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Photocatalytic activity of gadolinium doped TiO <sub/>2</sub> particles for decreasing heavy metal chromium (VI) concentration
摘要： Titanium dioxide (TiO2) is among the most potential photocatalyst. However, TiO2 only works under UV light due to the relatively wide band gap energy. To overcome this, TiO2 is infiltrated (doped) by rare earth elements such as gadolinium (Gd). TiO2 was synthesized using sol gel method, while Gd/TiO2 photocatalyst was synthesized by the mixing methods of sol-gel and impregnation. The crystals are then characterized using XRD and SEM-EDX. The XRD diffractogram demonstrated that the crystallinity synthesized of TiO2 had an anatase structure similar to the structure of anatase P-25 as references. The SEM-EDX showed that Gd ion could not enter the crystal lattice, but only dispersed on the surface of TiO2 particles. The optimum result of decreased Cr(VI) concentration was reported using Gd/TiO2 1% w/w by a decrease of up to 94%, after irradiated with ultraviolet for one hour.
关键词： sol-gel method,gadolinium doping,TiO2,Cr(VI) concentration,photocatalyst
更新于2025-09-04 15:30:14
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Electrical characteristics of PbO–CaO–TiO2–SiO2–B2O3 glass ceramics doped with germanium
摘要： Various glass samples in the compound 55[(PbxCa1?x)O?TiO2]-44[2SiO2?B2O3]-1Ge (0 ≤ x ≤ 0.7) were fabricated by using the melt-quenching technique and their glass ceramics (GC) were obtained by controlled crystallization of the glass samples. The identification of phase and crystal structure with measurement of cell parameters was carried out using X-ray diffractometer (XRD). XRD results revealed the presence of the single phase formation of rutile (TiO2). The surface morphology of the synthesized GC samples was evaluated using a scanning electron microscope (SEM). The electrical behaviour of three selected GC samples with x = 0.0, 0.3 and 0.7 was being widely studied using impedance and immittance spectroscopy. The lead free GC sample, x = 0.0 possesses a high dielectric constant, 91,252 at low frequency (50 Hz) and high temperature (500 °C) due to space charge polarization that was ascertained by impedance spectroscopy of the tested samples. The fitting of impedance spectra with a modelled equivalent circuit was performed and different values of resistance and capacitance were calculated.
关键词： Dielectric constant,Rutile TiO2,Glass ceramics,Impedance spectroscopy,Space charge polarization
更新于2025-09-04 15:30:14
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Hole-induced polymerized interfacial film of polythiophene as co-sensitizer and back-electron injection barrier layer in dye-sensitized TiO2 nanotube array
摘要： In this work, we demonstrate that an ultra-thin film of polythiophene deposited interfacially via hole-induced polymerization on the surface of dye-sensitized TiO2 nanotube array acts as co-sensitizer, and hinders back-electron transfer in a DSSC. Consequently, the dark current, and the recombination reactions can be suppressed, leading to an improved number of electron density at the TiO2 array electrode. Thus, an enhanced photocurrent, and power conversion efficiency of the device is achieved. This logical concept is experimentally justified, and the device, after polythiophene interfacial treatment, demonstrates an enhanced power conversion efficiency by the factor of 39.19%.
关键词： Interfacial treatment,Back-electron injection barrier,Hole-induced polymerization,TiO2 nanotubes,Polythiophene co-sensitizer,DSSC
更新于2025-09-04 15:30:14
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Reversible Photodoping of TiO <sub/>2</sub> Nanoparticles for Photochromic Applications
摘要： Observations on the strong photochromic effect of crystalline TiO2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO2 nanoparticles (NPs) and are dispersed in butanol (8% by mass). Obtained NPs exhibit a dramatic photoresponse to UV light, enabling effective transmittance modulation in a broad wavelength range extending from the visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photoresponse is attributed to hole-scavenging by butanol, TiO2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. The observed optical effect is reversible, and the initial high transmittance state can be restored simply by exposing the NPs to air. The applied NP synthesis route is economic and can be easily scaled for applications such as smart window technologies.
