The Monitoring of H2S and SO2 Noxious Gases from Industrial Environment with Sensors Based on Flame-Spray-Made SNO2 Nanoparticles

The noxious gas sensors were developed successfully using flame-spray-made SnO2 nanoparticles as the sensing materials. The functionalized nanoparticle properties were further analyzed by XRD, BET and TEM analyses. The SnO2 nanoparticles (SSABET: 141.6 m2/g) were investigated revealing non-agglomerated spheroidal, hexagonal, rectangle (3 - 10 nm), and rod-like (3 - 5 nm in width and 5 - 20 nm in length) morphologies. The sensing films were prepared by spin coating onto the Al2O3 substrates interdigitated with Au electrodes. The sensing films were significantly developed in order to detect with H2S (0.5 - 10 ppm) and SO2 (20 - 500 ppm) at the operating temperature ranging from 200 - 350°C. After sensing test, the cross-section of sensing film was analyzed by SEM analyses. It was found that SnO2 sensing film showed higher sensitive to H2S gas with very fast response at lower concentrations (3 s, to 10 ppm). The cross sensitivities of the sensor towards different concentrations of H2S, CO, H2, and C2H2 were measured at 300°C. The sensor evidently shows much less response to CO, H2, and C2H2 than to H2S indicating higher selectivity for H2S of the SnO2 sensor at the lower concentration (10 ppm). In addition, the SnO2 sensor was the most suitable candidate for the efficient detection of H2S noxious gas

H2-Sensing Performance of 2D WO3 Nanostructure—Effect of Anodization Parameter

In this work, we investigate the effect of HNO3 anodizing solution concentration ranging from 1.5 to 3 M on H2-sensing performance of 2D WO3 nanostructures prepared by anodizing sputtered tungsten films. The thickness of WO3 nanosheets was found to reduce while the crystallinity degraded with increasing HNO3 concentration. However, the nanosheets anodized in 2 M HNO3 exhibited the highest response of 43.4 to 1 vol % H2, which was one order of magnitude larger than those fabricated with other concentrations at the optimal operating temperature of 350 °C. In addition, the optimal nanostructures displayed good H2 selectivity against NO2, CH4, C2H2 and C2H5OH

3D Graphene-Carbon Nanotubes-Polydimethyl Siloxane Flexible Electrodes for Simultaneous Electrochemical Detections of Hg, Pb and Cd

In this work, the effect of CNTs content in 3D graphene-PDMS-CNTs electrodes were systematically studied for simultaneous determination of Hg, Pb and Cd by differential pulse anodic stripping voltammetry. The composites were formed by dip coating CVD graphene on Ni foam in CNTs-dispersed PDMS solution with varying CNTs concentrations. The optimal CNTs content was found to be ~0.5 mg/mL for all analytes. The optimal graphene-PDMS-CNTs electrode showed good analytical performances with sharp well-separated peaks of Pb, Hg and Cd in the concentration range of 100–500 μg/L. Therefore, the graphene-PDMS-CNTs electrode is highly promising for multiple detections of heavy metal pollutants

GO/2D WS2 Based Humidity Sensor

In this work, 2D WS2 nanosheets prepared by the exfoliation of WS2 with Li-intercalation was combined with GO produced by the Hummer method for humidity sensing applications. The GO and WS2 solutions were mixed with an equal concentration and coated on conductometric transducers. Sensing measurements towards humidity (0–80% RH) at room temperature revealed that the humidity response of hybrid was substantially higher by a factor of 3–9 depending on the RH value compared with those of GO and WS2. Moreover, no cross sensitivity to common gaseous compounds was observed. Therefore, the GO/2D WS2 composite is a highly promising humidity sensor