Hydrothermal synthesis and performance of a novel nanocrystalline Pb(2)Sn(2)O(6) photocatalyst

A novel nanocrystalline Pb(2)Sn(2)O(6) photocatalyst was prepared successfully for the first time by a hydrothermal process at 180 degrees C for 12 h. The samples were characterized by an x-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), surface area (BET) and ultraviolet-visible (UV-vis) spectroscopes. The results showed that the pH value played an important role in controlling the phase formation and crystallite sizes of the Pb(2)Sn(2)O(6). A single phase could be obtained at a pH>/=9. A possible reaction mechanism in the hydrothermal process was also proposed. The average particle size for the sample prepared at pH = 13 was only about 9 nm, and the BET surface area was as large as 76.7 m(2) g(-1). The N(2) adsorption-desorption isotherms and pore size distribution curve demonstrate a mesoporous structure with a narrow pore size distribution. As a novel photocatalyst, the prepared Pb(2)Sn(2)O(6) samples exhibit powerful photocatalytic activity for the decomposition of methyl orange under 365 nm UV light irradiation. Furthermore, it was found that the degradation process may be initiated directly by photogenerated holes rather than commonly sensed hydroxyl radicals.