Taziwa R., Meyer E.L., Sideras-Haddad E., Erasmus R.M., Manikandan E., Mwakikunga B.W.
Institute of Technology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa; Centerof Excellencein Strong Mterials, School of Physics, University of Witwatersrand, Braamfontein 2000, Johannesburg, South Africa; Nano Research Centre, PNTC, B. S. Abdur Rahman University, Chennai 600048, India; CSIR National Centre for Nano-Structured Materials, P. O. Box 395, Pretoria 001, South Africa; Department of Physics, University of Malawi-The Polytechnic, Private Bag 303, Chichiri, Blantyre 3, Malawi, South Africa
Taziwa, R., Institute of Technology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa; Meyer, E.L., Institute of Technology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa; Sideras-Haddad, E., Centerof Excellencein Strong Mterials, School of Physics, University of Witwatersrand, Braamfontein 2000, Johannesburg, South Africa; Erasmus, R.M., Centerof Excellencein Strong Mterials, School of Physics, University of Witwatersrand, Braamfontein 2000, Johannesburg, South Africa; Manikandan, E., Nano Research Centre, PNTC, B. S. Abdur Rahman University, Chennai 600048, India; Mwakikunga, B.W., CSIR National Centre for Nano-Structured Materials, P. O. Box 395, Pretoria 001, South Africa, Department of Physics, University of Malawi-The Polytechnic, Private Bag 303, Chichiri, Blantyre 3, Malawi, South Africa
Carbon-modified titanium dioxide nanoparticles (C:TiONPs) have been synthesized by ultrasonic nebulizer spray pyrolysis (USP) and pneumatic spray pyrolysis (PSP) techniques. HRTEM on the NPs shows difference in lattice spacing in the NP structures prepared by the two methods2.02 Å for the USP NPs and an average of 3.74 Å for the PSP NPs. The most probable particle sizes are 3.11 nm and 5.5 nm, respectively. Raman spectroscopy supported by FTIR confirms the TiOpolymorph to be anatase with the intense phonon frequency at 153 cm -1 blue-shifted from 141 cm -1 ascribed to both carbon doping and particle size. A modified phonon confinement model for nanoparticles has been used to extract phonon dispersion and other parameters for anatase for the first time. Electronic measurements show negative conductance at some critical bias voltage, which is characteristic of n-type conductivity in the carbon-doped TiONPs as confirmed by the calculated areas under the I-V curves, a property suited for solar cell applications. Practical solar cells built from carbon-doped TiOelectrodes show up to 1.5 times improvement in efficiency compared to pure TiOelectrodes of similar construction. © 2012 R. Taziwa et al.