Electrospinning preparation and dye adsorption capacity of TiO2@Carbon flexible fiber

TiO₂@carbon flexible fiber was prepared by combining electrostatic spinning technology and hydrothermal synthesis method. The XRD, SEM, TEM and Zeta potential techniques were used to characterize the phase, microstructure and surface charge properties of the samples. The growth mechanism of TiO₂ nanoarray on carbon flexible fiber with different morphologies was studied, and the dye adsorption capacity of the samples was evaluated by methylene blue (MB) degradation effect. The results showed that proper doping amounts of TiO₂ particles improved the flexibility and the hydrophilic property of carbon fiber significantly, which was conducive to the deposition and growth of TiO₂ on the carbon fiber. With the increase of hydrothermal time, the TiO₂ nanoarray grew denser gradually along the [110] crystal surface. The negative charge on the surface of carbon fiber increased, which was benefited to the removal of MB. The dye adsorption capacity of TiO₂@carbon fiber was resulted from the synergistic effect of physical adsorption (carbon fiber) and photocatalysis (TiO₂) process.     

Coumarin based sensitizers with ortho-halides substituted phenylene spacer for dye sensitized solar cells

The performance of DSSCs (dye sensitized solar cells) with a new series of dyes having different halide groups (i.e. F, Cl and Br) on o-position substituted phenyl spacers with same coumarin donor moieties have been reported. Optical, electrochemical, molecular orbital and photovoltaic properties were studied by varying the halide groups using these dyes. The replacement of halide atoms in same coumarin based dye had a significant effect on the short circuit current density (J_sc), open circuit voltage (V_oc), and photo conversion efficiency (PCE). The J_sc and PCE of dye CD-1 (fluorine substituted) are 10.3 mA/cm² and 5.2% respectively, which is higher than CD-2 (chlorine substituted) and CD-3 (bromine substituted) dyes (having PCE 4.1% and 3.5% respectively) devices. The optimized geometry calculation of o-halide phenyl π-spacer dyes were ascertained by density functional theory (DFT) using the B3LYP/6-31G(d,p) basis set. Moreover, we have checked the effect of various substituents in the same dye structure by DFT analysis.     

Charge Generation and Photovoltaic Operation of Solid‐State Dye‐Sensitized Solar Cells Incorporating a High Extinction Coefficient Indolene‐Based Sensitizer

An investigation of the function of an indolene‐based organic dye, termed D149, incorporated in to solid‐state dye‐sensitized solar cells using 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxypheny‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) as the hole transport material is reported. Solar cell performance characteristics are unprecedented under low light levels, with the solar cells delivering up to 70% incident photon‐to‐current efficiency (IPCE) and over 6% power conversion efficiency, as measured under simulated air mass (AM) 1.5 sun light at 1 and 10 mW cm^?2. However, a considerable nonlinearity in the photocurrent as intensities approach “full sun” conditions is observed and the devices deliver up to 4.2% power conversion efficiency under simulated sun light of 100 mW cm^?2. The influence of dye‐loading upon solar cell operation is investigated and the thin films are probed via photoinduced absorption (PIA) spectroscopy, time‐correlated single‐photon counting (TCSPC), and photoluminescence quantum efficiency (PLQE) measurements in order to deduce the cause for the non ideal solar cell performance. The data suggest that electron transfer from the photoexcited sensitizer into the TiO₂ is only between 10 to 50% efficient and that ionization of the photo excited dye via hole transfer directly to spiro‐OMeTAD dominates the charge generation process. A persistent dye bleaching signal is also observed, and assigned to a remarkably high density of electrons “trapped” within the dye phase, equivalent to 1.8 × 10¹⁷ cm^?3 under full sun illumination. it is believed that this localized space charge build‐up upon the sensitizer is responsible for the non‐linearity of photocurrent with intensity and nonoptimum solar cell performance under full sun conditions.     

Electro-Fenton decoloration of dyes in a continuous reactor: A promising technology in colored wastewater treatment

This study focuses on the application of Electro-Fenton technique for the remediation of wastewater contaminated with synthetic dyes. A bubble reactor was designed to develop this treatment operating in continuous mode. In order to increase the efficiency of Electro-Fenton treatment, the effect of key parameters (iron dosage and pH) that play an important role in this process was investigated for Lissamine Green B decoloration in batch mode. Operating at the optimal conditions, determined for Lissamine Green B, several dyes (Methyl Orange, Reactive Black 5 and Fuchsin Acid) were decolorized by using Electro-Fenton process. A first-order kinetic model was used to simulate the experimental results operating at different pH, and iron concentration of 150 mg L⁻¹. This kinetic model for Lissamine Green, Methyl Orange and Reactive Black 5 was successfully used in the progression of the process from batch to continuous mode. About 80% color removal was achieved for Lissamine Green and Methyl Orange with a residence time of 21 h. The decoloration for Reactive Black 5 was lower, reached a value around 60% at the same residence time. Nevertheless in all assays a good agreement between experimental results and proposed model in a continuous bubble reactor was detected. In addition a continuous treatment with a mixture of dyes was carried out. Operating with a residence time of 21 h the obtained decoloration was close to 43% which is squared with a TOC reduction around 46%. Therefore, the results provide fundamental knowledge for the treatment of a real wastewater stream.     

