Enhancement mechanisms of ethanol-sensing properties based on Cr2O3 nanoparticle-anchored SnO2 nanowires

Abstract

Cr2O3 nanoparticle-anchored SnO2 nanowires are synthesized to fabricate highly sensitive and selective ethanol gas sensor. SnO2 nanowires are synthesized by vapor-liquid-solid method as a gas detection material, and Cr2O3 nanoparticles are anchored to SnO2 nanowires to improve sensing properties. Anchoring Cr2O3 nanoparticles are synthesized to deep the SnO2 nanowire sample to chromium oxide colloid gel, and anneal this sample at 500°C, in a vacuum atmosphere. This hybrid structured sensor presents 4 times improved ethanol sensing response compared with as-synthesized SnO2 nanowires when exposed to 100ppm ethanol gas in 300°C. Furthermore, sensing selectivity of ethanol versus other volatile organic compound (VOC) gas is also drastically improved. Generally, nanostructured SnO2 is known as very sensitive material to chemical gas, but it is hard to apply to commercial gas sensor since its extremely low selectivity. However, using this hybrid structured sensor, highly sensitive and selective ethanol sensor can be fabricated. This improvement of ethanol sensing properties can be explained that variation of energy bandgap of homojunction between n-SnO2 and n-SnO2 and heterojunction between n-SnO2 and p-Cr2O3 of nanowires. Furthermore, catalytic properties of this hybrid structure nanowire make selectivity of sensor improved.