Surface chemistry of surfactant AOT-stabilized SnO2 nanoparticles and effect of temperature

SnO2·xH2O nanoparticles were prepared at room temperature by the microemulsion route. Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used as a surfactant to stabilize the nanoparticles. These nanoparticles show green luminescence at 510 nm, which has been assigned to oxygen vacancies. Infrared spectra of samples heated in the temperature range 500–900 °C show bond formation between SnO2 nanoparticles and SO42-, which arises from oxidation of SO3- present in AOT. This was further supported by X-ray diffraction. Shape transformations of the particles from triangular to spherical and then to rectangular was observed as the heat-treatment temperature was increased, and this is related to the surface energy of particles. An enhancement in emission intensity of Eu3+ was observed when Eu3+ ions were doped into the SnO2 nanoparticles due to significant energy transfer from SnO2 (or Eu–O) to Eu3+ through surface-mediated energy transfer as compared to direct excitation of Eu3+ at 397 nm. Interestingly, these nanoparticles are dispersible in water, and can be incorporated into polymer-based materials such as polyvinyl alcohol to give homogeneous films, giving rise to blue and red emissions.

Interaction of sulfonate group of the surfactant AOT with SnO2 nanoparticles before and after heat treatment.Figure optionsDownload high-quality image (64 K)Download as PowerPoint slideResearch highlights
► Synthesis of SnO2 nanoparticles by AOT/hexane/water microemulsion route.
► Interaction of surfactant AOT with SnO2 nanoparticles.
► New IR peak at 1448 cm−1 due to SO42- residue over SnO2.
► SnO2 nanoparticles show green luminescence which is due to oxygen vacancies.