Aerosol-Assisted CVD-Grown PdO Nanoparticle-Decorated Tungsten Oxide Nanoneedles Extremely Sensitive and Selective to Hydrogen

We report for the first time the successful synthesis of palladium (Pd) nanoparticle (NP)-decorated tungsten trioxide (WO3) nanoneedles (NNs) via a two-step aerosol-assisted chemical vapor deposition approach. Morphological, structural, and elemental composition analysis revealed that a Pd(acac)2 precursor was very suitable to decorate WO3 NNs with uniform and well-dispersed PdO NPs. Gas-sensing results revealed that decoration with PdO NPs led to an ultrasensitive and selective hydrogen (H2) gas sensor (sensor response peaks at 1670 at 500 ppm of H2) with low operating temperature (150 °C). The response of decorated NNs is 755 times higher than that of bare WO3 NNs. Additionally, at a temperature near that of the ambient temperature (50 °C), the response of this sensor toward the same concentration of H2 was 23, which is higher than that of some promising sensors reported in the literature. Finally, humidity measurements showed that PdO/WO3 sensors displayed low-cross-sensitivity toward water vapor, compared to bare WO3 sensors. The addition of PdO NPs helps to minimize the effect of ambient humidity on the sensor response

Cobalt or Silver Doped WO3 Nanowires Deposited by a Two-Step AACVD for Gas Sensing Applications

A two-step procedure was implemented to obtain tungsten oxide nanowires (WO3) doped with cobalt or silver oxide nanoparticles from metal-organic precursors, W(CO)6, Co(acac)2 and Ag(acac)2. In the first step, nanowires were grown at 400 °C using an aerosol assisted chemical vapor deposition system (AA-CVD) and subsequently annealed at 500 °C for 2 h. In the second step, metal loading (at different doping levels) of the nanowires using the same system. These hybrid nanomaterials were grown on top of commercial alumina substrates that comprised interdigitated electrodes. The response of these nanomaterials toward H2S and H2 is investigated and discussed

p-Type PdO nanoparticles supported on n-type WO3 nanoneedles for hydrogen sensing

9th International Workshop on Semiconductor Gas Sensors (SGS), Zakopane, POLAND, SEP 13-16, 2016International audienceWe report the synthesis of palladium nanopartide (NP) decorated WO3 nanoneedles (NNs) employing a singlestep, aerosol assisted chemical vapor deposition approach. Two different Pd precursors were investigated in view of optimizing the morphology and the gas sensing performance of the resulting nanostructured films. In particular, palladium acetylacetonate was found to be more suitable than ammonium hexachloropalladate for obtaining n-type WO3 NNs uniformly decorated with well dispersed p-type PdO NPs. The active films could be directly deposited on the electrode area of microelectromechanical system-based resistive transducers. The morphology and chemical composition of the films was investigated by scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy analysis. PdO-decorated WO3 NNs show a response toward hydrogen that is about 680 times higher than that of bare WO3 NNs. Finally, PdO-loaded sensors display extremely low-cross sensitivity to water vapor, which makes them remarkably immune to changes in the background humidity. (C) 2016 Elsevier B.V. All rights reserved

Aerosol-Assisted CVD-Grown PdO Nanoparticle-Decorated Tungsten Oxide Nanoneedles Extremely Sensitive and Selective to Hydrogen

We report for the first time the successful synthesis of palladium (Pd) nanoparticle (NP)-decorated tungsten trioxide (WO₃) nanoneedles (NNs) via a two-step aerosol-assisted chemical vapor deposition approach. Morphological, structural, and elemental composition analysis revealed that a Pd­(acac)₂ precursor was very suitable to decorate WO₃ NNs with uniform and well-dispersed PdO NPs. Gas-sensing results revealed that decoration with PdO NPs led to an ultrasensitive and selective hydrogen (H₂) gas sensor (sensor response peaks at 1670 at 500 ppm of H₂) with low operating temperature (150 °C). The response of decorated NNs is 755 times higher than that of bare WO₃ NNs. Additionally, at a temperature near that of the ambient temperature (50 °C), the response of this sensor toward the same concentration of H₂ was 23, which is higher than that of some promising sensors reported in the literature. Finally, humidity measurements showed that PdO/WO₃ sensors displayed low-cross-sensitivity toward water vapor, compared to bare WO₃ sensors. The addition of PdO NPs helps to minimize the effect of ambient humidity on the sensor response

Radiocesium concentrations in wild boars captured within 20?km of the Fukushima Daiichi Nuclear Power Plant

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011 released large amounts of artificial radioactive substances into the environment. In this study, we measured the concentration of radiocesium (134Cs + 137Cs) in 213 muscle samples from wild boars (Sus scrofa) captured in Tomioka town, which is located within 20 km of the FDNPP. The results showed that 210 (98.6%) muscle samples still exceeded the regulatory radiocesium limit (100 Bq/kg) for general foods. Radiocesium (134Cs + 137Cs) levels ranged from 87.1?8,120 Bq/kg fresh mass (FM), with a median concentration of 450 Bq/kg FM. The median committed effective dose was estimated to be 0.070?0.26 μSv/day for females and 0.062?0.30 μSv/day for males. The committed effective dose for one-time ingestion of wild boar meat could be considered extremely low for residents in Tomioka. The relatively high levels of radioactivity found in this study suggest that the high variability of food sources may have led to the large accumulation of radioactive substances. These results suggest that comprehensive long-term monitoring is needed to identify risk factors affecting recovery from a nuclear disaster

Indoor air pollution, physical and comfort parameters related to schoolchildren's health: Data from the European SINPHONIE study

Substantial knowledge is available on the association of the indoor school environment and its effect among schoolchildren. In the same context, the SINPHONIE (School indoor pollution and health: Observatory network in Europe) conducted a study to collect data and determine the distribution of several indoor air pollutants (IAPs), physical and thermal parameters and their association with eye, skin, upper-, lower respiratory and systemic disorder symptoms during the previous three months. Finally, data from 115 schools in 54 European cities from 23 countries was collected and included 5175 schoolchildren using a harmonized and standardized protocol. The association between exposures and the health outcomes were examined using logistic regression models on individual indoor air pollutants (IAPs); a VOC (volatile organic compound) score defined as the sum of the number of pollutants to which the children were highly exposed (concentration > median of the distribution) in classroom was also introduced to evaluate the multiexposure – outcome association, while adjusting for several confounding factors. Schoolchildren exposed to above or equal median concentration of PM2.5, benzene, limonene, ozone and radon were at significantly higher odds of suffering from upper, lower airways, eye and systemic disorders. Increased odds were also observed for any symptom (sick school syndrome) among schoolchildren exposed to concentrations of limonene and ozone above median values. Furthermore, the risks for upper and lower airways and systemic disorders significantly increased with the VOCs score. Results also showed that increased ventilation rate was significantly associated with decreased odds of suffering from eye, skin disorders whereas similar association was observed between temperature and upper airways symptoms. The present study provides evidence that exposure to IAPs in schools is associated with allergic and respiratory symptoms in children. Further investigations are needed to confirm our findings. © 2020 Elsevier B.V