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How does cobalt phosphate modify the structure of TiO2 nanotube array photoanodes for solar water splitting?
摘要： TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 minutes. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 minutes, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) results, by depositing the electrocatalyst, nanotube walls have been spread and holes have been covered by CoPi. Correlation between observed change in surface morphology and Raman spectra of the samples along with electrocatalytic tests revealed how decoration time can influence structural properties and photoelectrochemical performance of the final CoPi/TNA photoanodes in solar water splitting system.
关键词： CoPi,TiO2 photoanode,photoelectrochemical performance,solar water splitting
更新于2025-09-09 09:28:46
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Nanotechnology in Water and Wastewater Treatment || Photocatalytic Decolorization of Two Remazol Dyes Using TiO2 Impregnated Pumice Composite as Catalyst
摘要： This study, as a first attempt, aimed to evaluate photocatalytic decolorization of of two remazol dyes (blue and red) using TiO2 impregnated pumice composite catalyst. The SEM-EDX analysis showed that TiO2 nanoparticules were mostly impregnated on the pores of pumice with a ratio of 1.60% Ti. A 97.8% and 97.6% of color removal was achieved for RB and RR at pH 3, respectively, whereas those color removal percentages decreased to 57.4% and 53.9%, respectively, at pH 11 after 2 hours illumination. The color removal efficiencies of 97.8%, 82.7%, and 75.3% for RB dye and of 97.6%, 85.3%, and 84.0% for RR dye were observed after first, second, and third cycles reuse of the synthesized catalyst. Toxicity of photocatalytic treated samples of both dyes decreased below 50% after 90 and 120 minutes irradiation when they were diluted at 75%. This result indicate there is an urgent need to prolong the irradiation time and/or for increasing catalyst dose to completely remove toxicity in the undiluted samples.
关键词： TiO2 impregnated pumice composite,Remazol dyes,Photocatalytic decolorization,Toxicity,UV-A illumination
更新于2025-09-09 09:28:46
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Surface enhanced Raman spectroscopy with methyl-orange on Ag-TiO2 nanocomposites: Experimental and theoretical investigation
摘要： Ag-TiO2 nanocomposites of different Ag nanoparticle (NP) concentrations are experimentally prepared and their UV-vis and surface enhanced Raman scattering characteristics are determined. The enhancement of the Raman signal for the ligand methyl-orange (MO) adsorbed onto the nanocomposite system, is observed. To investigate the influence of changing Ag concentration in this nanocomposite system, molecular dynamics (MD) simulations are conducted with both a fixed as well as varying number of the surfactant MO adsorbed onto the nanocomposite. Density functional theory (DFT) simulations are performed to investigate the conditions for charge transfer from the MO surfactant via the highest occupied molecular orbitals (HOMO), lowest unoccupied molecular orbitals (LUMO) as well as the electrostatic potentials. It is shown that the bonding mode of the surfactant contributes greatly to the observed Raman scattering enhancement.
关键词： HOMO-LUMO,Surface Enhanced Raman Scattering,density functional theory,molecular dynamics,Ag-TiO2 nanocomposite,electrostatic potential
更新于2025-09-09 09:28:46
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Quantum confinement chemistry of CdS QDs plus hot electron of Au over TiO2 nanowire protruding to be encouraging photocatalyst towards nitrophenol conversion and ciprofloxacin degradation
摘要： Solar light harvesting science is ascertained to be the topmost effective green technique in alleviating environmental pollutants. In this respect, we report a visible light active TiO2/Au/CdS QDs nanocomposite which manifested upgraded photocatalytic activity towards the transformation of 2-nitrophenol, 4-nitrophenol, and degradation of ciprofloxacin. Here, TiO2 nanowire is synthesized by a molten flux method with high product yield and crystallinity with organized dimensions. Au nanoparticles are successfully integrated in between TiO2-CdS composite by Reverse Turkevich method. The prepared composites are meticulously characterized by different physical and optoelectronic techniques to inspect the crystal structure, phase purity, optical properties, nanostructured morphology and electrochemical properties. The plasmonic direct hot electron transfer (DET) mechanism is confirmed from UV-Vis DRS spectra. The prepared composite produces 2.98 mA/cm2 of current density under light irradiation. A Longer lifetime of electrons is found from Bode phase plot i.e. 97.4 μs for TiO2/1%Au/3%CdS QDs owing to the integrative cooperation effect of high aspect ratio of TiO2 nanowire, quantum size effect of CdS and the direct hot electron transfer by Au nanoparticle.
