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Size dependent radiation-stability of ZnO and TiO2 particles
摘要： ZnO and TiO2 particles are typical pigments used in solar reflective coatings. In this letter, the radiation stability of ZnO and TiO2 particles within submicron (several hundred nm) and nanoscale (30 nm) size is systematically studied. We reported previously that the 90 nm and 300 nm ZnO particles have nearly a same radiation tolerance (Phys. Status Solidi B 2017, 254, 1600411). Unexpectedly, we found herein that the 30 nm oxides have significant higher radiation tolerance in relation to the submicron particles. Detailed analysis illustrated that the abundant native defects and surface/interface states in oxides nanocrystals, in-situ restored radiation damage through rapid diffusion and annihilation with implantation created vacancies. This work would be beneficial for developing nanoscaled oxides and devices used for space and nuclear radiative environments.
关键词： radiation damage,optical properties,TiO2,ZnO
更新于2025-09-23 15:22:29
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Effects of substrate temperature and precursor amount on optical properties and microstructure of CVD deposited amorphous TiO2 thin films
摘要： In this research, TiO2 thin films were deposited on glass substrate by chemical vapor deposition using tetra isopropylorthotitanate as a precursor at low temperature. The TiO2 thin films were formed without using an oxygen source or annealing. Effects of substrate temperature and amount of the precursor on surface microstructure and optical properties of deposited TiO2 thin films were investigated. X-ray diffraction (XRD), UV-visible spectrophotometry and atomic force microscopy (AFM) were used to analyze the fabricated layers. The XRD analysis revealed that structure of all prepared layers was in amorphous phase. Analysis of AFM images showed that by increasing substrate temperature, the layer surfaces became rougher and simultaneously nanoparticle size was more uniform. Texture analysis revealed that increasing substrate temperature and decreasing precursor amount both increased surface isotropy. Thickness of layers was calculated by applying the Swanepoel method to the transmittance spectra. Variations in optical parameters were studied, including of optical band gap, refractive index, extinction coefficient, complex dielectric function, Urbach energy, single oscillator energy and dispersion energy. The results indicated that optical properties were functions of substrate temperature and precursor amount.
关键词： CVD,TiO2 thin film,Substrate temperature,Optical properties,Amorphous structure
更新于2025-09-23 15:22:29
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Characterization and removal of antibiotic residues by NFC-doped photocatalytic oxidation from domestic and industrial secondary treated wastewaters in Meric-Ergene Basin and reuse assessment for irrigation
摘要： Antibiotics are important contaminants that have become an increasingly big problem due to the discharge of the receiving environment. The presence of these organic based pollutants in influent wastewater can inhibit the biological processes and resist to degradation in wastewater treatment plants. Moreover, the consumption of agricultural products, irrigated with water containing antibiotic residues, leads to major harmful effects to the human body through the food chain. In this study; firstly, a conventional characterization was made in terms of COD, TOC, SS, color and of antibiotic residue characterization of untreated raw (influent) and biologically treated (effluent) water from domestic and industrial wastewater treatment plants located in the Meri?-Ergene Basin. After that, photocatalytic activity test was run under visible light for selected antibiotics (Erythromycin, Ciprofloxacin, Sulphametoxasol) which were detected by HPLC MS/MS in excess amount. Finally, for the photocatalytic oxidation, a new generation NFC (Nitrogen-Floride-Carbon)-doped titanium dioxide photocatalyst, which has never been studied in the literature before, was prepared according to the sol-gel method without using thermal processing. Photocatalysts were characterized by UV–vis DRS reflectance and Laser Raman Spectra measurements. All other analyzes were made according to the standard methods. Considering the conventional characterization results; investigated domestic wastewaters exhibited moderate characteristics while industrial wastewater samples had strong characteristics in terms of COD, TOC and SS pollution in accordance with the literature. By the way, contrary to expectations, antibiotic residue results have proved that the effluent wastewater contains more antibiotics than the influent. This can be explained by the fact that, some antibiotics in domestic wastewaters are probably already trapped in feces and cannot be purified by conventional systems since they are released after biological treatment, as mentioned similar studies in the literature. Moreover, by means of 7 h NFC-doped photocatalytic oxidation under visible light, beside approximately % 62 to %79 COD and 62%–86% TOC removal, %99 to %100 removal of antibiotic residue was provided. According to these results, domestic and industrial secondary treated wastewaters in Meric-Ergene Basin can be advance treated, succesfully, with NFC-doped photocatalyst to remove antibiotic residues besides conventional pollutants. This result show that Meri?-Ergene discharge criteria determined by Forest and Water Ministry of Turkey can be provided with this new type photocatalytic process and healthy reuse of this river for irrigation will be possible.