关键词： UV light,TiO2 nanoparticles,localized surface plasmon resonances,transmittance modulation,photochromic
更新于2025-09-04 15:30:14
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1T-Phase Tungsten Chalcogenides (WS <sub/>2</sub> , WSe <sub/>2</sub> , WTe <sub/>2</sub> ) Decorated with TiO <sub/>2</sub> Nanoplatelets with Enhanced Electron Transfer Activity for Biosensing Applications
摘要： Layered transition metal dichalcogenides (TMDs) have received a great deal of attention due to fact that they have varied band gap, depending on their metal/chalcogen composition and on the crystal structure. Furthermore, these materials demonstrate great potential application in a myriad of electrochemical technologies. Heterogeneous electron transfer (HET) abilities of TMD materials toward redox-active molecules occupy a key role in their suitability for electrochemical devices. Herein, we introduce a promising biosensing strategy based on improved heterogeneous electron transfer rate of WS2, WSe2, and WTe2 nanosheets exfoliated using tert-butyllithium (t-BuLi) and n-butyllithium (n-BuLi) intercalators decorated with vertically aligned TiO2 nanoplatelets. By comparison of all the nanohybrids, decoration of TiO2 on t-BuLi WS2 (TiO2@t-BuLi WS2) results in the fastest HET rate of 5.39 × 10?3 cm s?1 toward ferri/ferrocyanide redox couple. In addition, the implications of decorating tungsten dichalcogenides (WX2) with TiO2 nanoplatelets in enzymatic biosensor applications for H2O2 detection are explored. TiO2@t-BuLi WS2 outperforms all other nanohybrid counterparts and is demonstrated to be an outstanding sensing platform in enzyme-based biosensor with wide linear range, low detection limit, and high selectivity. Such conceptually new electrocatalytic detection systems shall find the way to the next generation biosensors.
关键词： heterogeneous electron transfer,H2O2 detection,nanosheets,TiO2 nanoplatelets,transition metal dichalcogenides
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - A Study on the Atomic Topography of Nanostructured TiO<inf>2</inf>Thin Films: Effect of Annealing
摘要： Titanium dioxide (TiO2) is one of the most investigated metal oxides due to the wide range of applications such as photocatalysts. Photocatalytic activity will increased when the surface area is higher. Hence, this research focus on the surface topography and roughness of nanostructured TiO2 films characterized by atomic force microscopy (AFM) in order to obtain thin films with the optimum roughness for photocatalytic activity. TiO2 thin films were prepared by spin coating method at room temperature. The TiO2 solutions of 0.1 - 0.2 M were synthesized from titanium butoxide in ethanol. TiO2 films were deposited on the silicon substrates and annealed at 450°C. The results shown when the film was annealed, the grain were clearly observed. The grain size and the roughness increased when the film were annealed at high temperature. 0.2 M of TiO2 thin film exhibit the higher roughness with Ra and RMS values were 51.29 and 78.90 nm, respectively.
关键词： Molarity,Roughness,TiO2,Topography,AFM
更新于2025-09-04 15:30:14
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Improvement of the Degradation of Methyl Orange Using a TiO2/BDD Composite Electrode to Promote Electrochemical and Photoelectro-Oxidation Processes
摘要： Electrophoretic deposit of titanium dioxide (TiO2) was carried out over a boron doped diamond plate of 2 cm2, annealing at 350 °C to produce binary TiO2/BDD composite electrode. The composite was characterized by scanning electron microscopy (SEM) and linear sweep voltammetry (LSV) response. N,N-dimethyl-p-nitrosoaniline (RNO) was used as a probe molecule for the detection of free radicals (?OH) during the oxidation of water in phosphate buffer (pH 4) solution; at the TiO2/BDD/hv composite, an apparent first-rate kinetic constant of kobs = 0.1314 min-1 was observed. Afterwards, the composite electrode was applied to degrade 40 and 100 mg L-1 of a typical azo dye methyl orange (MO) via electrochemical process, such as: electro-oxidation (EO) and photoelectro-oxidation (PEO) under 25, 75 and 125 mA cm-2 current density (j); the PEO tests were performed using a UVA lamp at 365 nm. Results showed that the discoloration in the PEO process was larger than in the EO process, 96 and 100 %, respectively. Chemical Oxygen Demand (COD) was tested to evaluate the degradation. Hydroxylated derivatives were identified by means of mass spectroscopy during the PEO of MO in a TiO2/BDD/hv composite electrode.
关键词： TiO2/BDD composite,electrochemical process,hydroxyl radical formation,azo dye,water treatment
更新于2025-09-04 15:30:14
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Revisiting structural and photocatalytic properties of g-C3N4/TiO2: Is surface modification of TiO2 by calcination with urea an effective route to “solar” photocatalyst?
