Fabrication of MEMS-based Acetone Gas Sensor using CeO2 Nanodots Decorated WO3 Nanowires.

Preparation of reliable, stable and highly responsive gas sensing devices for detection of acetone has been considered to be a key issue for development of accurate disease diagnose systems via exhaled breath. In this paper, novel CeO2 nanodots-decorated WO3 nanowires are successfully synthesized through a sequential hydrothermal and thermolysis process. Such CeO2 nanodots-decorated WO3 nanowires exhibited a remarkable enhancement in acetone sensing performance based on a miniaturized MEMS device, which affords high response (S = 1.30 to 500 ppb, 1.62 to 2.5 ppm), low detection limit (500 ppb), and superior selectivity towards acetone. The improved performance for acetone sensor is likely to be originated from the fast carrier transportation of WO3 nanowires, formation of the WO3-CeO2 heterojunctions, and the existence of large amounts of oxygen vacancies in CeO2. The improved reaction thermodynamics and sensing mechanisms have also been revealed by the specific band alignment and X-ray photoelectron spectroscopy analysis.