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Photocatalytic oxidation of thiophene over cerium doped TiO2 thin film
摘要： Samples of TiO2 and TiO2 doped with 2% and 8% cerium ions were prepared by a sol-gel method and used as photocatalysts for the oxidation of vaporized thiophene. X-ray diffraction patterns showed a mixed phase of anatase and rutile for TiO2, while 2%Ce/TiO2 and 8%Ce/TiO2 were dominated by the anatase phase. As seen in the transmission electron microscopy image, the particle size of Ce/TiO2 was about 10 nm which was smaller than the undoped TiO2. The extended x-rays absorption fine structures revealed the substitutional effect of cerium in the TiO2 structure. Cerium-doped TiO2 exhibited a smaller photocurrent compared to that of TiO2, which suggested the electrons were trapped by cerium ions. In situ diffuse reflectance infrared spectroscopy under UV irradiation and x-ray photoemission spectroscopy were used to investigate the photocatalytic oxidation of thiophene on the prepared catalysts. Doping of cerium ions in TiO2 resulted in an enhanced adsorption of thiophene on the catalyst surface. The oxidation products of carboxylic acid with small amounts of sulfate ions were observed. As seen from the infrared absorption spectrum, 2%Ce/TiO2 and 8%Ce/TiO2 exhibited higher photocatalytic activity than those of the undoped TiO2.
关键词： Thiophene oxidation,Thin film,Cerium,Photocatalysis,Titanium dioxide
更新于2025-09-23 15:23:52
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Diversity of TiO <sub/>2</sub> : Controlling the Molecular and Electronic Structure of Atomic-Layer-Deposited Black TiO <sub/>2</sub>
摘要： Visually black, electrically leaky, amorphous titania (am-TiO2) thin films were grown by atomic layer deposition (ALD) for photocatalytic applications. Broad spectral absorbance in the visible range and exceptional conductivity are attributed to trapped Ti3+ in the film. Oxidation of Ti3+ upon heat treatment leads to a drop in conductivity, a color change from black to white and crystallization of am-TiO2. ALD grown black TiO2, without any heat treatment, is subject to dissolution in alkaline photoelectrochemical conditions. The best photocatalytic activity for solar water splitting is obtained for completely crystalline white TiO2.
关键词： atomic layer deposition,photocatalysis,titanium dioxide,protecting overlayers,crystallization,oxide defects,water splitting
更新于2025-09-23 15:23:52
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Hydration accelerator and photocatalyst of nanotitanium dioxide synthesized via surfactant-assisted method in cement mortar
摘要： To develop TiO2-based cement materials, the effect of TiO2 on the cement hydration and photocatalytic reaction should be investigated. The phase, size and shape of TiO2 are important factors for better understanding its application in cement. TiO2 nanoparticles were synthesized by a surfactant-assisted, reverse micelle method to control phase, size and shape by three selected surfactants namely: sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and TritonX-100. The synthesized TiO2 nanoparticles were characterized by XRD, SEM and TEM for observation of phase, size and shape. The modified micro structures of admixed cements with the different synthesized TiO2 nanoparticles incorporated were also examined by SEM. Particularly, the hydration process and photocatalytic reaction of the cement mixture were evaluated by heat flow calorimetry and methylene blue (MB) degradation, respectively. Results showed that anatase-rich and smaller size TiO2 nanoparticles provided accelerated cement hydration and the ability to degrade MB photocatalytically at the surface of admixed-TiO2 cement.
