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Halloysite based nanocomposites and photocatalysis: A Review
摘要： Heterogeneous photocatalysis is an e?cient, relatively cheap and environmentally friendly technology for decomposing various organic and air pollutants. Halloysite is a natural clay mineral usually in the form of nanotubes that has many applications as well as potential uses including photocatalysis. In this paper the photocatalytic activities of halloysite-based nanocomposites in combination with various photocatalysts that have been synthesized and tested in decomposing organic and air pollutants are reviewed. Many photocatalysts have been synthesized and among them TiO2 in the form of anatase, or rutile, or a mixture of both is the most common photocatalyst due to its e?ectiveness and low cost. Researches by many investigators are summarized and discussed. The possibilities and limitations of halloysite-based nanocomposites for future applications are also discussed and new ?elds of research are proposed. It is suggested that Halloysite-based nanocomposites are more promising in positively charged organic substrates like tetracycline and Rhodamine B where the organic pollutant is attracted by halloysite's negatively charged external surfaces close to the photocatalysts, than neutral like paracetamol or negatively charged which that attraction does not occur.
关键词： Azo dyes,Halloysite nanocomposite,Halloysite,TiO2,VOCs,Heterogeneous catalysis,Air pollutants,Photocatalysis
更新于2025-09-09 09:28:46
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Non-Invasive Diagnosis of Diabetes by Volatile Organic Compounds in Urine Using FAIMS and Fox4000 Electronic Nose
摘要： The electronic nose (eNose) is an instrument designed to mimic the human olfactory system. Usage of eNose in medical applications is more popular than ever, due to its low costs and non-invasive nature. The eNose sniffs the gases and vapours that emanate from human waste (urine, breath, and stool) for the diagnosis of variety of diseases. Diabetes mellitus type 2 (DM2) affects 8.3% of adults in the world, with 43% being underdiagnosed, resulting in 4.9 million deaths per year. In this study, we investigated the potential of urinary volatile organic compounds (VOCs) as novel non-invasive diagnostic biomarker for diabetes. In addition, we investigated the influence of sample age on the diagnostic accuracy of urinary VOCs. We analysed 140 urine samples (73 DM2, 67 healthy) with Field-Asymmetric Ion Mobility Spectrometry (FAIMS); a type of eNose; and FOX 4000 (AlphaM.O.S, Toulouse, France). Urine samples were collected at UHCW NHS Trust clinics over 4 years and stored at ?80 ?C within two hours of collection. Four different classifiers were used for classification, specifically Sparse Logistic Regression, Random Forest, Gaussian Process, and Support Vector on both FAIMS and FOX4000. Both eNoses showed their capability of diagnosing DM2 from controls and the effect of sample age on the discrimination. FAIMS samples were analysed for all samples aged 0–4 years (AUC: 88%, sensitivity: 87%, specificity: 82%) and then sub group samples aged less than a year (AUC (Area Under the Curve): 94%, Sensitivity: 92%, specificity: 100%). FOX4000 samples were analysed for all samples aged 0–4 years (AUC: 85%, sensitivity: 77%, specificity: 85%) and a sub group samples aged less than 18 months: (AUC: 94%, sensitivity: 90%, specificity: 89%). We demonstrated that FAIMS and FOX 4000 eNoses can discriminate DM2 from controls using urinary VOCs. In addition, we showed that urine sample age affects discriminative accuracy.
关键词： biosensor,urine sample,medical application,electronic nose,non-invasive diagnosis,FOX 4000,volatile organic compounds (VOCs),FAIMS,diabetes
更新于2025-09-09 09:28:46
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Adsorption mechanism of typical oxygen, sulfur, and chlorine containing VOCs on TiO2 (0?0?1) surface: First principle calculations
摘要： The photocatalytic degradation of volatile organic compounds has been gaining much interest in recent years to solve the long-standing problem of indoor air pollution. For this purpose, anatase TiO2 and its derivatives are regarded as potential photocatalyst materials. Thus, we study the adsorption mechanism of selected volatile organic compounds such as formaldehyde, methyl chloride, and carbon disulfide on TiO2 (0 0 1) surface using first principle calculations to comprehend their surface interaction and catalytic degradation in depth. The study suggests that formaldehyde interacts with TiO2 (0 0 1) surface through chemical bonds that form a saddle-like structure exhibiting a high adsorption energy value (0.543 eV). It can be inferred that the fivefold coordinated Ti5c and twofold coordinated O2c atoms are the only adsorption sites on TiO2 (0 0 1) surface. However, significant variations are observed for chloride and sulfur containing groups. For instance, the methyl chloride and carbon disulfide physisorbed on the surface of TiO2 (0 0 1) without any chemical bond formation exhibits low adsorption energy values. The results are further confirmed by calculating the corresponding density of states, and electron density differences in all cases. This study provides a detailed investigation of various VOCs on the surface of TiO2 (0 0 1), which provides further insight into the construction of photocatalytic materials for the photodegradation of VOCs.
