Ultrafast response and recovery ethanol sensor based on SnO2 quantum dots

•SnO2 quantum dots (QDs) have been prepared by a simple precipitation method.•SnO2 nanoparticles with different size have been obtained by annealing the SnO2 QDs.•SnO2 nanoparticles show high sensitivity, fast response (1 s) and recovery (1 s) to ethanol.

SnO2 quantum dots (QDs) with diameter of ~2.5 nm has been successfully synthesized by a simple precipitation method without using any capping agent or organic solvent at room temperature, and SnO2 nanoparticles with different diameter were obtained by annealing the as-synthesized SnO2 QDs at different temperature. The SnO2 nanoparticle with small size of 3.7 nm presents high sensing response and ultrafast response (1 s) and recovery (1 s) to ethanol.