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Photocatalytic performance of TiO2 thin film decorated with Cu2O nanoparticles by laser ablation
摘要： Cu2O nanoparticles decorated TiO2 thin films were fabricated by laser ablation. The effects of Cu2O nanoparticles on the structure, optical properties and photocatalytic performance of TiO2 thin film were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectrometer system, optical absorption and photocatalytic evaluation system, respectively. XRD patterns indicate that the decoration has the effect of lowering the grain orientation of Cu2O. The photocatalytic performance in hydrogen generation of Cu2O decorated TiO2 composite thin film was significantly improved compared with that of either Cu2O nanoparticles or TiO2 single layer thin film with 1.70 and 1.77 times, respectively. The oxidation of Cu2O was demonstrated to dominate the photocatalytic performances of Cu2O/TiO2 composite thin films by varying the laser ablation powers.
关键词： Heterojunction,Cu2O nanoparticles,Laser ablation,Photocatalytic performance,TiO2 thin film
更新于2025-10-22 19:40:53
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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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Enhancement of photocatalytic activity by femtosecond-laser induced periodic surface structures of Si
摘要： Laser induced periodic surface structures (LIPSS) represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography. This method is much simpler and cost effective. In this work, LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength. Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer. The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres. In first case, the oxygen pressure within the sputtering chamber was chosen to be high (3 × 10–2 mbar) whereas it was one order of magnitude lower in second case (2.1 × 10–3 mbar). In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films, respectively. The increase in photocatalytic activity is attributed to the enlargement of effective surface area. In comparative study, the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington ActivTM.
关键词： photocatalytic dye decomposition,silicon,femtosecond laser pulses,TiO2 thin film,laser induced periodic surface structures,nanoripples
更新于2025-09-23 15:19:57
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ZnO@TiO2 Core Shell Nanorod Arrays with Tailored Structural, Electrical, and Optical Properties for Photovoltaic Application
摘要： ZnO has prominent electron transport and optical properties, beneficial for photovoltaic application, but its surface is prone to the formation of defects. To overcome this problem, we deposited nanostructured TiO2 thin film on ZnO nanorods to form a stable shell. ZnO nanorods synthesized by wet-chemistry are single crystals. Three different procedures for deposition of TiO2 were applied. The influence of preparation methods and parameters on the structure, morphology, electrical and optical properties were studied. Nanostructured TiO2 shells show different morphologies dependent on deposition methods: (1) separated nanoparticles (by pulsed laser deposition (PLD) in Ar), (2) a layer with nonhomogeneous thickness (by PLD in vacuum or DC reactive magnetron sputtering), and (3) a homogenous thin layer along the nanorods (by chemical deposition). Based on the structural study, we chose the preparation parameters to obtain an anatase structure of the TiO2 shell. Impedance spectroscopy shows pure electron conductivity that was considerably better in all the ZnO@TiO2 than in bare ZnO nanorods or TiO2 layers. The best conductivity among the studied samples and the lowest activation energy was observed for the sample with a chemically deposited TiO2 shell. Higher transparency in the visible part of spectrum was achieved for the sample with a homogenous TiO2 layer along the nanorods, then in the samples with a layer of varying thickness.
关键词： TiO2 thin film,optical properties,ZnO nanorods,chemical deposition,DC reactive magnetron sputtering,pulsed laser deposition,electrical properties,core–shell
更新于2025-09-12 10:27:22