ผลของการโหลดกราฟีนต่อลักษณะเฉพาะการตอบสนองแก๊สของอนุภาคนาโนทังสเตนไตรออกไซด์

Abstract

The gas sensors based on flame-synthesized WO3 nanoparticles loaded with 0.2-5 wt% electrochemically exfoliated graphene have been evaluated under exposure of NO2. The characterizations by XRD, Raman spectrometry, XPS, BET, SEM, EDS, and TEM have been signified the accurate phase, crystallinity, and high specific surface area of spheroidal WO3 nanoparticles and its characteristics of porous composites films with different graphene loading levels. The pristine WO3 nanoparticles have been homogeneously mixed with different graphene loading levels by using the binder, subsequently spin-coated on Au/Al2O3 substrate to form sensing layers and then annealed at 450°C for 2 h prior to sensing test. The fabricated sensors have been evaluated to 50-5000 ppb NO2 with different operating temperatures ranging from 100-350 °C in dry air. It can be noticed that the as-prepared WO3 nanoparticles loaded with optimal 2 wt% graphene evidently performed the highest sensor response to 5,000 ppb NO2 of ~ 5,061 at temperature of 150 °C comparing to lower and higher graphene loading levels. Furthermore, the sensor based on 2 wt% graphene/WO3 composites displayed high selectivity to low detection of 5,000 ppb-NO2 against to those of the other environmental gases including toxic gases, flammable gases, volatile organic acids, and volatile organic compounds at 150 °C. The mechanistic roles of different graphene loading levels on NO2 gas-sensing performances were interpreted in the basis of M-S heterointerfaces, resulting in resistance changes at the reactive interfaces of the composites materials. Therefore, the incorporation of graphene loaded WO3 nanoparticle-based sensors is an attractive choices for selective detection of NO2 at ppb levels.