Abstract:A titania-free heterostructure based on CuS/SnO2/WO3 was obtained by a three-step sol–gel method followed by spray deposition on the glass substrate. The samples exhibit crystalline structures and homogenous composition. The WO3 single-component sample morphology consists of fibers that serve as the substrate for SnO2 development. The CuS/SnO2/WO3 heterostructure is characterized by a dense granular morphology. Photocatalytic activity was evaluated under UV–Vis radiation and indicates that the WO3 single-compo… Show more
“…An interesting correlation emerges where increases in the Au concentration, calcination duration, and calcination temperature reduce the band gap energy. These measured band gap energies correspond closely with values reported in previous studies, demonstrating a consistent pattern with our work. – The reduction of band gap can be elucidated by the presence of intermediate states within the conduction and valence bands of the WO 3 host structure. The reduction in band gap energy can be explicated through the introduction of intermediary energy states within the conduction and valence bands of the host matrix with additional Au.…”
As a common environmental pollutant and an important breath biomarker for several diseases, it is essential to develop a hydrogen sulfide gas sensor with a low-ppb level detection limit to prevent harmful gas exposure and allow early diagnoses of diseases in lowresource settings. Gold doped/decorated tungsten trioxide (Au-WO 3 ) nanofibers with various compositions and crystallinities were synthesized to optimize H 2 S-sensing performance. Systematically experimental results demonstrated the ability to detect 1 ppb H 2 S with a response value (R air /R gas ) of 2.01 using a 5 at % Au-WO 3 nanofibers with average grain sizes of around 15 nm. Additionally, energy barrier difference of sensing materials in air and nitrogen (ΔE b ) and power law exponent (n) were determined to be 0.36 eV and 0.7, respectively, at 450 °C indicating that O − is predominately ionic oxygen species and adsorption of O − significantly altered the Schottky barrier between the grain. Such quantitative analysis provides a comprehensive understanding of H 2 S detection mechanism.
“…An interesting correlation emerges where increases in the Au concentration, calcination duration, and calcination temperature reduce the band gap energy. These measured band gap energies correspond closely with values reported in previous studies, demonstrating a consistent pattern with our work. – The reduction of band gap can be elucidated by the presence of intermediate states within the conduction and valence bands of the WO 3 host structure. The reduction in band gap energy can be explicated through the introduction of intermediary energy states within the conduction and valence bands of the host matrix with additional Au.…”
As a common environmental pollutant and an important breath biomarker for several diseases, it is essential to develop a hydrogen sulfide gas sensor with a low-ppb level detection limit to prevent harmful gas exposure and allow early diagnoses of diseases in lowresource settings. Gold doped/decorated tungsten trioxide (Au-WO 3 ) nanofibers with various compositions and crystallinities were synthesized to optimize H 2 S-sensing performance. Systematically experimental results demonstrated the ability to detect 1 ppb H 2 S with a response value (R air /R gas ) of 2.01 using a 5 at % Au-WO 3 nanofibers with average grain sizes of around 15 nm. Additionally, energy barrier difference of sensing materials in air and nitrogen (ΔE b ) and power law exponent (n) were determined to be 0.36 eV and 0.7, respectively, at 450 °C indicating that O − is predominately ionic oxygen species and adsorption of O − significantly altered the Schottky barrier between the grain. Such quantitative analysis provides a comprehensive understanding of H 2 S detection mechanism.
“…Therefore, the methods of formaldehyde detection and removal have attracted extensive attention from governments and scholars. Currently, the main ways to deal with formaldehyde are physical adsorption, photocatalytic degradation and biodegradation [3,4]. The traditional adsorption technology has a low adsorption capacity, and this shortcoming is especially obvious when the concentration of formaldehyde is low [5].…”
Release of formaldehyde gas indoors is a serious threat to human health. The traditional adsorption method is not stable enough for formaldehyde removal. Photocatalytic degradation of formaldehyde is effective and rapid, but photocatalysts are generally expensive and not easy to recycle. In this paper, geopolymer microspheres were applied as matrix materials for photocatalysts loading to degrade formaldehyde. Geopolymer microspheres were prepared from red mud and granulated blast furnace slag as raw materials by alkali activation. When the red mud doping was 50%, the concentration of NaOH solution was 6 mol/L, and the additive amount was 30 mL, the prepared geopolymer microspheres possessed good morphological characteristics and a large specific surface area of 38.80 m2/g. With the loading of BiOX (X = Cl, Br, I) photocatalysts on the surface of geopolymer microspheres, 85.71% of formaldehyde gas were adsorbed within 60 min. The formaldehyde degradation rate of the geopolymer microspheres loaded with BiOI reached 87.46% within 180 min, which was 23.07% higher than that of the microspheres loaded with BiOBr, and 50.50% higher than that of the microspheres loaded with BiOCl. While ensuring the efficient degradation of formaldehyde, the BiOX (X = Cl, Br, I)-loaded geopolymer microspheres are easy to recycle and can save space. This work not only promotes the resource utilization of red mud and granulated blast furnace slag, but also provides a new idea on the formation of catalysts in the process of photocatalytic degradation of formaldehyde.
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