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- 2019
- Dye-sensitized solar cell
- Photoelectrode
- Light scattering layer
- Transmittance
- White pigment (R902+)
- Rutile titanium dioxide
- Optoelectronic Information Materials and Devices
- Tribhuvan University
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A Photoresponsive Rutile TiO <sub/>2</sub> Heterojunction with Enhanced Electron-Hole Separation for High-Performance Hydrogen Evolution
摘要： Rutile titanium dioxide (TiO2) is a promising photocatalyst due to its high thermodynamic stability and few intragrain defects. However, it has not yet achieved photocatalytic activity comparable to that of anatase TiO2 owing to its higher recombination rate of electron–hole pairs. To effectively separate the electron–hole pairs in rutile TiO2, a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO2 nanosheets with different facets are coated in situ onto TiO2 nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO2, with an FH structure (FH-TiO2), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H2 production rate, respectively, are obtained compared to those of pure rutile TiO2 NRs. Moreover, FH-TiO2 delivers a 0.566 mmol g?1 h?1 H2 production rate even in pure water. This study offers important insights into the rational design of rutile TiO2 structures for highly efficient photocatalytic reactions.
关键词： charge separation,rutile TiO2,facet heterojunction,water splitting
更新于2025-09-23 15:22:29
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Hierarchical rutile/anatase TiO2 nanorod/nanoflower thin film: Synthesis and characterizations
摘要： Hierarchical TiO2 nanorod/nano?ower thin ?lm was synthesized on ?uorine doped tin oxide glass via hydrothermal and aqueous chemistry methods. According to ?eld emission scanning electron microscopy results, the thin ?lm was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 μm. They were perpendicular to the substrate owing to the TiO2 prenucleation. Growth of the nano?owers on the nanorods could increase both the speci?c surface area and roughness. X-ray di?raction and Raman spectroscopy showed that the nanorods were rutile; while the nano?owers were anatase. E?cient electron transfer from anatase to rutile could therefore occur. According to the di?use transmittance spectroscopy examination, the light harvesting rate was ameliorated and the band gap energy reduced to 2.83 eV. This was attributed to the F-doping the sample during synthesis. The enhancement of the photoelectrochemical activity allowed substitution of the TiO2 nanorod/nano?ower thin ?lm for the traditional TiO2 nanorods usually used in solar cells, sensors, and photocatalytic systems.
关键词： Aqueous chemistry,Nanorod array,Rutile/anatase TiO2,Hydrothermal,Nano?ower
更新于2025-09-23 15:22:29
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Crystalline topological Dirac semimetal phase in rutile structure
摘要： Based on first-principles calculations and symmetry analysis, we propose that a transition-metal rutile oxide, in particular β-PtO2, can host a three-dimensional topological Dirac semimetal phase. We find that β-PtO2 possesses an inner nodal chain structure when spin-orbit coupling is neglected. Incorporating spin-orbit coupling gaps the nodal chain while preserving a single pair of three-dimensional Dirac points protected by a screw rotation symmetry. These Dirac points are created by a band inversion of two d bands, which is a realization of a Dirac semimetal phase in a correlated electron system. Moreover, a mirror plane in the momentum space carries a nontrivial mirror Chern number nM = -2, which distinguishes β-PtO2 from the Dirac semimetals known so far, such as Na3Bi and Cd3As2. If we apply a perturbation that breaks the rotation symmetry and preserves the mirror symmetry, the Dirac points are gapped, and the system becomes a topological crystalline insulator.
