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Humidity sensing properties of metal organic framework-derived hollow ball-like TiO2 coated QCM sensor
摘要： This paper demonstrates three kinds of TiO2 with hollow ball, nanosphere, and nanoflower nanostructures coated quartz crystal microbalance (QCM) humidity sensors, which were synthesized by metal organic framework (MOF)-derived, hydrothermal and solvothermal route, respectively. The compositional and morphological characteristics of three kinds of TiO2 nanostructures were characterized by means of X-ray diffraction (XRD), specific surface area analysis (BET), scanning electron microscopy (SEM) and water contact angle measurement. We found that the surface structure plays a crucial role in the humidity-sensing response properties of QCM sensors. The humidity sensing experiment was performed at room temperature. The MOF-derived hollow ball-like TiO2 coated QCM sensor exhibited excellent humidity sensing characteristics over a wide RH range (0%-97%RH), such as high sensitivity (33.8 Hz/%RH), good repeatability and short dynamic response/recovery times (5 s/2 s). In addition, Langmuir adsorption model was developed to explain the humidity-sensing properties of the TiO2-based QCM sensor. This work proves that MOF-derived hollow-ball TiO2 is a potential candidate nanomaterial for humidity sensor fabrication.
关键词： humidity sensor,Langmuir adsorption model,quartz crystal microbalance,hollow ball-like TiO2
更新于2025-09-23 15:22:29
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Photo-refreshable electrochemical sensor based on composite electrode of carbon nanotubes and TiO2 nanoparticles
摘要： Surface fouling and passivation on the electrode during electrochemical process is a major challenge for the practical applications of electrochemical sensors. Herein, a photo-refreshable electrochemical sensor was presented based on carbon nanotubes/TiO2 nanoparticles (CNTs/TiO2-NPs) composite electrode, which not only exhibits high electrochemical activity towards the determination of 5-hydroxytryptamine and dopamine, but also displays excellent reproducibility in the surface electrochemical monitoring without damaging microstructure. The linear range for 5-hydroxytryptamine determination is 0.5-400 μM (R=0.991) under UV light irradiation with a detection limit of 0.47 μM (S/N=3). The CNTs/TiO2-NPs electrode also shows excellent response to dopamine, with the linear range of 0.05 μM to 100 μM and a detection limit of 0.022 μM (S/N =3). The high performance of this photo-refreshable electrochemical sensor should be attributed to the excellent photocatalytic activity of the TiO2-NPs and the high electrochemical activity of CNTs.
关键词： carbon nanotubes,photocatalysis,TiO2 nanoparticles,electrochemical sensors,surface fouling
更新于2025-09-23 15:22:29
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Preparation and Characterization of Polymer Composite Materials Based on PLA/TiO2 for Antibacterial Packaging
摘要： Polymer composite materials based on polylactic acid (PLA) filled with titanium dioxide (TiO2) nanoparticles were prepared. The aim of this work was to investigate the antibacterial action of TiO2 against a strain of E. coli (DH5α) to obtain information on their potential uses in food and agro-alimentary industry. PLA/TiO2 systems were prepared by a two-step process: Solvent casting followed by a hot-pressing step. Characterization was done as a function of particle size (21 nm and <100 nm) and particle content (0%, 1%, 5%, 10%, and 20%, wt %). Structural characterization carried out by X-ray diffraction (XRD) and Fourier Transformed Infrared spectroscopy (FTIR) did not reveal significant changes in polymer structure due to the presence of TiO2 nanoparticles. Thermal characterization indicated that thermal transitions, measured by differential scanning calorimetry (DSC), did not vary, irrespective of size or content, whereas thermogravimetric analysis (TGA) revealed a slight increase in the temperature of degradation with particle content. Bacterial growth and biofilm formation on the surface of the composites against DH5α Escherichia coli was studied. Results suggested that the presence of TiO2 nanoparticles decreases the amount of extracellular polymeric substance (EPS) and limits bacterial growth. The inhibition distances estimated with the Kirby-Bauer were doubled when 1% TiO2 nanoparticles were introduced in PLA, though no significant differences were obtained for higher contents in TiO2 NPs.