关键词： TiO2 nanowire,2-nitrophenol,DET,4-nitrophenol,ciprofloxacin,CdS QDs
更新于2025-09-09 09:28:46
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Composition, Morphology, Structure and Photocatalytic Performances of Photocatalysts Prepared from Titanium Potassium Oxalate
摘要： In this work, different products were synthesized using potassium titanium oxalate as the precursor when the reaction conditions varied. The influences of reaction system conditions on the formation features, particle size, phase composition, morphology and properties of the products were investigated and discussed. The XRD and SEM results indicated that TiO2 with different morphology and particle size were prepared by a hydrothermal treatment of the reaction system including HCl and H2O2 solution, and its degradation rate reached 100% after 100 min under UV irradiation. However, under the conditions without H2O2, a new product C2O7Ti2·3H2O with a large crystal of hexagonal prism was synthesized. Photocatalytic degradation of methyl orange (MO) indicated that C2O7Ti2·3H2O exhibited high photocatalytic activity. And the results of the active species detection show that ?O2? was the main reactive species for MO degradation. The formation mechanism of the product prepared by different reaction system was also discussed.
关键词： Titanium potassium oxalate,Morphology control,Photocatalytic activity,C2O7Ti2·3H2O,TiO2
更新于2025-09-09 09:28:46
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ion bombardment effect on the band gap of anatase TiO2 ultrathin films
摘要： We report a study of the effect of nitrogen ion bombardment on the optical properties of anatase TiO2 ultrathin films, particularly the band gap energy. The TiO2 films were prepared by a sol-gel method and dip-coating process. The as-prepared TiO2 films were then exposed to a +N2 low-energy ion beam from a microwave electron cyclotron resonance (ESR) ion source. Raman and spectroscopic ellipsometry (SE) analysis were performed on TiO2 films prepared at different +N2 exposure times. The Raman measurements reveal the conservation of the anatase TiO2 crystalline structure after the ion beam exposure. From a detailed ellipsometric study, the thickness of layers, the dielectric function, the band gap and the Urbach energies were determined. The obtained results show an increase of the TiO2 band gap with the decrease of thickness of films during +N2 exposure time. The band gap energy was blue shifted from 20 meV to 140 meV as the exposure time was increased from 5 min to 20 min when the thickness was decreased from 30 nm to 21 nm. This increasing of band gap energy could be explained by the thickness effect. From the band tail, the Urbach energy was also affected by +N2 ion beam. These results are in good agreement with the observed broadending of the Raman band the OeTieO bending vibration mode, as the exposure time increases.
关键词： +N2 ion bombardment,TiO2,Urbach energy,Band gap energy,Raman,Ellipsometry
更新于2025-09-09 09:28:46
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Improved field emission from appropriately packed TiO2 nanorods: Designing the miniaturization
摘要： An improved electron field emission (FE) property from vertically aligned TiO2 nanorods (TNR) on conducting fluorine doped tin oxide coated glass substrate, prepared by hydrothermal technique, has been reported here. The TNRs having high aspect ratio with appropriate separation were prepared by optimizing the nucleation temperature. The TNR density has been optimized to cease the screening effect in closely packed nanorods. The well aligned rods have been designed so that the applied field is equally distributes on each rod to improve the electron emission. The morphology of the nanorod has been studied using scanning electron microscopy and observed FE current density-field response has been analysed within the frame work of Fowler-Nordheim modelling. Two orders of magnitude enhancement in the electric field has been observed for this kind of geometry giving improved turn on field and field enhancement factor of 0.2 V/m m and 37 thousands respectively.
