High-yield synthesis of SnO2 nanobelts by water-assisted chemical vapor deposition for sensor applications

Well-crystallized one-dimensional (1D) SnO2 nanobelts were in situ prepared using a simple water-assisted chemical vapor deposition (CVD) method. The small Sn particles with Au-modifications were used as source materials instead of big size Sn grains to ensure the high yield of SnO2 belts. The Au layer was modified on the small Sn particles by treating Sn powders in HAuCl4 solution combined with the UV irradiation. The as-prepared SnO2 nanobelts were characterized by SEM, HRTEM, XRD, EDS and XPS. These results indicate that the growth temperature plays an important role in controlling the length-to-width ratio of nanobelts. The length-to-width ratio decreases with the growth temperature from 850 °C to 1000 °C. The nanobelts prepared at 850 °C shows a single-crystalline tetragonal rutile phase with a high length-to-width ratio (approximately tens of microns in length and 40–70 nm in width). However, below 850 °C, nanobelts cannot be formed. The as-prepared nanobelts exhibited excellent sensing properties compared with SnO2 nanoparticles and high sensing selectivity towards NO2. The high sensing selectivity to NO2 is attributed to the oxygen vacancies presenting in the as-prepared nanobelts.