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Hierarchical Au-Loaded WO3 Hollow Microspheres with High Sensitive and Selective Properties to Toluene and Xylene
摘要： Functionalization of metal-oxide semiconductors by noble metal nanoparticles is one of the most efficient methods for enhancing the gas-sensing property of semiconducting sensors. Herein, we synthesized a series of Au-loaded hierarchical WO3 hollow microspheres (Au-WO3) via a facile modified solvothermal method combining with wet impregnation method. The structure, elemental composition and morphology of the synthesized materials were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results show that the materials are uniform and independent WO3 hollow microspheres, and Au nanoparticles are well distributed on the surface of WO3. The gas sensing properties of Au-WO3 materials were investigated and the results suggest that Au loading could greatly improve gas sensing performance of WO3 to aromatic compounds, especially toluene and xylene. Among the samples with different Au loading content, the one with 1.5 wt% Au (G3) exhibits the highest responses toward toluene and xylene at 340 °C. Moreover, the G3 sensor presents good responses, short response/recovery time, excellent selectivity, good reproducibility and long-term stability to toluene and xylene. Excellent gas sensing properties of Au-WO3 material make it a good candidate for detecting toluene and xylene.
关键词： toluene,Au-WO3,selectivity,xylene
更新于2025-11-14 17:03:37
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Photocatalytic oxidation of gaseous benzene, toluene and xylene under UV and visible irradiation over Mn-doped TiO2 nanoparticles
摘要： The photocatalytic oxidation of gaseous benzene, toluene and xylene (BTX) over un-doped, 0.1 and 1 wt% Mn-TiO2 nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas. The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy. BTX underwent efficient decomposition over Mn-TiO2 photocatalysts under UV irradiation, more with oxygen presence and less without oxygen. More important toluene and xylene went substantial decomposition over 0.1 mol% Mn-TiO2 under visible irradiation with oxygen presence. The main final oxidation products in the UV photocatalysis of BTX were CO2, CO and H2O, with CO2 and CO yields 4 and 2 respectively. The conversion percentage of benzene, toluene, and xylene to CO2 were 63.6%, 56.4%, 51.8%, and to CO 29%, 26.5%, 23.2%, respectively. In the visible photocatalysis of toluene and xylene the yields of CO were insignificant. Formation of carbon containing deposits on TiO2 surfaces was observed after extensive UV photocatalysis of toluene and xylene, and such by-products surface coverage may reduce the photocatalytic activity of TiO2 samples. Some aspects of the photocatalytic mechanism were examined.
关键词： Mn-doped TiO2,Visible - light photocatalysis,Photodegradation of Benzene,Indoors air pollution,Xylene,Toluene
更新于2025-09-23 15:23:52
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Highly selective and sensitive xylene gas sensor fabricated from NiO/NiCr2O4 p-p nanoparticles
摘要： Xylene is a harmful and hazardous volatile organic compound (VOC) indoors, thus selective and sensitive detection for subppm-level xylene is crucial, however a remained challenge. In this work, p-NiO/p-NiCr2O4 nanocomposites were successfully synthesized through a simple hydrothermal route and used as sensing materials. In the comparative gas sensing test, the sensor fabricated from NiO/NiCr2O4 (Cr/Ni=25 at%) nanocomposite exhibited the highest response (66.2-100 ppm) to xylene, which was 37.2 times higher than that of the pure NiO sensor. Moreover, the NiO/NiCr2O4 nanocomposite gas sensor showed not only superior xylene selectivity with low cross-responses to interfering gases such as ethanol (Sxylene/Sethanol =11.8) and acetone (Sxylene/Sacetone =10.2) but also ppb-level detection limit (1.2-50 ppb xylene) at 225 °C. The synergistic catalytic effect between NiO and NiCr2O4, optimized structural parameters and marked resistive variation due to the formation of nanoscale p-p heterojunctions were regarded as the main reasons for the ultrasensitive and selective xylene detection.
关键词： selectivity,xylene detection,heterojunction,gas sensor,NiO/NiCr2O4
更新于2025-09-23 15:23:52
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Physisorption induced p-xylene gas-sensing performance of (C4H9NH3)2PbI4 layered perovskite
摘要： A novel organic-inorganic layered perovskite compound (C4H9NH3)2PbI4 has been synthesized through a simple and high-yield solution method. For the first time, this layered perovskite was used as a candidate material for gas sensors. Gas sensors based on (C4H9NH3)2PbI4 provided unique gas-sensing properties toward 1 - 800 ppm p-xylene (p-C8H10) at the working temperature of 140 °C, including fast response, quick response-recovery, good selectivity and repeatability. The as-prepared (C4H9NH3)2PbI4 gas sensor can detect as low as 1 ppm concentration of p-xylene with a response of 11.8 at 140 °C. In situ diffuse reflectance Fourier transform infrared (DRFTIR) measurement shows that the p-xylene sensing mechanism can be mainly attributed to physical adsorption, which is different from other common gas-sensing metal oxides that are based on adsorption-redox-desorption mechanism.
