Conductive F-doped Tin Dioxide Sol−Gel Materials from Fluorinated β-Diketonate Tin(IV) Complexes. Characterization and Thermolytic Behavior

Abstract

Hydrolysis and condensation of (CH3COCHCOCH3)2SnF(Otert-Am) and (CF3COCHCOCH3)2Sn(Otert-Am)2 gave soluble stannic oxo-oligomers or -polymers including fluorine and β-diketonate groups. Under thermal treatment in air at 550 °C, they yielded nanocrystalline fluorine-doped tin dioxide powders. The amount of remaining ligands in the xerosols depends on the hydrolysis ratio and on the nature of the solvent used, dimethylformamide (DMF) favoring ligand removal. The thermolytic reactions have been investigated by thermogravimetry coupled to mass spectrometry: (1) the β-diketonate ligands pyrolyze in two stages, at 200 and 320 °C, involving two different processes; (2) elimination of polar solvents of high boiling point, such as DMF, occurs up to 300 °C; (3) fluorine is lost as fluorhydric acid from 230 °C. The best strategy to prepare F-doped SnO2 materials by the sol−gel route is thus to start from precursors including Sn−F bonds and to use a polar aprotic solvent of low boiling point such as acetonitrile. It led to nanocrystalline, highly conductive F-doped tin dioxide materials with resistivities 1 order of magnitude lower than that reported for Sb-doped tin dioxide powders.

Development of Nafion/Tin Oxide Composite MEA for DMFC Applications

“…The SnO 2 ·nH 2 O sample displayed a broad absorption band in the region 3600-2500 cm -1 which can be ascribed to H-bonded hydroxyl groups coupled with physisorbed water molecules. The band centered at 1600 cm -1 corresponds to -OH bending mode of water molecules [35,36]. The FT-IR spectra of the sulfated samples shows some differences both in the frequency region of O-H stretching and, especially, in the frequency range of the SO 4 2-stretching vibration.…”

Influence of fluorine doping on the microstructure, optical and electrical properties of SnO2 nanoparticles

“…However, there are few works, which have been reported on synthesis of FTO nanopowder using this method, except from Gamard et al [23] who used it on fluorine doped SnO 2 nanocrystals preparation, starting from organic precursors including Sn-F bonds, and followed by thermal treatment in air at 550 °C to obtain nanocrystalline FTO.…”

Effect of Sintering Temperatures on the Synthesis of SnO2 Nanospheres

“…Tin oxide (SnO 2 ), a ntype semiconductor with a wide band gap (3.6 eV, at 300 K), is well known for its potential applications in gas sensors, dye sensitized solar cells, and transparent conducting electrodes and as a catalyst support [3,4]. Therefore, many processes have been proposed to synthesize SnO 2 nanostructures; some involve dry processes such as sputtering from tin oxide target [5] or from metallic target followed by oxidation [6] and chemical vapour deposition (CVD) [7], while others are based on wet processes, including spray pyrolysis [8] and sol-gel-related methods which have been used to prepare tin oxide coating, particles, and precipitates [9][10][11][12][13][14][15].…”