-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis and high-resolution transmission electron microscopy (HRTEM). The TiO2 particle size ranged from 30 to 50 nm with a uniform carbon coating of 3 to 5 nm, as observed by HRTEM. Additionally, the MEDB enabled the production of both crystalline and amorphous nanoparticles, where interestingly the carbon-coating only occurs for crystalline nanoparticles. Optical properties of the carbon-coated TiO2 nanoparticles are determined by performing valence electron energy loss spectrometry (VEELS) analysis using TEM. The results show that crystalline carbon-coated TiO2 have a higher absorption in the optical range due to lower band-gap energy when compared to non-coated TiO2 nanoparticles.