关键词： Advanced oxidation processes,Domestic/industrial wastewater,Solvent-casting method,UV,Antibiotic,Photocatalyst,NFC-doped TiO2
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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Contact Engineering for Dual-Gate MoS <sub/>2</sub> Transistors Using O <sub/>2</sub> Plasma Exposure
摘要： The benefits of O2 plasma exposure at the contact regions of dual-gate MoS2 transistors prior to metal deposition for high performance electron contacts is studied and evaluated. Comparisons between devices with and without the exposure demonstrate significant improvements due to the formation of a high-quality contact interface with low electron Schottky barrier (~0.1 eV). Topographical and interfacial characterization are used to study the contact formation on MoS2 from the initial exfoliated surface through the photolithography process and Ti deposition. Fermi level pinning near the conduction band is shown to take place after photoresist development leaves residue on the MoS2 surface. After O2 plasma exposure and subsequent Ti deposition, Ti scavenges oxygen from MoOx and forms TiOx. Electrical characterization results indicate that photoresist residue and other contaminants present after development can significantly impact electrical performance. Without O2 plasma exposure at the contacts, output characteristics of MoS2 FETs demonstrate non-linear, Schottky-like contact behavior compared to the linearity observed for contacts with exposure. O2 plasma allows for the removal of the residue present at the surface of MoS2 without the use of a high temperature anneal. A low conduction band offset and superior carrier injection are engineered by employing the reactive metal Ti as the contact to deliberately form TiO2. Dual-gate MoS2 transistors with O2 plasma exposure at the contacts demonstrate linear output characteristics, lower contact resistance (~20× reduction), and higher field effect mobility (~15× increase) compared to those without the treatment. In addition, these results indicate that device fabrication process induced effects cannot be ignored during the formation of contacts on MoS2 and other 2D materials.
关键词： TiO2,MoS2,contact resistance,O2 plasma,photoresist residue,MOSFETs,contacts
更新于2025-09-23 15:22:29
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Contact Angle Relaxation and Long-lasting Hydrophilicity of Sputtered Anatase TiO <sub/>2</sub> Thin Films by Novel Quantitative XPS Analysis
摘要： The contact angle relaxation of TiO2 surfaces is an important problem that must be understood, particularly for long-lasting hydrophilicity under dark conditions. The relaxation of sputtered anatase TiO2 thin films over a long time (~22 days) in an atmospheric environment was observed using quantitative XPS analysis. A new peak was identified as H2O within a donor-acceptor complex at ~2.57 eV above the lattice oxygen peak. This donor?acceptor complex turns out to be a key factor for long lasting hydrophilicity, and our model is presented. Adventitious carbon contamination was not the main cause of the contact angle relaxation. Instead, samples with lower amounts of donor?acceptor complexes (IDAC/Ibulk ≤ ~5%) underwent contact angle relaxation over time, and samples with a high density of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%) showed good hydrophilicity (contact angle ≤ 20°) over 22 days. Larger amounts of basic Ti?OH relative to acidic OHbridge (ITi?OH/Ibridge ≥ 1) resulted in greater amounts of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%). Thus, basic Ti?OH groups interact with H2O by forming a strong electrostatic donor?acceptor complex, leading to long-lasting hydrophilicity. Indeed, TiO2 was transformed to show long lasting hydrophilicity by high-density oxygen plasma treatment by forming sufficient Ti?OH groups and H2O molecules in the donor?acceptor complexes. Contact angle relaxation is closely related to the interactions between water molecules and the TiO2 surface in the dark. It is suggested that the relaxation depends on the number of electrostatic donor?acceptor complexes. This study provides new insight by linking theoretical studies with the experimental contact angle at the TiO2 surface in an ambient environment and is the first study that provides the presented relaxation mechanism.
关键词： Hydrophilicity,Sputtering,Plasma treatment,Contact angle relaxation,XPS analysis,Donor-acceptor complex,TiO2 thin films
更新于2025-09-23 15:22:29
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Growth orientation Mechanism of TiO<sub>2</sub> Nanotubes Fabricated by Anodization
摘要： TiO2 nanotube fabricated by anodization has been extensively researched in the past decades. However, the mechanism that controls the growth orientation of anodic TiO2 nanotube is still not clear. Here we firstly dig into their growth orientation systematically. Combining with previous literatures, the results of anodization on rotated Ti foil and thin Ti wire confirm that almost all of the TiO2 nanotubes grow vertically to the local Ti substrate surface. Their growth orientation predominantly depends on the local electric field around the nanotube bottom. The distribution of local electric field is regulated by the shape of initial nano-scale local Ti substrate surface. Mostly, the initial nano-scale local Ti substrate surface is nearly flat, which leaves vertical, circle and straight TiO2 nanotubes. In terms of evolution of TiO2 nanotubes fabricated on micron-scale convex surface, the vertical growth of TiO2 nanotubes leads to a continuous decrease in the oxide/substrate interface area, and a few TiO2 nanotubes are crushed and detached periodically from oxide/substrate interface. For micron-scale concave surface, due to the ever-increasing of oxide/substrate interface area, Y-branched TiO2 nanotubes occurred periodically as a response to avoid the vacancy on oxide/substrate interface.
