Enhanced Photo-Assisted Acetone Gas Sensor and Efficient Photocatalytic Degradation Using Fe-Doped Hexagonal and Monoclinic WO3 Phase−Junction

Abstract

The development of WO3-based gas sensors for analysis of acetone in exhaled breath is significant for noninvasive diagnosis of diabetes. A series of Fe-doped hexagonal and monoclinic WO3 phase−junction (Fe−h/m−WO3) sensors were synthesized by the hydrothermal calcination method, and the influences of operating temperature and light irradiation on the response were studied. Under light emitting diode (LED) illumination, Fe−h/m−WO3 exhibited higher responses to acetone than those of the undoped WO3-based sensors at an operating temperature of 260 °C with 90% relative humidity, and good linearity between response and acetone concentration (0.5 to 2.5 ppm) was achieved under the 90% relative humidity condition. Meanwhile, the optimal Fe−h/m−WO3 sensor exhibited high selectivity and stability for a duration of three months. The excellent sensing performance of Fe−h/m−WO3 was attributed to the formation of phase−junction and Fe doping, and these were beneficial for the separation of photon−generated carriers and oxygen adsorption on the WO3 surface, promoting the generation of superoxide radicals, which was demonstrated by electron paramagnetic resonance and photocurrent tests. Additionally, the Fe−doped WO3 phase−junction sample also showed good photocatalytic performance for rhodamine B degradation. This study may provide some insights into rational design of new types of gas sensors and offer an alternative for noninvasive diagnosis of diabetes.

High-Performance Cataluminescence Sensor Based on Nanosized V2O5 for 2-Butanone Detection

“…Gas sensors represent a versatile technology for harmful gas monitoring because of their advantages of low-cost, small size and easy operation [ 7 , 8 , 9 , 10 ]. Nowadays, various gas sensors based on different principles, such as electrochemistry [ 11 , 12 , 13 , 14 ], surface acoustic wave [ 15 , 16 ], quartz crystal microbalance [ 17 , 18 ], and cataluminescence (CTL) [ 19 , 20 , 21 ], have been designed for the detection of different analytes.…”

Synthesis Design of Electronegativity Dependent WO3 and WO3∙0.33H2O Materials for a Better Understanding of TiO2/WO3 Composites’ Photocatalytic Activity

“…The band gap values of the WO 3 -NWH-NaX and WO 3 -NWH-KX series (hexagonal crystal phase) were between 2.69 and 2.95 eV, sequentially 2.54 and 2.66 eV, whereas the literature provides values between 2.50 and 2.76 eV for the hexagonal crystal phase. Concerning the WO 3 -AMT-HX series, where monoclinic, hexagonal, and their mixed crystal phases were identified, the band gap values were between 2.25 and 2.94 eV (2.25 eV for 100% monoclinic crystal phase and 2.94 eV for 100% hexagonal crystal phase), whereas, in the literature, monoclinic WO 3 had shown band gap values between 2.64 and 2.85 eV; subsequently, the monoclinic and hexagonal mixture provided a 2.48 eV band gap [50][51][52]. Thus, overall, the band gap values of our samples only slightly overlap with the band gaps values found in the literature.…”

Acetone Vapor-Sensing Properties of Chitosan-Polyethylene Glycol Using Surface Plasmon Resonance Technique

“…In the second step, when the chitosan-PEG sensing layer was exposed to acetone vapor, it reacted with the ionic oxygen species, which consequently led to increase in conductivity due to the release of the captured electron back to the conduction band, which in turn altered the refractive index value. This process is described in a simplified form by Equation ( 6) [54,55]. Conductivity describes how fast an electric charge can pass through a material or medium.…”