关键词： Methyl chloride,TiO2 (0 0 1) surface,Formaldehyde,VOCs,DFT
更新于2025-09-09 09:28:46
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Organic field effect transistors (OFETs) in environmental sensing and health monitoring: A review
摘要： Organic field effect transistors (OFETs) have been the focus of sensing application research over the last two decades. In comparison to their inorganic counterparts, OFETs have multiple advantages, such as low-cost manufacturing, large area coverage, flexibility and readily tunable electronic material properties. To date, various organic semiconductors (OSCs), both polymers and small molecules, have been extensively researched for the purpose of developing the active channel layers in OFETs, enhancing their sensitivity and selectivity. However, OFET devices still need to be optimized to demonstrate reliable performance at the device level and in sensing applications. This review begins with an introduction of the OFETs with an emphasis on their geometry, materials (OSCs), fabrication process, and data analysis. After this, multiple applications are discussed and the progress regarding sensing elements and precisions is highlighted. In the end, the challenges and possible future directions of OFET arrays in embedded sensing platforms are presented.
关键词： stability,bi-layer,selectivity,biosensor,sensitivity,composites,OFETs,gamma irradiation,VOCs
更新于2025-09-09 09:28:46
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In situ fabrication of α-Fe2O3/CaFe2O4 p-n heterojunction with enhanced VOCs photodegradation activity
摘要： a-Fe2O3/CaFe2O4 p-n heterojunctions were prepared via a simple in-situ hydrolysis process as highly ef?cient VOCs degradation photocatalyst, wherein no additional conditions such as high pressure, high temperature and surfactants were required. The structures and morphologies of the as-prepared samples were analyzed by XRD, SEM and TEM. The results revealed that a-Fe2O3/CaFe2O4 p-n heterojunctions exhibited superior photocatalytic activity of VOCs degradation compared to pure CaFe2O4 and a-Fe2O3 in both steady model and ?ow bed model. It can degrade more than 82% of acetaldehyde within 180 min in steady mode and 65% in ?ow mode under visible light irradiation. The prominent VOCs remove property could be attributed to the strong interfacial contact caused by the in-situ fabrication process and the promoted charge carrier separation ef?ciency due to the constructing of a-Fe2O3/CaFe2O4 p-n heterojunction. It provides some new insights into the design and fabrication of advanced photocatalytic materials with p-n heterojunction for high ef?ciency in VOCs photodegradation.
关键词： VOCs photodegradation,In-situ fabrication,a-Fe2O3/CaFe2O4,p-n Heterojunction
更新于2025-09-04 15:30:14
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Intrinsically Porous Dual-Responsive Polydiacetylenes Based on Tetrahedral Diacetylenes
摘要： The combinatorial functionalization in a single molecular framework by structural integration utilizing multiple functional materials to create prede?ned structural morphology and multistimuli-responsive smart materials has attracted intensive attention. Herein, we constructed intrinsically porous and dual-responsive supramolecule, TeDA, by introducing a photopolymerizable diacetylene template (10,12-pentacosadiynoic acid) to the sterically rigid tetrahedral tetraphenylmethane (TPM) core. The self-assembled monomeric TeDA is transformed into the covalently cross-linked blue-phase polydiacetylene (TePDA) by UV irradiation (UV 254 nm). The BET measurement and examination of SEM images con?rm the mesoporous characteristic for TeDA/PDA. Very interestingly, the blue-phase TePDA produces a naked-eye detectable colorimetric response to heat and VOCs (liquid and vapor phase). Most importantly, TePDA exhibits reversible thermochromism and excellent colorimetric response to chloroform vapors. To signify the structural in?uence of TPM on material properties, we also studied non-TPM derivatives. The TeDA/PDA integrated system demonstrates potential applications in developing multistimuli-responsive sensors.
关键词： dual-responsive,porous,thermochromism,VOCs detection,colorimetric response,polydiacetylenes,tetrahedral diacetylenes
更新于2025-09-04 15:30:14