关键词： antibacterial packaging,polylactic acid (PLA),polymer nanocomposites,TiO2 nanoparticles
更新于2025-09-23 15:22:29
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Preparation and properties of Co3O4-doped TiO2 nanotube array electrodes
摘要： Co3O4-doped TiO2 nanotube array electrodes were prepared by anodizing the Co–Ti alloys with different Co contents. Morphologies, elemental compositions, crystal structures, and electrochemical properties of the samples were characterized through scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical workstation. The effects of Co content, annealing temperature and testing electrolyte on the electrochemical properties of the electrodes were studied. Results show that the areal capacitance values of TiO2 nanotube arrays were obviously improved by doping with Co3O4. The electrochemical properties of Co3O4-doped TiO2 nanotube array electrodes were best when the Co content in the alloys was 9%; the annealing temperature was 100 °C and the testing electrolyte was 0.5 M Na2SO4. The Co3O4-doped TiO2 nanotube array electrodes prepared under the optimal conditions had a high areal capacitance value of 937.9 μF cm?2 when the scan rate was 10 mV s?1 and the electrodes exhibited good rate and superior cycling performance.
关键词： Co–Ti alloys,Electrochemical properties,Co3O4,Anodization,TiO2 nanotube arrays
更新于2025-09-23 15:22:29
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Effect of defects in TiO2 nanoplates with exposed {001} facets on the gas sensing properties
摘要： The exposed crystal facet of TiO2 is a crucial factor influencing the gas sensing properties. TiO2 with high-energy {001} crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties. In this paper, TiO2 nanoplates with defective {001} facets were synthesized by chemical etching via one-step hydrothermal method. We carefully explored the gas-sensing performance of TiO2 nanoplates with defective and complete {001} facets towards acetone. The results show that the sensing response of TiO2 nanoplates with complete {001} facets is 70% higher than that of defective TiO2 nanoplates, which proves that the {001} facets plays a vital role in improving the gas sensing performance of TiO2. It is speculated that the poor gas sensitivity of defective TiO2 can be contributed to fewer adsorption sites and blocked electron transfer. This work presents a more direct evidence for explaining the important role of the complete {001} crystal facets in high sensitivity of TiO2 and also provides a new insight for preparing high sensitivity sensing materials.
关键词： TiO2 nanoplates,Defective,Acetone,{001} facets,Gas sensing
更新于2025-09-23 15:22:29
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Enhanced degradation of BPA in water by PANI supported Ag/TiO2 nanocomposite under UV and visible light
摘要： PANI supported Ag@TiO2 nanocomposite was synthesized via oxidative polymerization of aniline on Ag@TiO2. The Ag@TiO2 nanocomposite was synthesized by the photo reduction of Ag nanoparticles on hydrothermally synthesized TiO2 nanofibers. Raman analysis revealed that the anatase phase of TiO2 was synthesized showing typical peaks at 195 cm-1, 396 cm-1, 514 cm-1, and 637 cm-1. The incorporation of PANI, a carbonaceous material was confirmed by appearance of D-band and G-band in Ag@TiO2-PANI that were located at 1505 cm-1 and 1603 cm-1 respectively. X-ray diffraction (XRD) analysis confirmed the anatase phase of TiO2 was synthesized. Transmission electron microscopy analysis (TEM) analysis revealed that TiO2 nanofibers were synthesized successfully and Ag nanoparticles of different sizes were deposited on their surface. X-ray Photon Spectroscopy (XPS) survey scan of the Ag@TiO2-PANI-nanocomposite revealed that the nanocomposite was made from C, O, Ag, Ti, and N. DRS and Tauc`s plot estimated the band gap of Ag@TiO2-PANI to be 3.0 eV. A comparative study of the photocatalytic performance of Ag@TiO2-PANI catalyst showed better degradation performance under both conditions than pristine TiO2, and Ag@TiO2 with a degradation of up to 99.7% under visible light irradiation. The degradation experiments showed that the reactive species that were dominant in the degradation of BPA were h+ and .O2-. The nanocomposite was re-used to degrade BPA for up to four cycles without losing much of its photocatalytic ability with a removal of at least 90% in the fourth cycle.
