Influence of Hydrothermal Temperature on Structures and Photovoltaic Properties of SnO2 Nanoparticles

Two SnO2 nanoparticles were synthesized by hydrothermal method at 170 °C and 180 °C, respectively. Transmission electron microscope observations reveal that the diameters of both the nanoparticles are around 6 nm. At the same time, surface photovoltage spectroscopy measurements show that the nanoparticle synthesized at 180 °C has more surface electronic states at 0.3 eV below the conduction band than the one synthesized at 170 °C. This means that the temperatures chosen in hydrothermal synthesis have significant influence on the surface electronic characteristics of resultant SnO2 nanoparticles but the effect on their sizes is not obvious. However, after being calcined at 500 °C for 2 h, the diameter of the nanoparticle synthesized at 180 °C increased to 23 nm and that of the nanoparticle synthesized at 170 °C increased to 32 nm as calculated from X-ray diffraction pattern.