The dependence of morphology, structure, and photocatalytic activity of SnO₂/rGO nanocomposites on hydrothermal temperature

In this work, we determined the morphological, structural, and photocatalytic properties of SnO₂/rGO nanocomposites dependent on hydrothermal synthesis temperature. SnO₂/rGO nanocomposites were synthesized with a hydrothermal method from SnCl₄.5H₂O, NaOH, and graphene oxide (GO) precursors at temperatures ranging from 100 to 200 °C. X-ray diffraction (XRD) analysis showed that the average particle size of SnO₂ nanocrystals increased with hydrothermal temperature, although the tetragonal rutile crystalline structure of SnO₂ did not change as the hydrothermal temperature increased. SnO₂ nanoparticles and reduced graphene oxide (rGO) sheets were observed in all SnO₂/rGO samples obtained with different hydrothermal temperatures. Raman spectra indicated that GO was successfully reduced to rGO, and that SnO₂ nanocrystals formed during the hydrothermal process. At an excitation wavelength of 270 nm, the photoluminescence emission band of SnO₂ nanocrystals increased in intensity with increasing hydrothermal temperature, while the emission intensity of the SnO₂ defects decreased. The photocatalytic properties of the nanocomposites were significantly improved when the hydrothermal temperature was raised from 100 to 180 °C. (paper)