关键词： Fowler-Nordheim modelling,Hydrothermal technique,Field emission,TiO2 nanorods,Field enhancement factor
更新于2025-09-09 09:28:46
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Novel photocatalytic system Fe-complex/TiO2 for efficient degradation of phenol and norfloxacin in water
摘要： Photocatalysis is one of the effective strategies to eliminate various organic pollutants in water body. In this paper we have prepared a series of new composite photocatalysts to degrade phenol and norfloxacin under visible light irradiation. They were [FeII(dpbpy)2(H2O)2]/TiO2, [FeII(dpbpy)(phen)2]/TiO2 and [FeII(dpbpy)(bpy)2]/TiO2 (dpbpy: 2,2′-bipyridine-4,4′-diphosphoric acid, phen: 1,10-phenanthroline, bpy: 2,2-bipyridyl). The results show that their photocatalytic performance and cyclic stability are much better than that of pure TiO2 or P25. Phenol can be degraded almost completely and the active groups or substituents of norfloxacin (NOR) can be destroyed also, which greatly reduced the biological toxicity of phenol and norfloxacin in water. The possible mechanisms of improving the photocatalytic activity and stability of TiO2 by using Fe-complex are proposed based on free radical capture test and density functional theory calculation. It is clearly that the interfacial interaction between Fe-complex and titanium dioxide directly affects the photocatalytic activity and stability of the composite photocatalyst. The conjugated structure of the complexes plays a crucial role.
关键词： Photocatalystic degradation under visible light,Phenol,Norfloxacin,Fe-complex/TiO2 composite
更新于2025-09-09 09:28:46
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TiO <sub/>2</sub> /zeolite Bifunctional (Photo)catalysts for a Selective Conversion of Methanol to Dimethoxymethane: On the Role of Br?nsted Acidity
摘要： In the present work, we report the first example of one-step selective methanol photooxidation to dimethoxymethane (DMM) at room temperature over TiO2/zeolite bifunctional catalysts. The effects of the porosity, basicity/acidity of the zeolites on the selectivity of the reaction are discussed. The role of TiO2 active sites and zeolitic Br?nsted acid sites on the DMM production is reported. As the photocatalytic reaction occurs at room temperature, the influence of the reaction temperature is also investigated to extrapolate the results to thermal catalysis. This study demonstrates a clear synergetic effect of the zeolites on the selectivity of the reaction. They can display an important impact on the selectivity of the photocatalytic reaction even at a low temperature (e.g. room temperature). Based on the obtained results, the reaction mechanism of methanol conversion to DMM is elucidated.
关键词： Br?nsted acidity,dimethoxymethane (DMM),selective conversion,methanol photooxidation,TiO2/zeolite bifunctional catalysts
更新于2025-09-09 09:28:46
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Elemental mercury removal from flue gas over TiO2 catalyst in an internal-illuminated honeycomb photoreactor
摘要： TiO2 catalyst in an internal-illuminated honeycomb photoreactor was prepared for Hg0 removal from flue gas. The Hg0 removal efficiency was above 95% under the optimal operation condition. With the increasing TiO2 coating value, the Hg0 removal efficiency significantly increased. The catalyst calcined at 400 oC presented optimal Hg0 removal performance, while higher calcination temperature weakened the Hg0 photocatalytic removal activity. Similar Hg0 removal performances were obtained under UV irradiation when the reaction temperature was in the range of 25-90 oC, and 1.5 mW/cm2 of UV light irradiation was competent for Hg0 photocatalytic removal. With the same quantity utilization of TiO2 catalyst, the internal-illuminated honeycomb photoreactor presented better Hg0 removal performance than fixed-bed reactor. Finally, the procedure of Hg removal from flue gas over TiO2 catalyst in internal-illuminated honeycomb photoreactor was proposed, and the product in the Hg0 photocatalytic removal process was analyzed as well.
关键词： mercury,coal combustion,TiO2,photocatalytic removal,photoreactor
更新于2025-09-09 09:28:46