A new method for enhancing the charge separation and photo‐electrochemical stability of CuBi2O4 photoelectrodes by sequentially depositing Bi2O3 and CuO layers on fluorine‐doped tin oxide substrates with pulsed laser deposition (PLD), followed by rapid thermal processing (RTP), resulting in phase‐pure, highly crystalline films after 10 min at 650 °C, is reported. Conventional furnace annealing of similar films for 72 h at 500 °C do not result in phase‐pure CuBi2O4. The combined PLD and RTP approach allow excellent control of the Bi:Cu stoichiometry and results in photoelectrodes with superior electronic properties compared to photoelectrodes fabricated through spray pyrolysis. The low photocurrents of the CuBi2O4 photocathodes fabricated through PLD/RTP in this study are primarily attributed to their low specific surface area, lack of CuO impurities, and limited, slow charge transport in the undoped films. Bare (without protection layers) CuBi2O4 photoelectrodes made with PLD/RTP shows a photocurrent decrease of only 26% after 5 h, which represents the highest stability reported to date for this material. The PLD/RTP fabrication approach offers new possibilities of fabricating complex metal oxides photoelectrodes with a high degree of crystallinity and good electronic properties at higher temperatures than the thermal stability of glass‐based transparent conductive substrates would allow. 相似文献
The International Journal of Advanced Manufacturing Technology - The restoration of mandibular defects, especially large deformities is regarded as the most challenging surgical procedure owing to... 相似文献
Abstract: A stochastic simulation model of a project management game was developed to assist in training estimators in developing bidding strategies in construction. This paper discusses the development of the conceptual gaming model for bidding on construction projects and the implementation of the model on portable software. The model simulates the actual bidding in construction by creating projects, initiating random phenomena, and keeping track of the performance of the individual players of the game. Upon conclusion of the game the winner is selected as the player that maximizes his relative return on the original investment assigned to him by the game. The paper describes the underlying construction management concepts and the bidding process in general. The database management model is then detailed focusing on the requirements and strategy behind the development of the various databases. The paper also describes the various models utilized in simulating the involved random processes. Finally the operation of the program is introduced and its use in educating construction engineers and managers is highlighted. 相似文献
Recently, the application of metal oxides such as Fe3O4 nanoparticles have wide interest for environmental remediation and treatment of wastewater especially contaminated with azo dyes owing to its high degradation efficacy and low toxicity. The recovery of magnetic catalysts without losing their efficiency is an essential feature in the catalytic applications. The aim of this article is to investigate and synthesis of magnetically retrievable Fe3O4/polyvinylpyrrolidone/polystyrene (Fe3O4/PVP/PS) nanocomposite for the catalytic degradation of azo dye acid red 18 (AR18). Fe3O4/PVP/PS nanocomposite was prepared in two steps. Firstly, PVP/PS microsphere was synthesized by γ-irradiation polymerization of styrene in presence of PVP solution. Secondly, deposition of Fe3O4 nanoparticles on PVP/PS microsphere was achieved by the alkaline co-precipitation of Fe3+/Fe2+ ions. The chemical structural and morphological properties of PVP/PS microsphere and Fe3O4/PVP/PS nanocomposite were examined by XRD, TEM, DLS, FTIR, EDX and VSM techniques. TEM results showed homogeneous morphology, spherical shaped and well-dispersed Fe3O4 nanoparticles with average particle size of 26 nm around PVP/PS microspheres. The VSM measurements of Fe3O4/PVP/PS nanocomposite exhibit excellent magnetic response of saturation magnetization 26.38 emu/g which is suitable in magnetic separation. The effect of the synthesized Fe3O4/PVP/PS nanocomposite on the catalytic degradation of AR18 in presence of hydrogen peroxide (H2O2) as a heterogeneous Fenton-like catalyst was examined. The catalyst Fe3O4/PVP/PS/H2O2 played basic role in promoting the oxidation degradation efficiency of AR18 of initial concentration 50 mg/L to 94.4% in 45 min with excellent recyclability till the sixth cycles under the best conditions of pH 3, 2% v/v H2O2 and 0.3 g catalyst amount. Furthermore, the Fe3O4/PVP/PS/H2O2 hybrid catalyst system supports high capability for oxidation degradation of mixture of different dyes. The Fe3O4/PVP/PS nanocomposite catalyst had high magnetic and recyclability characters which are acceptable for the treatment of wastewater contaminated by various dyes pollutants.
Organosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H2O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m−2.h−1 with a selectivity of >10,000 for EA/H2O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H2O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n-propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost-effective, quick, and efficient synthesis route for practical membrane based applications. 相似文献
The correlation between structure and dielectric properties of lead-free (1-x)Na0.5Bi0.5TiO3 - xCaTiO3 ((1-x)NBT - xCT) polycrystalline ceramics was investigated systematically by X-ray diffraction, combined with impedance spectroscopy for dielectric characterizations. The system shows high miscibility in the entire composition range. A morphotropic phase boundary (MPB), at 0.09?≤?x?<?0.15 was identified where rhombohedral and orthorhombic symmetries coexist at room temperature. The fraction of orthorhombic phase increases gradually with x in the MPB region. Dielectric measurements reveal that the relative permittivity increase with addition of Ca2+. This behavior is unusual with this kind of doping. A thermal hysteresis occurred only in the MPB composition which varies in a non-monotonically manner with x, detected by dielectric properties. This phenomenon is related to the crystalline microstructure by a linear relationship between the fraction of each phase and dielectric properties, and, more precisely, to the strong interaction between rhombohedral and orthorhombic phases. 相似文献