Structural evolution and optical properties of C-coated TiO2 nanoparticles prepared by laser pyrolysis

• Published in: Applied surface science 2013-08, Vol.278, p.295-300
• Main Authors: Scarisoreanu, M., Alexandrescu, R., Morjan, I., Birjega, R., Luculescu, C., Popovici, E., Dutu, E., Vasile, E., Danciu, V., Herlin-Boime, N.
• Format: Article
• Language: English
• Subjects: Band gap energy; C-doped TiO2; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Laser pyrolysis; Nanoparticles; Physics; UV–vis transmission
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.01.052

► Carbon-doped TiO2 nanoparticles (using acetylene as precursor) were successful synthesized by the single step laser pyrolysis. ► Nanoparticles with major anatase TiO2 phase and different C concentrations (C/Ti (in at.%)=0.6–0.8) were prepared. ► Laser synthesized samples have a lower bandgap energy (Eg=2.59eV) than the TiO2 Degussa commercial sample. Carbon- coated TiO2 nanoparticles were prepared by the IR laser pyrolysis technique. A sensitized mixture of TiCl4 and alternatively C2H4 and C2H4/C2H2 mixtures were used as titanium and carbon precursors, respectively. Optical, morphological and structural properties of the samples have been characterized by X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy, selected area electron diffraction analysis and UV–vis diffuse reflectance spectroscopy. The phase composition of the nanoparticle system contains a mixture of anatase and rutile, with a preponderance of the anatase phase (90%) and with mean particle size of about 20nm. The effect of increased carbon-dopant concentration on the essential structural properties of C-TiO2 nanopowders has been determined to be a decrease of the TiO2 anatase phase and of the particle mean diameter value (to about 18nm). For the C-doped TiO2 nanoparticles, the UV–vis diffuse reflectance spectra showed an absorption shift to longer wavelengths, thus demonstrating an enhancement of the absorption in the visible spectrum.