Fast microwave-assisted synthesis of gas-sensing SnO2 quantum dots with high sensitivity

Tin oxide (SnO 2 ) quantum dots (QDs) have been prepared by microwave-assisted method. Firstly, through microwave-assisted method, organic component-wrapped SnO 2 QDs with size of ca. 2–4   nm can be synthesized in only 0.5   min at 160   °C. Then, SnO 2 of very good crystallinity and ca. 5–10   nm can be obtained by annealing the organic component-wrapped SnO 2 QDs in air at 400   °C for 4   h. The annealed SnO 2 QDs exhibit excellent gas sensitivity towards ethanol vapor. Typically, the relative resistance, i.e., ratio of resistance of sample in air to that in tested gases, of sensors towards 300   ppm of ethanol vapor is 215.