Hydrothermal routes to prepare nanocrystalline mesoporous SnO₂ having high thermal stability

We report simple hydrothermal routes to prepare thermally stable SnO ₂ particles having high specific surface areas and mesoporosity. The preparation method includes a new combination of synthetic processes: hydrolysis of tin(IV) chloride at 95°C in the absence of alkaline solutions (aqueous NH₃ or NaOH), formation of nanocrystalline SnO₂, and subsequent hydrothermal treatments at temperatures between 100 and 200°C. After annealing treatments of the hydrothermally treated SnO ₂ particles at 400 or 500°C, their crystallite sizes remained smaller than 7.7 nm and their specific surface areas were still higher than 110 m²/g, indicative of the high thermal stability against particle growth and sintering. Furthermore, mesoporosity evolved with a relatively narrow pore size distribution typically in the range of 3.0-4.3 nm. The effects of the hydrothermal treatment were explained by uniformization of the particle size that was beneficial to the suppression of particle growth.