Enhancement of methylmercaptan sensing response of WO3 semiconductor gas sensors by gas reactivity and gas diffusivity

Abstract

WO3-based semiconductor-type gas sensors were fabricated, and their sensing properties to methylmercaptan (CH3SH) were examined in this study. The Ru loading on WO3 was an effective way of an increase in the CH3SH response. In addition, the CH3SH response increased with a decrease in the operating temperature as well as with an increase in the thickness of the Ru-loaded WO3 sensing layer. The increase in the porosity of the Ru-loaded WO3 sensors, which were fabricated by utilizing polymethylmethacrylate microspheres as a template, was also effective in improving the CH3SH response, especially at a low temperature of 150°C. In addition, the lamination of the Ru-loaded WO3 sensor with an α-Al2O3 film improved the CH3SH response at 200°C. Moreover, the Ru loading on the WO3 powder increased the catalytic activities of CH3SH oxidation, and CH3SH was partially oxidized to CH3SSCH3 at temperatures less than 330°C. It was suggested that the increase in the positively charged adsorption of the partially oxidized products onto the bottom part of the sensing layer is effective for enhancing the CH3SH response, especially at lower operating temperatures.

CH3SH and H2S Sensing Properties of V2O5/WO3/TiO2 Gas Sensor

“…The synthesized VWT particles had a diameter of several tens of nanometers, and no V-W-Ti-O composite oxide was It was found that at 300 • C, the 3 VWT gas sensor had good gas selectivity against H 2 gas and a high CH 3 SH response of 500 ppb (S = 1.74). This CH 3 SH response value is smaller than that of the WO 3 gas sensor in earlier reports [10,11]. In this study, the H 2 S, CH 3 SH, and H 2 gas response characteristics in dry atmosphere were measured only once.…”

“…Semiconductor-based gas sensors are effective for respiratory gas analysis from the standpoints of cost, compactness, and power consumption [6][7][8][9][10][11]. Su et al reported that for NO 2 sensing, a wearable, alveolus-inspired active membrane sensor based on the WO 3 system showed excellent selectivity and thermal and humidity stability [6].…”

Highly Sensitive and Selective NiO/WO3 Composite Nanoparticles in Detecting H2S Biomarker of Halitosis

“…Meanwhile, methyl mercaptan (CH 3 SH) is an important biomarker of halitosis as well. 35,36 Hence, we investigated the sensing response to methyl mercaptan and propanediol as interfering gases. In Figure S6 (Supporting Information), the response of 2.1 wt % NiO/WO 3 NPs to 100 ppm methyl mercaptan and 600 ppm propanediol is R a /R g = 1813, which is much lower than the response to H 2 S. Further, the long-term stability (see Figure 3f) of the 2.1 wt % NiO/WO 3 NP sensor to 10 ppm H 2 S was testified at 100 °C for 30 days, and the sensor showed excellent stability.…”

Application of Metal-Organic Framework-Based Composites for Gas Sensing and Effects of Synthesis Strategies on Gas-Sensitive Performance

“…However, this material cannot address other limitations and cannot detect responses at the ppb or sub-ppm level [81]. In addition, experimental studies have found that methods including ion doping [82], modification using noble metals [83], hybridization with catalysts, and functionalization with sensing probes [84,85] or the use of heterostructures [86] can also improve gas sensing performance. Remaining challenges include the ability to further enhance selectivity for molecules with a similar sensing activity and dealing with interference with water vapor.…”