Iron and carbon codoped WO3 with hierarchical walnut-like microstructure for highly sensitive and selective acetone sensor

Current metal-oxide-based sensing materials are confronted with several challenges, especially in sensitivity, selectivity and stability, for their application in the breath acetone analysis. Herein, hierarchical walnut-like Fe-C-codoped WO3 microspheres were synthesized and characterized by X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The amount of Fe doping was optimized based on detecting the acetone responses dependent on the operating temperature. The sensor based on the optimal Fe-C-codoped WO3 (FW3) exhibited high response to acetone and very low responses to NH3, CO, toluene, methanol, ethanol and NO. The results indicate that the optimized material possesses high sensitivity and good selectivity toward acetone vapor. Besides, the FW3 sensor presented superior anti-interferential ability to various mixed-gas systems. More importantly, the responses of the sensor exhibited no obvious fluctuation over 12 weeks, implying good long-term stability of the synthesized material. We suggest that the phase, morphology and the increased number of oxygen vacancies induced by Fe doping are the underlying reason for the improved gas sensing performance of the Fe-C-codoped WO3 microspheres. (C) 2017 Elsevier B.V. All rights reserved.