LCDs用彩色滤光片

本文介绍了ＬＣＤＳ用彩色滤光片（ＣＦ）的结构和特性，并较详细地讨论了当今几种流行的ＣＦ制造方法。     

CaCO3/TiO2 Nanoparticles Based Dye Sensitized Solar Cell

In this communication,the synthesis and structural,morphological,optical,and photo-electrochemical properties of TiO_2 and CaCO_3/TiO_2 nanoparticles as well as their applications in dye sensitized solar cells(DSSCs),have been reported.In an X-ray diffraction pattern of CaCO_3/TiO_2 nanoparticles,the peak at 29.41°of CaCO_3 has been detected,demonstrating its coating on the surface of TiO_2,which is further verified using high resolution-transmission electron microscopy,energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy.The strong quenching in photoluminescence emission,in the case of CaCO_3/TiO_2nanoparticles,has been attributed to the decrease in recombination rate of photo-generated electron—hole pairs.In the case of UV—visible reflectance spectra,the absorption edge for CaCO_3/TiO_2 nanoparticles has slightly been found to be blue-shifted as compared to bare TiO_2 nanoparticles,which corresponds to an increase in energy band gap of the former.The dye desorption studies reveal that CaCO_3/TiO_2 electrodes adsorbed more dye than the bare TiO_2 electrode.CaCO_3/TiO_2 based DSSC show improved photoelectrochemical properties compared to the bare TiO_2 based DSSC as CaCO_3 coating on TiO_2 forms an energy barrier,and,consequently suppressing the charge recombination,and,thus,improving the overall energy conversion efficiency(η) from 0.46%to 1.44%under the illumination of simulated light of 100 mW/cm~2.     

Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO₂ film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H₂SO₄/Eu(NO₃)₃ mixture solution.The specific surface area and the roughness of the anodic titania film fabricated in the H₂SO₄/Eu(NO₃)₃ electrolyte, were increased compared to that of the anodic TiO₂ film prepared in H₂SO₄ solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO₂ film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO₂ film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO₂ band gap by N and Eu co-doping.     

Dye sensitized solar cells based on zinc oxide bottle brush

In this work, we report on the synthesis of zinc oxide (ZnO) bottle brush; by a cost effective and low temperature aqueous chemical route on fluorine doped tin oxide (FTO) coated conducting glass substrates. This bottle brush-like morphology enables 43% improvement in solar energy conversion efficiency as compared to the aligned nanorods (NRs). This improvement has been attributed to the more dye loading and effective light scattering within the photoelectrode. The light scattering increases the interaction between photons and dye molecules, hence increases the absorption. Also, the vertical NRs provide the direct path for electron transport for collection. The optical spectra reveal that the bottle brush-like structure has higher absorption as compared with the NRs.     

Progress in light harvesting and charge injection of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) based on nanocrystalline semiconductors such as TiO₂ are of great interest as an alternative to the conventional solar cells because of their high performance, low-cost production, and environmental advantages. The DSSCs consist of dye molecule coated wide bandgap semiconductor layer, electrolyte, and transparent conducting oxide (TCO) film. When the DSSCs are exposed to solar light, an incident photon creates a bound electron-hole pair in dye sensitizers. Electrons then flow into the oxide nanoparticle anode due to a difference in the energy levels. On the other hand, holes move to the counter electrode through sequential redox reactions in the electrolyte. Therefore, the cell performance is influenced by parameters such as the morphology and optical properties of nanocrystalline oxide films, the electrochemical characteristics of redox electrolytes, and the photochemical properties of molecular sensitizers. In this article, we review the major components of DSSCs such as the oxide semiconductor film, sensitizing dyes, electrolytes, and TCO and discuss their progress to maximize light harvesting and charge injection efficacy. Their electrical, optical, and chemical properties are well correlated to optimize the light harvesting and charge injection of DSSCs. We have also shown recent efforts to improve the energy conversion efficiency, long term stability, sustainability and affordability by modifying or revolutionizing the components of DSSCs. This includes a prospect on the potential commercialization of DSSCs.