International Journal of Photoenergy

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Photocatalytic Decolourization of Direct Yellow 9 on Titanium and Zinc Oxides
International Journal of Photoenergy - Tập 2013 - Trang 1-9 - 2013
Elżbieta Regulska, Diana Małgorzata Bruś, Joanna Karpińska
The photodecolourization of Direct Yellow 9, a member of the group of azo dyes which are commonly used in the various branches of the industry, was investigated. The photostability of this dye was not previously examined. Photocatalytic degradation method was evaluated. Solar simulated light (E=500 W/m2), titanium dioxide, and zinc oxide were used as irradiation source and photocatalysts, respectively. Kinetic studies were performed on a basis of a spectrophotometric method. Degradation efficiency was assessed by applying high performance liquid chromatography. Disappearance of a dye from titanium dioxide and zinc oxide surfaces after degradation was confirmed by thermogravimetry and Raman microscopy. Direct Yellow 9 was found to undergo the photodegradation with approximately two times higher efficiency when zinc oxide was applied in comparison with titanium dioxide. A simple and promising way to apply the photocatalytic removal of Direct Yellow 9 in titanium dioxide and zinc oxide suspensions was presented.
Thin film solar cells on glass by transfer of monocrystalline Si films
International Journal of Photoenergy - Tập 1 Số 2 - Trang 89-93 - 1999
Ralf B. Bergmann, Titus J. Rinke, R. M. Hausner, M. Grauvogl, Michael Vetter, J.H. Werner
Thin film solar cells based on monocrystalline Si films are transferred to a glass superstrate. Chemical vapor deposition serves to epitaxially deposit Si on quasi‐monocrystalline Si films obtained from thermal crystallization of a double layer porous Si film on a Si wafer. A separation layer that forms during this crystallization process allows one to separate the epitaxial layer on top of the quasi‐monocrystalline film from the starting Si wafer. We presently achieve an independently confirmed solar cell conversion efficiency of 9:26%. Ray tracing studies in combination with electrical device simulation indicate an efficiency potential of around 17% using simple device processing and moderate assumptions on minority carrier lifetime and surface recombination.
Effect of Subgrains on the Performance of Mono-Like Crystalline Silicon Solar Cells
International Journal of Photoenergy - Tập 2013 - Trang 1-8 - 2013
Su Zhou, Chunlan Zhou, Wenjing Wang, Yehua Tang, Jingwei Chen, Baojun Yan, Yan Zhao
The application of Czochralski (Cz) monocrystalline silicon material in solar cells is limited by its high cost and serious light-induced degradation. The use of cast multicrystalline silicon is also hindered by its high dislocation densities and high surface reflectance after texturing. Mono-like crystalline silicon is a promising material because it has the advantages of both mono- and multicrystalline silicon. However, when mono-like wafers are made into cells, the efficiencies of a batch of wafers often fluctuate within a wide range of >1% (absolute). In this work, mono-like wafers are classified by a simple process and fabricated into laser doping selective emitter cells. The effect and mechanism of subgrains on the performance of mono-like crystalline silicon solar cells are studied. The results show that the efficiency of mono-like crystalline silicon solar cells significantly depends on material defects that appear as subgrains on an alkaline textured surface. These subgrains have an almost negligible effect on the optical performance, shunt resistance, and junction recombination but significantly affect the minority carrier diffusion length and quantum efficiency within a long wavelength range. Finally, an average efficiency of 18.2% is achieved on wafers with hardly any subgrain but with a small-grain band.
Photoelectrocatalytic Degradation of Organic Pollutants in Aqueous Solution Using a Pt‐TiO<sub>2</sub> Film
International Journal of Photoenergy - Tập 2009 Số 1 - 2009
Chun He, Mudar Abou Asi, Ya Xiong, Dong Shu, Xiangzhong Li
A series of Pt‐TiO2 films with nanocrystaline structure was prepared by a procedure of photodeposition and subsequent dip‐coating. The Pt‐TiO2 films were characterized by X‐ray diffraction, scanning electronic microscope, electrochemical characterization to examine the surface structure, chemical composition, and the photoelectrochemical properties. The photocatalytic activity of the Pt‐TiO2 films was evaluated in the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of formic acid in aqueous solution. Compared with a TiO2 film, the efficiency of formic acid degradation using the Pt‐TiO2 films was significantly higher in both the PC and PEC processes. The enhancement is attributed to the action of Pt deposits on the TiO2 surface, which play a key role by attracting conduction band photoelectrons. In the PEC process, the anodic bias externally applied on the illuminated Pt‐TiO2 films can further drive away the accumulated photoelectrons from the metal deposits and promote a process of interfacial charge transfer.
Enhanced Solar Photoelectrochemical Conversion Efficiency of ZnO:Cu Electrodes for Water-Splitting Application
International Journal of Photoenergy - Tập 2013 - Trang 1-9 - 2013
Rekha Dom, Lijin Rose Baby, Hyun Gyu Kim, Pramod H. Borse
n-typeZnO:Cu photoanodes were fabricated by simple spray pyrolysis deposition technique. Influence of low concentration (range ~10−4–10−1%) of Cu doping in hexagonal ZnO lattice on its photoelectrochemical performance has been investigated. The doped photoanodes displayed 7-time enhanced conversion efficiencies with respect to their undoped counterpart, as estimated from the photocurrents generated under simulated solar radiation. This is the highest enhancement in the solar conversion efficiency reported so far for the Cu-doped ZnO. This performance is attributed to the red shift in the band gap of the Cu-doped films and is in accordance with the incident-photon-current-conversion efficiency (IPCE) measurements. Electrochemical studies reveal ann-typenature of these photoanodes. Thus, the study indicates a high potential of doped ZnO films for solar energy applications, in purview of the development of simple nanostructuring methodologies.