关键词： PtO2,band inversion,symmetry analysis,rutile structure,topological Dirac semimetal,mirror Chern number
更新于2025-09-23 15:22:29
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Low-temperature-dependent growth of titanium dioxide nanorod arrays in an improved aqueous chemical growth method for photoelectrochemical ultraviolet sensing
摘要： The growth of titanium dioxide nanorod arrays (TNAs) in aqueous solutions containing titanium butoxide and hydrochloric acid can be controlled by regulating the temperature from 115 to 150 °C as an adjustable physical parameter. The transparent colloidal solution of titanates is clouded on the basic growth of TNAs when heated at a certain temperature using an improved aqueous chemical growth method in a clamped Schott bottle. The structural, optical and electrical properties of grown TNAs films were thoroughly investigated and discussed. The distinct and high-intensity peaks observed in the X-ray diffraction pattern and Raman spectra of the grown TNAs show the rutile phase with high crystal quality. The crystallite size, diameter size, and thickness of TNAs decrease with decreasing growth temperature. The prepared TNAs were used to detect 365 nm ultraviolet (UV) photon energy (750 μW/cm2) in a photoelectrochemical cell structure with a maximum photocurrent of 26.31 μA and minimum photocurrent of 3.48 μA recorded for TNAs grown at 150 °C and 115 °C, respectively. The size, structural properties, charge transfer resistance, and electron lifetime play a key role in determining the UV sensing characteristics of the TNAs. Results show that TNAs are very promising in fabricating a UV sensor with a high response at 0 V bias even at a low growth temperature of 115 °C.
关键词： Photoelectrochemical ultraviolet sensing,Titanium dioxide nanorod arrays,Rutile phase,Aqueous chemical growth method,UV sensor
更新于2025-09-23 15:21:21
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Ferromagnetic Properties of N-Doped and Undoped TiO2 Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide
摘要： In this work, undoped, N-doped, WO3-loaded undoped, and WO3-loaded with N-doped TiO2 rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO2 and WO3 loading onto TiO2 surface were used to increase and decrease oxygen vacancies. Various measurements were conducted to analyze the structural and magnetic properties of the samples. X-ray diffraction results showed that the N-doping and WO3 loading did not change the phase of all samples. X-ray photoelectron spectroscopy results revealed that W element loaded onto rutile single-crystal wafers existed in the form of WO3. UV-Vis spectrometer results showed that the absorption edge of WO3-loaded undoped and WO3-loaded with N-doped TiO2 rutile single-crystal wafers had red shift, resulting in a slight decrease in the corresponding band gap. Photoluminescence spectra indicated that oxygen vacancies existed in all samples due to the postannealing atmosphere, and oxygen vacancies density increased with N-doping, while decreasing with WO3 loading onto TiO2 surface. The magnetic properties of the samples were investigated, and the saturation magnetization values were in the order N-doped > WO3-loaded with N-doped > undoped > WO3-loaded undoped rutile single-crystal wafers, which was the same order as the oxygen vacancy densities of these samples. N-doping improved the saturation magnetization values, while WO3-loaded decreased the saturation magnetization values. This paper reveals that the magnetic properties of WO3-loaded with N-doped rutile single-crystal wafers originate from oxygen vacancies.
关键词： rutile TiO2 single-crystal wafers,WO3-loaded,oxygen vacancy,ferromagnetic properties
更新于2025-09-23 15:21:01
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White Painting Pigment as a Low-Cost Light Scattering Material for Bilayer Photoelectrodes of Dye-Sensitized Solar Cells
摘要： White pigment (DuPont R902+) has been used as a light scattering material in the preparation of bilayer photoelectrodes of dye-sensitized solar cells (DSCs). The X-ray diffraction (XRD) pattern of the white pigment revealed that the material consists of rutile phase of titanium dioxide. The light scattering layer prepared from the white pigment was coated onto the main-layer of the photoelectrodes of DSCs. The solar cells with and without light scattering layer were tested in the simulated light of 100 mW/cm2. The DSCs with the light scattering layer generated more current density than the DSCs without scattering layer and the overall light to electric power conversion efficiency of DSCs with the light scattering layer was ~4.00 % compared with 3.25 % efficiency of the DSCs without the scattering layer.
关键词： Dye-sensitized solar cell,Photoelectrode,Light scattering layer,Transmittance,White pigment (R902+),Rutile titanium dioxide
更新于2025-09-23 15:19:57
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Carbon quantum dots modified anatase/rutile TiO2 photoanode with dramatically enhanced photoelectrochemical performance
摘要： Titanium dioxide (TiO2) is a promising photoanode material for photoelectrochemical (PEC) water splitting, but the severe bulk recombination of photongenerated carriers, the sluggish oxygen evolution reaction (OER) kinetics and the poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on the rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and light harvesting were obtained. The bulk charge separation efficiency (ηbulk) and the surface charge injection efficiency (ηsurface) of CQDs/A/R-TiO2 are 1.69 and 5.74 times higher than that of the pristine TiO2 at 0.6 V vs. RHE, respectively. The photocurrent of CQDs/A/R-TiO2 is increased by 11.72 times and the onset potential of CQDs/A/R-TiO2 is negatively shifted by 240 mV.
