共查询到20条相似文献,搜索用时 15 毫秒
1.
Shoichiro Yano Tatsuro Ito Kenichi Shinoda Hiroki Ikake Toshiki Hagiwara Takashi Sawaguchi Kimio Kurita Manabu Seno 《Polymer International》2005,54(2):354-361
Epoxy resin/TiO2 and epoxy resin/SiO2 hybrids were prepared by different procedures, and their mechanical properties were correlated to their microstructures, as indicated by small‐angle X‐ray scattering (SAXS) measurements. Epoxy resin/TiO2 hybrids were prepared by mixing the epoxy resin (EP828) with N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (S320) in acetone, and then titanium‐n‐butoxide (TnBU) was added. In addition, epoxy/SiO2 hybrids were prepared by mixing EP828 with a curing agent, a diamino heterocyclic compound (B002) in acetone, and an organo silica sol (silica nanoparticles dispersed in methylethylketone) was added. In the EP828/S320/TiO2 hybrid systems, the TiO2 component was attached to both of the chain ends of the epoxy matrix, hence leading to the formation of inorganic domains via the covalent bonds. SAXS profiles of these hybrids showed peaks at q = 2.3 nm?1, caused by interference between the domains. The storage modulus increased with increasing TiO2 content above the Tg, owing to the strong interactions between TiO2 and the epoxy matrix. The tanδ peak position did not change, although the intensity decreased with increasing TiO2 content. The SAXS profiles of the EP828/B002/SiO2 hybrids were very different to those of the corresponding EP828/S320/TiO2 hybrids, and indicated that SiO2 particles with rough surfaces were randomly dispersed in the epoxy matrix. The storage moduli of the EP828/B002/SiO2 hybrid systems increased only slightly with SiO2 content, because of the weak interactions. These mechanical properties are well explained by the microstructures derived from the SAXS profiles. Copyright © 2004 Society of Chemical Industry 相似文献
2.
Engineered TiO2 and SiO2‐TiO2 films on silica‐coated glass for increased thin film durability under abrasive conditions
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rosa Elena Ramírez‐García Jesús Alberto González‐Rodríguez Miguel Arroyo‐Ortega Sergio Alfonso Pérez‐García Liliana Licea‐Jiménez 《International Journal of Applied Ceramic Technology》2017,14(1):39-49
Thin films durability is critical to retain its performance in real life applications. For automotive glass, further factors such as haze appearance developed under abrasive conditions become relevant to ensure the driver's visibility. Macroscopic abrasion resistance tests of TiO2/SiO2 and SiO2–TiO2/SiO2 thin films on soda‐lime silica (SLS) glass were performed according to an American standard for safety grazing. The purpose of this, was to increase the top active film durability in a bilayer system by understanding how film thickness and top film composition influence abrasion performance. In order to achieve this understanding, three approaches were considered: (a) determination of the influence of TiO2 top film thickness, (b) replacement of the TiO2 top film by SiO2–TiO2 films, and (c) determination of the influence of SiO2–TiO2 film thickness. Results showed that thinner top TiO2 film thickness leads to SiO2/TiO2 bilayers with lower haze value and improved abrasion resistance. It was also found that SiO2 addition to TiO2 top film composition promotes the thin film adhesion and sample durability against abrasive wear. Friction coefficient and micro‐hardness measurements support the abrasion results. Factors contributing to the improvement of the lifetime performance of TiO2 and SiO2–TiO2 thin films were identified. 相似文献
3.
N‐Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra‐n‐butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first‐principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N‐doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N‐doped samples in the visible region. 相似文献
4.
Xiang Yuan Jianwei Zheng Qian Zhang Shuirong Li Yanhui Yang Jinlong Gong 《American Institute of Chemical Engineers》2014,60(9):3300-3311
The synthesis, characterization, and application of silica‐supported Cu‐Au bimetallic catalysts in selective hydrogenation of cinnamaldehyde are described. The results showed that Cu‐Au/SiO2 bimetallic catalysts were superior to monometallic Cu/SiO2 and Au/SiO2 catalysts under identical conditions. Adding a small amount of gold (6Cu‐1.4Au/SiO2 catalyst) afforded eightfold higher catalytic reaction rate compared to Cu/SiO2 along with the high selectivity (53%, at 55% of conversion) toward cinnamyl alcohol. Characterization techniques such as x‐ray diffraction, H2 temperature‐programmed reduction, ultraviolet‐visible spectroscopy, transmission electron microscopy, Fourier‐transform infrared spectra of chemisorbed CO, and x‐ray photoelectron spectroscopy were employed to understand the origin of the catalytic activity. A key genesis of the high activity of the Cu‐Au/SiO2 catalyst was ascribed to the synergistic effect of Cu and Au species: the Au sites were responsible for the dissociative activation of H2 molecules, and Cu0 and Cu+ sites contributed to the adsorption‐activation of C?C and C?O bond, respectively. A combined tuning of particle dispersion and its surface electronic structure was shown as a consequence of the formation of Au‐Cu alloy nanoparticles, which led to the significantly enhanced synergy. A plausible reaction pathway was proposed based on our results and the literature. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3300–3311, 2014 相似文献
5.