Preparation and Photocatalytic Property of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>TiO</mml:mtext></mml:mrow><mml:mn mathvariant="bold">2</mml:mn></mml:msub></mml:mrow></mml:math>/Diatomite-Based Porous Ceramics Composite Materials
International Journal of Photoenergy - Tập 2012 - Trang 1-4 - 2012
Shuilin Zheng, Chunhua Bai, Ruqin Gao
The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor ofTiO2and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at550°C,TiO2thin film loaded on the diatomite-based porous ceramics is anataseTiO2and average grain size ofTiO2is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.
In‐situ investigations of the photoluminescence properties of SiO<sub>2</sub>/TiO<sub>2</sub> binary and Boron‐SiO<sub>2</sub>/TiO<sub>2</sub> ternary oxides prepared by the sol‐gel method and their photocatalytic reactivity for the oxidative decomposition of trichloroethylene
International Journal of Photoenergy - Tập 5 Số 1 - Trang 31-36 - 2003
Kyeong Youl Jung, Seung Bin Park, Masaya Matsuoka, Masakazu Anpo
Photoluminescence behavior of TiO2, SiO2/TiO2 binary and Boron‐SiO2/TiO2 ternary oxides prepared by the sol‐gel method was investigated. The differences in their photocatalytic reactivities of TiO2‐based photocatalysts were interpreted in terms of the relationship of the difference in their photoluminescence characteristics. The addition of SiO2 into TiO2 matrix induced new photoluminescence sites, which were due to anchored titanium oxide species (i.e., the formation of Ti–O–Si bonds) located on the surface. The photoluminescence was found to be very sensitive to the presence of oxygen. These new photoluminescence completely disappeared by the addition of boron into SiO2/TiO2 binary oxide, since the emitting sites having a Ti–O–Si bond were destroyed and the new sites having B–O–Ti or Si–O–B bonds were constructed on the surface, being in agreement with the results obtained by FT‐IR measurements. For all TiO2‐based photocatalysts, a significant quenching of photoluminescence was observed by the addition of oxygen. It was found that the photocatalytic reactivity of TiO2‐based photocatalysts for the decomposition of trichloroethylene was clearly associated with their relative quenching efficiencies of photoluminescence; photocatalyst showing high quenching efficiency exhibited a high photocatalytic reactivity.
Hydrothermal Synthesis of Iodine-Doped Nanoplates with Enhanced Visible and Ultraviolet-Induced Photocatalytic Activities
International Journal of Photoenergy - Tập 2012 - Trang 1-12 - 2012
Jiang Zhang, Zheng‐Hong Huang, Yong Xu, Feiyu Kang
The iodine-doped Bi2WO6(I-BWO) photocatalyst was prepared via a hydrothermal method using potassium iodide as the source of iodine. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of I-BWO for the degradation of rhodamine B (RhB) was higher than that of pure BWO and I2-BWO regardless of visible light (>420 nm) or ultraviolet light (<400 nm) irradiation. The results of DRS analysis showed that the I-BWO and I2-BWO catalysts had narrower band gaps. XPS analysis proved that the multivalent iodine species including I0and were coadsorbed on the defect surface of Bi2WO6in I-BWO. The enhanced PL intensity revealed that a large number of defects of oxygen vacancies were formed by the doping of iodine. The enhanced photocatalytic activity of I-BWO for degradation of RhB was caused by the synergetic effect of a small crystalline size, a narrow band gap, and plenty of oxygen vacancies.
Highly Selective Deethylation of Rhodamine B on Prepared in Supercritical Fluids
International Journal of Photoenergy - Tập 2012 - Trang 1-7 - 2012
Yuzun Fan, Guoping Chen, Dongmei Li, Yanhong Luo, Nina Lock, Anca Paduraru Jensen, Aref Mamakhel, Jianli Mi, Steen B. Iversen, Qingbo Meng, Bo B. Iversen
Pure phase anatase TiO2nanoparticles with sizes of 5–8 nm and varying crystallinity were synthesized in supercritical isopropanol/water using a continuous flow reactor. Their photodegradation of rhodamine B (RhB) was evaluated under visible light irradiation. The as-prepared TiO2nanoparticles show much higher photodegradation efficiencies than commercial Degussa P25 TiO2. Moreover, the photodegradation of RhB on the as-prepared TiO2follows a different process from that on P25 TiO2, quicker N-deethylation and slower cleavage of conjugated chromophore structure. Based on PXRD, TEM, and BET measurements, these two photodegradation properties have been explained by the physicochemical properties of TiO2.
Photoinduced Synthesis of Hierarchical Flower-Like Ag/Bi<sub>2</sub>WO<sub>6</sub> Microspheres as an Efficient Visible Light Photocatalyst
International Journal of Photoenergy - Tập 2018 - Trang 1-8 - 2018
S. WU, Nianyuan Tan, Donghui Lan, Bing Yi
A series of three-dimensional microflower-like Ag/Bi2WO6 composites were synthesized through a simple and practical photoreduction process with different photoreduction times. The UV-visible diffuse reflectance spectra indicate that the spectrum of Ag/Bi2WO6 is significantly red-shifted compared to pure Bi2WO6 microspheres in the visible light region. The photocatalytic activities of the as-prepared samples were evaluated by the decolorization of rhodamine B under visible light irradiation. The photocatalytic reaction rate constants of the Ag/Bi2WO6 with a photoreduction time of 20 min was 3.60 times bigger than those of pure Bi2WO6. The enhanced photocatalytic activity could be attributed to the synergistic effect of increased light absorption range and the effective separation of photogenerated carriers caused by Ag nanoparticles.
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