摘要： g-C3N4/TiO2 derived from the surface modification of TiO2 by calcination with urea has been widely studied as a “visible-light-active” photocatalyst for environmental purification applications. However, few attentions have been paid to the structure characterization and the photocatalytic properties of the resultant nanocomposite photocatalysts under a practical sunlight irradiation. Here we employ various characterization techniques, including TGA, XRD, TEM, XPS, UV-Vis spectrum, and N2-sorption analysis to characterize the evolutions in phase crystal structure, microstructure and optical properties of g-C3N4/TiO2 nanohybrids synthesized through calcining a mechanical mixture of urea and Evonik Aeroxide P-25 TiO2 (P25) at 350-500 oC. The thermal pyrolysis of urea leads to the surface decoration of TiO2 with graphitic carbon nitrate (g-C3N4) at temperatures above 400 oC. The photocatalytic properties of the resultant g-C3N4/TiO2 nanoparticles are evaluated through photocatalytic decoloration of methylene blue (MB) and reduction of Cr(VI) to Cr(III) under visible (420 nm), UV (365 nm), and simulated solar light irradiations. The nanohybrid photocatalysts, as most previous studies reported, show much higher photocatalytic activity under visible light irradiation than the single-component counterparts, i.e. P25 or g-C3N4. However, under solar and UV irradiation, no considerable improvements are found, which is caused by the decrease in redox potential upon interfacial charge carrier transfer between g-C3N4 and TiO2. Moreover, g-C3N4/TiO2 shows an ultralow photocatalytic activity in Cr(VI) reduction. The surface modification with organic g-C3N4 is assumed to tune the surface properties (e.g. hydrophilicity) of TiO2. Our results demonstrate that photocatalytic activity in UV range is as important as that in visible range, and developing efficient “solar” photocatalysts should balance both since they might be incompatible with each other.
关键词： graphitic carbon nitrate,dye degradation,TiO2 nanoparticles,Cr (VI) reduction,semiconductor photocatalysis,Aeroxide P25,charge carrier transfer
更新于2025-09-04 15:30:14
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Preparation and characterization of Pt, N-TiO2-graphene nanocomposites for hydrogen production
摘要： A hydrothermal technique was applied for the preparation of nitrogen-doped titania-reduced graphene oxide (NTRG) and platinum-nitrogen-codoped titania-reduced graphene oxide (PNTRG). Samples were characterized using various methods such as PL, UV–Vis, XRD, BET, TEM, and photocurrent testing. Production of hydrogen in the presence of visible light was selected to study the photocatalytic performance of TiO2 (T), N,TiO2 (NT), Pt, N-TiO2 (PNT), N-TiO2-rGO (NTRG) and Pt, N-TiO2-rGO (PNTRG) samples. The results reveal that the NTRG and PNTRG samples have high photocatalytic activity compared to the T, NT, and PNT samples. The photocatalytic performance of the PNTRG sample was greater than that of the T, NT, PNT and NTRG samples by 35, 3.5, 2.33 and 1.23 times, respectively. The results indicate that the increased photocatalytic activity was due to the hindered recombination rate of the photoinduced holes and electrons, an increase in the adsorption of reactants, and the shifting of the band gap energy from the ultraviolet region to the visible region. As a result, PNTRG is photocatalytically stable for five hydrogen production cycles.
关键词： N,TiO2,Hydrogen production,Pt,Graphene
更新于2025-09-04 15:30:14
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Ultra-small amorphous carbon dots: preparation, photoluminescence properties, and their application as TiO2 photosensitizers
摘要： Ultra-small carbon quantum dots (s-CQDs) with excitation wavelength-independent fluorescence had been obtained by hydrothermal-followed acid precipitation method and were characterized by FT-IR, TEM, XPS, UV–Vis and XRD. It was found that as-prepared s-CQDs were amorphous spherical particles with an average diameter of 1.51 nm, and there were abundant hydroxyl and carbonyl groups on their surfaces. Moreover, fluorescence emission study found that the luminescence of s-CQDs was aroused by oxygen group decorated on its surface, and the fluorescence properties of s-CQDs were much different from those of large CQDs (l-CQDs), which showed higher quantum yield and better photoluminescence (PL) property than that of l-CQDs. The PL of s-CQDs possessed two emission centers and was exhibited to be excitation independent. When s-CQDs was used as photosensitizer for TiO2 to photocatalytic degradation of methylene blue under visible light irradiation, it showed significantly improved photocatalytic activities compared with 1-CQDs, and the degradation efficiency of methylene blue reached up to 96.6%. The high degradation efficiency was attributed to the ultra-small particle size, abundant acidic groups, and excellent optical properties of s-CQDs.
关键词： Photocatalytic degradation,Ultra-small carbon quantum dots,TiO2 photosensitizers,Photoluminescence,Hydrothermal-followed acid precipitation method
更新于2025-09-04 15:30:14