关键词： Anatase/rutile TiO2 heterojunction,Carbon quantum dots,Bulk and surface charge transfer kinetics,PEC,Light harvesting
更新于2025-09-23 15:19:57
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Improved CdS QDSSCs with graphene and anatase-rutile TiO2 composite as photoanodes
摘要： In this paper, we developed a simple and convenient method for incorporating graphene with anatase-rutile TiO2 composite and applied it as photoanode to improve the photovoltaic performance of CdS QDSSCs. Our research indicated in a CdS QDSSC system, the photoelectric conversion efficiency (PCE) of anatase-rutile TiO2 (TGr0) composite photoanode was 86% higher than that rutile TiO2 NRs. We also found that the PCE increased first and then decreased with the change of graphene content after the graphene was introduced into the anatase-rutile TiO2 photoanode. When the ratio of optimized graphene/anatase TiO2 particles composite that spin-coated on rutile TiO2 NRs photoanode was 5%, we attained a maximum PCE of 2.20%, which was 178% and 50% higher than that pure TiO2 NRs (0.79%) and TGr0 (1.47%), respectively.
关键词： Anatase-rutile TiO2,CdS quantum dots,Graphene,Photovoltaic performance
更新于2025-09-23 15:19:57
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Effect of seed layer on growth of rutile TiO <sub/>2</sub> nanorods
摘要： For achieving the high quality of titanium dioxide (TiO2) nanorods, herein, we present a synthesis of rutile TiO2 nanorods on a transparent conductive fluorine-doped tin oxide (FTO) glass substratewith seed layer by a two-step method. TiO2 thin films were first precoated by spin coating and annealing, followed by the growth of TiO2 nanorods with a hydrothermal method. The crystallographic nanostructures and properties of the nanorods were investigated. XRD results demonstrate that seed layer was tetragonal anatase TiO2 structure while nanorods had tetragonal rutile TiO2 structure. Since the hydrothermal technique was conducted in medium acid, structure of nanorods was induced to form in rutile phase. The major characteristic orientation of nanorods on the seed layers was (002) and minor in (101) planes. FE-SEM results show that seed layer enhances the process to achieve vertical-aligned orientation of the TiO2 nanorods, which contribute to develop electron transport rate and could pay an important role inelectron transport layer in high-performance Perovskite solar cell.
关键词： seed layer,hydrothermal method,rutile TiO2 nanorods,Perovskite solar cell,electron transport layer
更新于2025-09-23 15:19:57
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Synthesis and photocatalytic properties of electrodeposited bismuth oxyiodide on rutile/anatase TiO<sub>2</sub> heterostructure
摘要： Bismuth oxyiodide (BiOI) modified rutile/anatase TiO2 heterostructure was fabricated by a three-step process. Anatase TiO2 sheet was first formed on fluorine-doped tin oxide (FTO) glass substrate. Rutile TiO2 nanorods were then grown on anatase TiO2 sheet via a hydrothermal process. BiOI was finally coated on the surface of hierarchical TiO2 film using an electrochemical deposition method. Photocatalytic tests on degradation of methylene blue (MB) in water indicated that BiOI modified hierarchical TiO2 film possessed an excellent photocatalytic activity superior to those of the monophase anatase and rutile TiO2 films, commercial P25 film and hierarchical TiO2 film. The enhanced photocatalytic performance was probably attributed to the synergetic effects of strong visible light absorption and formation of heterojunctions by the interfaces in the BiOI / rutile TiO2 / anatase TiO2 / FTO structure, which promoted efficient separation of photoinduced electron-hole pairs. In addition, the main active species during the degradation were confirmed to be hydroxyl radicals and superoxide radicals.
关键词： hierarchical rutile/anatase TiO2,nanostructure,film,electrodeposition,charge carrier separation,visible absorption,BiOI
更新于2025-09-19 17:15:36