关键词： Surfactant-assisted method,Photocatalytic activity,Hydration,Cement,Titanium dioxide nanoparticle
更新于2025-09-23 15:22:29
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The cost-effective deposition of ultra-thin titanium(IV) oxide passivating layers for improving photoelectrochemical activity of SnS electrodes
摘要： The structures of tin monosulfide (SnS) with the surface modified by ultrathin titanium(IV) oxide layers for potential photoinduced water splitting were successfully fabricated. SnS thin films were deposited onto glass/Mo substrates using high vacuum evaporation (HVE) method, and then a simple and cost-effective deposition-annealing cycling process was used to prepare titanium(IV) oxide passivated SnS structures. The resulting compositional properties were studied using X-ray diffractometry (XRD), Raman spectroscopy, high resolution scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The effects of titanium(IV) oxide layers on the photo-electrochemical (PEC) activity of fabricated p-type SnS thin-film electrodes were examined in this study. The SnS layers passivated with titanium(IV) oxide exhibited reducing the SnS-electrolyte interface resistance, increasing the photocurrent and improving the efficiency of PEC cells as deleterious reactions are inhibited. The various electrochemical methods such as current-voltage measurements, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterise and analyse SnS structures modified by titanium(IV) oxide.
关键词： Photocathode,Solar energy,Tin sulfide,Titanium dioxide,Water splitting
更新于2025-09-23 15:22:29
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Synthesis of a novel visible light responsive <i>γ</i> -Fe2O3/SiO2/C-TiO2 magnetic nanocomposite for water treatment
摘要： This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by FTIR, XRD, TEM and EDS substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15–22 nm with a quasi-spherical shape. BET surface area analysis revealed an average surface area of 55.20 m2/g which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g) and an average pore diameter of 8.36 nm. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation, which was 19.7% greater than using the same photo-catalyst under strict UV light irradiation. Photo-catalysis using these nanoparticles was observed to be very effective. The prepared novel visible light active nanocomposite has great potential for incorporation into water treatment systems because it exhibits good stability and magnetism as well as high photocatalytic efficiency.
关键词： methylene blue,titanium dioxide,water treatment,maghemite,photo-catalysis,magnetic nanocomposite
更新于2025-09-23 15:22:29
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Modification of graphene oxide with titanium dioxide by alcoholic reduction
摘要： Graphene oxide (GO) nanocomposites doped with DEGUSSA (P25) was synthetized by (GO) alcoholic reduction at high temperatures, during the reduction the P25 anchored to the spaces left by carbonyls groups in the graphene network, this incorporation improved photocatalytic behavior by retarding the electro-hole pair (e? hC). Raman spectroscopy con?rms the anchorage, because the material with higher load of TiO2 presented a band at 1100 cm?1 belonging to Carbonate’s groups (CO3) and a total modi?cation of the bands D and G, also this material presents a band gap of 2.54 eV. The P25 incorporation into graphene three-dimensional arrangement is notorious in diffraction x ray patterns, because the graphene diffraction pattern shows a sharpened and smaller peak than the starting graphene oxide. The incorporation of TiO2 to graphene sheets, improved the band gap, which P25 being of 3.2 eV was reduced to almost 2.5 eV, naturally this allows it, to be an excellent material to be used as photoanodes, photovoltaic devices and photocatalysis, its demonstrated by a photodegradation of methylene blue at 60 ppm exposed to solar light and 25 ppm exposed to a sodium lamp that emits radiation close to 589 nm.
关键词： methylene blue degradation,Band gap,graphene oxide,titanium dioxide
更新于2025-09-23 15:22:29
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Photocatalytic activity of anatase titanium dioxide nanostructures prepared by reactive magnetron sputtering technique
摘要： In this work, nanostructured titanium dioxide (TiO2) photocatalysts with high optical and structural homogeneity were successfully synthesized by dc reactive magnetron sputtering technique. The TiO2 thin films were produced with high structural homogeneity without any heat treatment. Analysis of the X-ray diffraction patterns and UV–visible spectroscopy gave an indication that the structure of prepared films is anatase with energy band gap of 3.23 eV. The Fourier-transform infrared spectroscopy has confirmed the formation of Ti–O bond. The average size of TiO2 particles in the deposited films was ranging in 5–7 nm. These nanostructures are very applicable as photocatalysts as their photocatalytic activity was determined from the degradation rate with UV irradiation time as the first order reaction rate constant was determined to be 2.4 × 10?3 min?1.