关键词： (C4H9NH3)2PbI4,physisorption,layered perovskite,gas sensor,organic-inorganic,p-xylene
更新于2025-09-10 09:29:36
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Enhanced Sensing Performance to Toluene and Xylene by Constructing NiGa2O4-NiO Heterostructures
摘要： The selective detection of methyl benzene (e.g. toluene and xylene) using oxide semiconductor-based gas/vapor sensors is highly desirable but limited by the low chemical reactivity of the benzene compounds. Exploiting p-type semiconductor oxides (e.g., NiO) which provide distinctive catalytic activities for methyl benzene detection is an essential approach. However, the intrinsic responses of p-type semiconductor oxides are often low. In this paper, high-performance toluene and xylene detection has been realized by a sensor based on novel p-p heterojunction NiGa2O4-NiO nanospheres. Construction of optimized p-p heterojunctions, which resulting from the rationally controlling of the NiGa2O4 content in NiGa2O4-NiO, leads to significantly promoted sensing properties for toluene and xylene detection. It is found that the sensor based on 50% NiGa2O4-NiO exhibits the best sensing performances. Its highest response (Rg/Ra = 12.7 to toluene; Rg/Ra = 16.3 to xylene) is almost 10 times higher than that of the pure NiO (Rg/Ra < 2) to 100 ppm toluene and xylene at 230 oC. More importantly, the sensor exhibits superior selectively for detection of the methyl benzene even against more reactive interfering gases/vapors, such as formaldehyde and ethanol. The p-p oxide heterojunction suggests a promising sensing material for toluene and xylene detection with high response, excellent selectivity, good stability and rapid response/recover time.
关键词： Composite semiconductor,NiO,NiGa2O4,Heterojunction,Xylene,Toluene
更新于2025-09-10 09:29:36
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Pure and M-doped (M=Zn, Cu, Ni, Co) cadmium oxide nanosheets, novel adsorbents for the adsorption of ethyl benzene and ortho, meta, para xylene: a theoretical study
摘要： The electronic and structural properties investigation of pure and zinc, copper, nickel, cobalt doped cadmium oxide nanosheets (CdONS) and the adsorption of ethyl benzene (EB) and ortho- meta- para xylene (OX, MX, PX) on these nanosheets were studied by density functional theory calculations. The adsorption energy, charge transfer, energy gap, spatial distribution of HOMO and LUMO orbitals and electron density scheme of ethyl benzene and ortho, meta, para xylene molecules on pure and doped CdONS are calculated. The obtained results show that the adsorption energy value increases after doping Zn, Cu, Ni and Co atoms in oxygen substituted state, especially in NiOCdONS and CoOCdONS. The adsorption energy of EB, OX, MX and PX on NiOCdONS and CoOCdONS is about ? 260?kJ/mol whereas its value on pure CdONS is approximately ? 100?kJ/mol. In comparison with pure CdONS, the adsorption energy of the molecules on MCdCdONS, decreases except in NiCdCdONS. The adsorption energy of OX, MX and PX on NiCdCdONS is ? 263.12, ? 150.94 and ? 151.85?kJ/mol, respectively. Also, the results show that the value of energy gap increases after the adsorption of EB, OX, MX and PX on CoOCdONS, therefore, CoOCdONS can be proposed as proper adsorbent and sensor for these molecules.
关键词： Adsorption,Ethyl benzene,Xylene,Cadmium oxide nanosheet,Density functional theory
更新于2025-09-10 09:29:36
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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Quantitative Analysis of Xylene Mixtures Using a Handheld Raman Spectrometer
摘要： Xylene isomers (meta-xylene, ortho-xylene, and para-xylene) have been extensively analyzed by different instrumental methods. In this chapter, xylene isomers and their mixtures were analyzed qualitatively and quantitatively by Raman spectroscopy. First, we identified peaks that discriminated each isomer along with peaks that remain unchanged regardless of isomeric form. We used theoretical calculations to aid in the peak assignments. Then, we tested the efficacy of the technique in qualitatively and quantitatively apportioning isomeric mixtures of xylenes.
关键词： Xylene isomers,DFT calculations,Raman spectroscopy,quantitative analysis,handheld Raman spectrometer
更新于2025-09-04 15:30:14