关键词： Bisphenol A,Ag@TiO2-PANI,visible light,X-ray photoelectron spectroscopy,UV
更新于2025-09-23 15:22:29
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A Visible Light-Near-Infrared Dual-Band Smart Window with Internal Energy Storage
摘要： The integration of electrochromic smart windows with energy storage is an appealing concept for green building development. Herein, we report a dual-band electrochromic energy storage (DEES) window capable of independent control of visible light (VIS) and near-infrared (NIR, solar heat) transmittance with a high internal charge storage. The key design feature is the use of composition-optimized Ta-doped nano-TiO2 nanocrystals as a multifunctional active material to deliver a high charge-storage capability concurrently with high bistability and long-cycle-life electrochromism in three distinct operating modes: (1) the VIS and NIR transparent "bright" mode; (2) the VIS transparent and NIR opaque "cool" mode; and (3) the completely opaque "dark" mode. The independent control of VIS (sunlight) and NIR (solar heat) modulation was successfully demonstrated in a DEES prototype with a high charge-storage capacity of 466.5 mA hr m?2 at 150 mA m?2 of current density.
关键词： nanocrystals,dual-band electrochromic,smart window,energy storage,Ta-doped TiO2
更新于2025-09-23 15:22:29
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ZnO-based nanocomposites prepared by a vapor phase route, investigated by XPS
摘要： Nanostructured materials based on ZnO, eventually functionalized with titanium oxide (TiO2) or tungsten oxide (WO3), were fabricated on fluorine-doped tin oxide-coated glass substrates by a combined chemical vapor deposition/radio frequency-sputtering route. In particular, the present work focuses on the use of x-ray photoelectron and x-ray excited Auger electron spectroscopies for a detailed investigation of the system O 1s, Zn 2p3/2, Zn 3p, and Zn LMM core levels, as well as Ti 2p and W 4f photoelectron peaks. In a nutshell, the results of these analyses highlight the obtainment of pure ZnO nanodeposits, as well as of ZnO-TiO2 and ZnO-WO3 composites, in which the identity of each component is preserved, and the occurrence of an electronic interplay between ZnO and WO3 phases in the latter system.
关键词： RF-sputtering,CVD,x-ray photoelectron spectroscopy,WO3,TiO2,ZnO
更新于2025-09-23 15:22:29
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Enhanced UV emission of TiO <sub/>2</sub> –ZnO nanocomposite films synthesized by simplified sol–gel dip-coating method
摘要： TiO2–ZnO composite film was regarded as a promising candidate for UV emitter devices. For exploring a lower cost and convenient preparation method for highly efficient UV-emission TiO2–ZnO composite film, we used a simplified method in which mixing ZnO sol and TiO2 sol directly to prepare TiO2–ZnO nanocomposite films with a varied atomic ratio of Zn/(Ti + Zn) (TiO2, Z20, Z40, Z60, Z80, ZnO) on glass substrates and discussed its optical properties for the first time in this study. The photoluminescence (PL) spectra indicated that the UV emission of the composite films was greatly enhanced compared with that showed by single-phase TiO2 or ZnO film. In particular, the UV emission intensity of Z60 composite film was enhanced by a factor of 10 compared to that of single-phase ZnO or TiO2. The enhanced PL intensity of the composite films could be attributed to fluorescence resonance energy transfer (FRET).
关键词： TiO2–ZnO Nanocomposite Films,Optical Property,Simplified Sol–Gel Method,FRET
更新于2025-09-23 15:22:29
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TiO2 Modification with Transition Metallic Species (Cr, Co, Ni, and Cu) for Photocatalytic Abatement of Acetic Acid in Liquid Phase and Propene in Gas Phase
摘要： The commercial P25 titania has been modi?ed with transition metallic species (Cr, Co, Ni, and Cu), added by impregnation with aqueous solutions of the corresponding nitrates. The preparation procedure also includes a heat treatment (500 ?C) in argon to decompose the nitrates, remove impurities and to strengthen the metal–TiO2 interaction. The catalysts have been thoroughly characterized using N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse-re?ectance spectroscopy (UV-vis DRS) and X-ray photoelectron spectroscopy (XPS), and have been tested in the aqueous phase decomposition of acetic acid and in the gas phase oxidation of propene, using an irradiation source of 365 nm in both cases. The photocatalytic activity of the four metal-containing catalysts varies with the nature of the metallic species and follows a similar trend in the two tested reactions. The effect of the nature of the added metallic species is mainly based on the electrochemical properties of the supported species, being Cu/P25 (the sample that contains copper) the best performing catalyst. In the photodecomposition of acetic acid, all the metal-containing samples are more active than bare P25, while in the gas phase oxidation of propene, bare P25 is more active. This has been explained considering that the rate-determining steps are different in gas and liquid media.
关键词： TiO2,P25,propene,photocatalysis,acetic acid,transition metals
更新于2025-09-23 15:22:29