关键词： Anatase phase,Titanium dioxide,Nanostructures,Photocatalysis
更新于2025-09-23 15:22:29
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In-situ Platinum Plasmon Resonance Effect Prompt Titanium Dioxide Nanocube Photocatalytic Hydrogen Evolution
摘要： In-situ photodeposition Pt nanoparticles (Pt NPs) on TiO2 on account of the surface plasmonic resonance (SPR) effect and strong interaction of two components, which exhibits an elevated solar-driven photocatalytic hydrogen evolution performance. Herein, Pt-decorated TiO2 nanocube hierarchy structure (Pt-TNCB) was in-situ fabricated via a facile solvothermal synthesis and photodeposition strategy. The Pt-TNCB exhibits an excellent solar-driven photocatalytic hydrogen evolution rate (337.84 μmol h-1), which is about 37 times higher than that of TNCB (9.19 μmol h-1). Interestingly, its photocatalytic property is still superior to TNCB with post modification Pt (1 wt %) (208.11 μmol h-1). The introduction of Pt efficiently extends the photoresponse of composite material from UV to visible light region, simultaneously boost their solar-driven photocatalytic performance, which attribute to the porous structure, the subsize TNCB, the SPR effect of Pt NPs and strong interaction of two components. In fact, Pt NPs can enhance collective oscillations on delocalized electrons, which is conducive to capture electrons and hinder the recombination of photogenerated electron-hole pairs, leading to the longer lifetime of photogenerated charges. The fabrication of Pt-TNCB photocatalyst with SPR effect may provide a promising method to improve visible-light photocatalytic activities for traditional photocatalysts.
关键词： hydrogen evolution,titanium dioxide,surface plasmonic resonance,photodeposition,photocatalyst
更新于2025-09-23 15:22:29
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N-hydroxyphthalimide-TiO2 complex visible light photocatalysis
摘要： TiO2 is the most established semiconductor photocatalyst. The prominence of TiO2 is becoming increasingly obvious because its interfacial redox reactions have implication on a wide range processes such as energy conversion and environmental remediation. Herein, we exploited the surface complex created by the interaction between organic molecules with binding sites and accommodating surface of TiO2 for visible light-driven selective aerobic oxidation reactions. A novel surface complex formed between N-hydroxyphthalimide (NHPI) and TiO2 was discovered. The NHPI-TiO2 complex turned out to be an outstanding visible light photocatalyst and was successfully used in the selective oxidation of amines into imines with atmosphere O2 under blue LED irradiation. The stability of the NHPI-TiO2 complex was preserved by 3 mol% of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) acted as a cooperative catalyst. Moreover, selectivities for the imine products were also prompted by TEMPO. Superoxide radicals (O2?-) were evidenced to be the primary reactive oxygen species (ROS) to execute the oxidative conversions. This work suggests that TiO2 surface complexes can be robust photocatalysts for visible light-driven selective aerobic reactions, provided that an appropriate cooperative redox catalyst exists to channel the photocatalytic electron transfer.
关键词： titanium dioxide,surface complex,N-hydroxyphthalimide,molecular oxygen,TEMPO
更新于2025-09-23 15:22:29
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Chromium segregation in Cr-doped TiO2 (rutile): impact of oxygen activity
摘要： This work considers the effect of chromium surface segregation for polycrystalline Cr-doped TiO2 on surface vs. bulk defect disorder. It is shown that annealing of Cr-doped TiO2 (0.04 at% Cr) in the gas phase of variable oxygen activity at 1273 K results in a gradual transition in the valence of chromium at the surface from predominantly Cr3+ species in reduced conditions, p(O2) = 10?12 Pa, to comparable concentrations of both Cr3+ and Cr6+ species in oxidising conditions, p(O2) = 105 Pa. The reported data is considered in terms of defect equilibria leading to the formation of positively and negatively charged chromium in both the cation sub-lattice and interstitial sites. The derived theoretical models represent the effect of oxygen activity on the surface charge and the resulting electric field leading to migration mechanism of charged chromium species.
关键词： Oxygen activity,XPS,Cr-doped TiO2,Segregation,Titanium dioxide
更新于2025-09-23 15:22:29