Preparation and Structural Properties of Tin Oxide−Montmorillonite Nanocomposites

Abstract

Tin oxide intercalated montmorillonite nanocomposites were prepared by an in situ preadsorption method in aqueous solution in the absence of surfactants and organic solvents. The tin oxide particle size was controlled by adjusting the relative supersaturation ratio, S (S ) (Q -L)/L), where Q is the amount of the dissolved material, the Sn(OH)4 precipitate, and L is its solubility). Increasing the relative supersaturation results in a progressive increase of the size of the SnO2 nanoparticles up to a maximum, after which a further increase of S results in a decrease of the size of the nanoparticles, since their growth is inhibited. Calcination of the 2-3 nm diameter SnO2/Sn(OH)4 nanoparticles at 400 °C for 3 h resulted in the formation of an oxide lattice structure from a tin oxide/hydroxide structure. XRD measurements indicated the sizes of tin oxide nanocrystals to be in the 1-2 nm diameter range between the layers of montmorillonite. The specific surface area of montmorillonite significantly changed from 30 to 112.5 m 2 /g upon SnO2 intercalation, as evidenced by BET. The thermoanalytical investigations revealed the optimal calcination temperature of the nanocomposites (400 °C) and proved the presence of the SnO 2 nanoparticles by the heat effect of their crystallization process. The Mo ¨ssbauer studies of the samples indicated the particle size dependence on the effective vibrating mass (Meff) and the Debye temperature (ΘM) of the tin oxide nanocrystals. It was confirmed by all of the measurement methods that smaller particle size can be attained by increasing the relative supersaturation ratio of the Sn(OH) 4 precipitate.

Electrodeposition of nanocrystalline SnO2 coatings with two-layer microstructure

“…The high porosity and large surface area allows active species in solution or in air to rapidly react with the coating. The BET surface area of the electrodeposited tin oxide can be comparable to, or even better than, those of tin oxide powders synthesized via other processes (20-86 m 2 /g) [30][31][32]. In the condition of particles aggregation, the high surface area of electrodeposited SnO 2 coating can be attributed to the extremely fine particle size.…”

Preparation, characterization and photoelectrocatalytic properties of nanocrystalline Fe2O3/TiO2, ZnO/TiO2, and Fe2O3/ZnO/TiO2 composite film electrodes towards pentachlorophenol degradation

“…11 ZnFe 2 O 4 has been successfully tested as a heterogeneous catalyst and its first use in photocatalysis has been reported by Valenzuela. 12 MOx-TiO 2 composite thin film electrodes were obtained by a sol-gel process with two aims [13][14][15][16][17] : (A) extending the light adsorption spectrum and improving the using efficiency of the light; (B) suppressing the recombination of photogenerated electron/hole pairs. Up to now, to our knowledge, preparation, characterization and use of novel composite Fe 2 O 3 / ZnO/TiO 2 and ZnO/TiO 2 film electrode have not been reported.…”

Synthesis of yttria nanoparticles using NIPAM/AAc copolymer

“…It is obvious that particle size of precipitate is affected by some empirical variables such as solubility, temperature, concentration of reactants and reaction time. Without going into detail, it has been shown (von Weimarn) that the particle size of precipitates is inversely proportional to the relative supersaturation of the solution during precipitation (Barlow et al , 2004; Nemeth et al , 2003; Schierholtz, 1958). The higher the supersaturations the lower the mean particle size.…”