关键词： growth orientation,anodic TiO2 nanotubes,concave surface,convex surface
更新于2025-09-23 15:22:29
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Enhanced generation of reactive oxygen species and photocatalytic activity by Pt-based metallic nanostructures: the composition matters
摘要： The modification of semiconductor nanostructures with metallic nanocomponents can promote the separation of electron/hole from photoexited semiconductors by forming heterojunctions, thus exhibit enhanced photocatalytic activities and potential applications. In this study, Pt-based NPs, including Pt, PtCu, and PtCuCo are employed as model co-catalysts to comparatively study their capability to enhance the photocatalytic activity of TiO2 nanosheets. It was found that each of Pt, PtCu, and PtCuCo can greatly enhance the photocatalytic activity of TiO2 toward degradation of organic dyes. Using electron spin resonance spectroscopy, we demonstrated that deposition of Pt-based NPs resulted in more production of reactive oxygen species including hydroxyl radicals, superoxide, and singlet oxygen. The enhancing effects of Pt-based NPs on generation of ROS and photocatalytic activity showed same trend: PtCuCo > PtCu > Pt. The mechanism underlying the enhancement differences in Pt-based NPs may be mainly related to electronic structure change of Pt in alloying with Cu and Co. These results are valuable for designing hybrid nanomaterials with high photocatalytic efficiency for applications in water purification and antibacterial products.
关键词： photocatalysis,hybrid nanostructures,reactive oxygen species,PtCuCo,TiO2
更新于2025-09-23 15:22:29
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Synthesis, characterization of TiO <sub/>2</sub> nano particles for enhancement of electron transport application in DSSC with Cu-BPCA Dye
摘要： Dye-sensitized solar cells [DSSCs] have attracted extensive attention due to their potential low cost and high energy efficiency, rendering them one of the most promising system for solar-to-energy conversion. The DSSC efficiency was enhanced by intermixing with the use of TiO2 nanoparticles which provides high surface area for accommodating the light-absorbing sensitizer and also the stable conductor for photo generated electrons. In hydrothermal method, the TiO2 nanoparticles synthesis depends on temperature. TiO2 nano particles diameter depends on different autoclaving temperature.TiO2 nanoparticles have been coated on ITO glasses by screen printing method. In this work, we have synthesized TiO2 nano particles which can provide a fast way for electron transport and reduced trapping of photo injected electrons during the path of back contact. The DSSCs were fabricated using the ruthenium dye and electrolyte (I3/I3-). The crystalline structure of TiO2 has been characterized by DLS, X-ray diffraction, SEM and TEM. The absorption spectra measured by using UV-Vis spectrometer. The IR spectrum has been recorded to know the peaks of Ti-O-Ti in powder sample. It has been found that the efficiency of DSSC was highly affected by the properties of nano particles.
关键词： Nanoparticles,Dye,DSSC,Titanium Dioxide (TiO2)
更新于2025-09-23 15:22:29
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Preparation of hollow yttrium-doped TiO<sub>2</sub> microspheres with enhanced visible-light photocatalytic activity
摘要： Using melamine-formaldehyde polymer microspheres as templates, yttrium-doped TiO2 hollow spheres (Y-TiO2HS) were successfully prepared via a sol-gel method. The as-synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectrum, luminescence spectrum, specific surface area (BET) analysis and porosity analysis. The results indicate that Y doping could increase the thermal stability, reduce the band gap and enhance photocatalytic activity of the TiO2. When the Y doping molar ratio was 1.5%, the Y-TiO2HS presented high surface area (62.651 m2 /g) and photocatalytic degradation rate (about 70%). The corresponding BET value and photocatalytic degradation rate of Y-TiO2HS increased by 3 times and 50%, respectively, compared with those of un-doped TiO2HS.
关键词： synthesis,yttrium doping,hollow microspheres,photocatalytic activity,TiO2
更新于2025-09-23 15:22:29