Synthesis of TiO 2 nanoparticles through the Gel Combustion process F. A. Deorsola Æ D. Vallauri Received: 10 December 2007 / Accepted: 6 February 2008 / Published online: 11 March 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Nanosized titania particles have been synthe- sized through the Gel Combustion process. The synthesis was carried out by starting from a common and low-cost titanium precursor and hydrogen peroxide as combustible substance. The process led to a significant gas development and the as-synthesized nanoparticles showed a low degree of crystallinity and mean dimension of 20 nm. Different thermal treatments were performed so as to investigate their effect on the structural properties and on the particle size of the synthesized products. The optimal temperature was set at 300 °C, giving pure anatase TiO 2 nanopowders with a good level of crystallinity, an average particle size of 50 nm and a high value of specific surface area. Introduction Titanium dioxide TiO 2 has received in the last years growing attention thanks to its interesting properties that allow its employment in a wide range of applications, such as pigments [1], medical devices [2] and gas sensing [3]. In particular, the attention has been recently focussed on the semiconducting and photosensitive behaviour, exploited in several applications concerning the environmental field, such as purification of air and water from pollutants [4] and solar cells for low-cost photovoltaic devices [5]. The morphology of the TiO 2 particles significantly affects their catalytic and electrical behaviour, so that a great effort has been made in the development of innovative processes for obtaining nanosized particles. Several new processes and technologies have been developed in recent years for the production of titanium dioxide nanopowders, such as gas condensation [6], sol–gel [7] and hydrothermal synthesis [8]. The Gel Combustion process, belonging to the solution combustion syntheses, seems to be an interesting and powerful method for the synthesis of metal oxide nano- particles. The process, developed at the beginning of the nineties, is performed in the middle between sol–gel and combustion, combining chemical gelation techniques and combustion processes. It is based on the Pechini synthesis [9] and it uses a redox mixture, containing an oxidizer and a fuel compound. The process involves an exothermic decomposition reaction of an aqueous gel and a thermally induced anionic redox reaction. The reaction produces nanostructured powders at rather low temperatures. The powders are slightly bonded into soft and very porous agglomerates. The Gel Combustion process has been extensively employed in the last years for the synthesis of nanoparticles of a number of metal oxides, such as SnO 2 [10, 11], NiO [12], yttria stabilized zirconia [13] and fer- rites [14]. On the other hand, a limited number of studies have been dedicated to the investigation of the Gel Com- bustion synthesis for the preparation of both pure and doped titanium oxide nanopowders. Among the literature works related to similar methods, Sivalingam and co- workers synthesized nano-sized, high surface area TiO 2 by a solution combustion method for the photodegradation of poly(bisphenol-A-carbonate) in solution [15] and for the degradation of various dyes [16]. Yan et al. produced highly dispersed TiO 2 nanometric powders with controlled structure by a complex sol–gel auto-igniting chemical F. A. Deorsola (&)  D. Vallauri Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy e-mail: fabio.deorsola@polito.it 123 J Mater Sci (2008) 43:3274–3278 DOI 10.1007/s10853-008-2530-4