SnO2 monolayer porous hollow spheres as a gas sensor.

The authors report on gas sensing properties of SnO2 hollow spheres with diverse microstructures, which are synthesized through controlled precipitation of Sn(OH)4 layers on carbon sphere templates, followed by heat treatment at different temperatures. Hollow spheres derived at 973 K consist of monolayer SnO2 grains, which lead to a huge activated surface area. The sensitivity of sensors based on SnO2 monolayer hollow spheres is up to 51 at 100 ppm ethanol, which is much higher than that of two other samples. We attribute this enhancement mostly to the enhanced depletion effect arising from the increased exposed surface. Our results suggest a direction for improving the performance of gas sensors by using monolayer porous hollow spheres.