Size-controllable one-dimensinal SnO2 nanocrystals: synthesis, growth mechanism, and gas sensing property

Single crystalline one-dimensional (1-D) SnO2 nanocrystals with controllable sizes, including the diameter and the aspect ratio, were synthesized by modulating the precursor concentration, reaction time and temperature via a solution method. By regulating the growth in a kinetic regime, a higher temperature range (220 - 240 degrees C) was beneficial to the growth of SnO2 nanowires, while reactions below 220 degrees C only resulted in nanorods or even nanoparticles. The aggregates of SnO2 nanocrystals in the forms of hollow spheres and dendrites were observed as the intermediates for the nanowires. Based on the TEM and SEM observations, the growth mechanism is discussed from the viewpoints of the nature of the reverse micelles and the crystal habit of rutile SnO2. CO gas sensing measurements were also carried out for SnO2 nanocrystals with different assembly styles. The results indicate that the sensitivity had close correlation to the specific surface area of the nanocrystals.