Shouxin Liu Xiaoyun Chen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(5):453-459
A photocatalyst, TiO2?xNy/AC (activated carbon (AC) supported N‐doped TiO2), highly active in both the Vis and UV range, was prepared by calcination of the TiO2 precursor prepared by acid‐catalyzed hydrolysis in an ammonia atmosphere. The powders were characterized by diffuse reflectance spectroscopy, scanning electron microscopy, X‐ray diffraction, N2 adsorption, Fourier transform infrared spectroscopy and phenol degradation. The doped N in the TiO2 crystal lattice creates an electron‐occupied intra‐band gap allowing electron‐hole pair generation under Vis irradiation (500–560 nm). The TiO2?xNy/AC exhibited high levels of activity and the same activity trends for phenol degradation under both Vis and UV irradiation: TiO2?xNy/AC calcined at 500 °C for 4 h exhibited the highest activity. The band‐gap level newly formed by doped N can act as a center for the photo‐generated holes and is beneficial for the UV activity enhancement. The performance of the prepared TiO2?xNy/AC photocatalyst revealed its practical potential in the field of solar photocatalytic degradation of aqueous contaminants. Copyright © 2007 Society of Chemical Industry 相似文献
6.
Polyaniline/nano‐titanium dioxide composites (PANI/n‐TiO2) were prepared using α‐dextrose as surfactant and ammonium per sulfate as oxidant. The PANI/n‐TiO2 composite is characterized by Fourier transform infrared spectra and confirmed the presence of benzenoid and qunoide ring structures and also formation of free ions. The transmission electron microscopy study reveals that the size of TiO2 is in the order of 7 nm where as the composite size is of the order of 13 nm; further, it is observed that the TiO2 particles are intercalated to form a core shell of PANI. The X‐ray diffraction (XRD) studies show that the monoclinic structure of the composites. ac Conductivity, permittivity, and tangent loss studies on these samples suggest that these composites may be well suited for gas sensor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
7.
Sheng‐Li Chen Ai‐Jun Wang Chun‐Tian Hu Chao Dai Jay B. Benziger 《American Institute of Chemical Engineers》2012,58(2):568-572
An nc‐TiO2/SnO2 inverse opal composite membrane was fabricated, the photo‐activity of which was significantly enhanced by utilizing both slow photons and stop‐band reflection of the photonic crystal layer. The materials of the photonic crystal layer must be transparent in the area of adsorption edge of the nc‐TiO2, so that SnO2, having much greater electronic band gap than TiO2, was used for the materials of the photonic crystal layer. The photonic band‐gap of the SnO2 photonic crystal was designed at the semiconductor band gap of TiO2 to harvest slow photons in the interface between the SnO2 layer and the TiO2 layer. The two layer structure makes it possible to couple the stop‐band reflectivity of the photonic layer to the photocatalyst. Composite membranes can improve solar energy harvesting and substantially improve photocatalysts for photolysis and photochemical degradation of environmental pollutants. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
8.
Enzan Chen Haijia Su Tianwei Tan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(3):421-427
BACKGROUND: On the basis of effective bioaffinity adsorption of Ag+, silver nanoparticles (Ag NPs) were synthesized on the surface of chitosan‐TiO2 adsorbent (CTA) by TiO2 photocatalysis for crystal growth. RESULTS: Among the microstructure characterizations of the resulting silver nanoparticles‐ loaded chitosan‐TiO2 adsorbent (Ag‐CTA), X‐ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X‐ray (EDX) revealed the formation of metallic Ag on the CTA, which was further confirmed by the surface plasmon resonance of Ag NPs in the UV‐visible absorption spectrum. The underlying mechanism behind the formation of Ag NPs on the CTA by TiO2 photoreduction was studied by Fourier transform infrared (FTIR) spectroscopy. The distinctive feature of Ag‐CTA after adsorption was the highly efficient antimicrobial activity in inactivating different test strains. In the case of Escherichia coli, 1.50 mg 1.67 wt% Ag‐CTA could totally inhibit 1.0–1.2 × 107 colony forming units (CFU) in 100 mL nutrient medium, which was superior to that previously reported. CONCLUSIONS: CTA effectively adsorbed the precious metal ion Ag+ onto active imprinting sites on the adsorbent and then exerted efficient antimicrobial effects against diverse microbes. This research will be useful for designing a novel CTA‐based wastewater treatment for multi‐functional performance. Copyright © 2010 Society of Chemical Industry 相似文献
9.
The nano‐ZnO and nano‐TiO2 were added into chitosan (CS) anion layer to prepare polyvinyl alcohol (PVA) ‐ sodium alginate (SA)/ TiO2‐ZnO‐CS (here, PVA:polyvinyl alcohol; SA:sodium alginate) bipolar membrane (BPM), which was characterized using scanning electron microscopy, atomic force microscopy (AFM), thermogravimetric analysis (TG), electric universal testing machine, contact angle measurer, and so on. Experimental results showed that nano‐TiO2‐ZnO exhibited better photocatalytic property for water splitting at the interlayer of BPM than nano‐TiO2 or nano‐ZnO. The membrane impedance and voltage drop (IR drop) of the BPM were obviously decreased under the irradiation of high‐pressure mercury lamps. At a current density of 60 mA/cm2, the cell voltage of PVA‐SA/TiO2‐ZnO‐CS BPM‐equipped cell decreased by 1.0 V. And the cell voltages of PVA‐SA/TiO2‐CS BPM‐equipped cell and PVA‐SA/ZnO‐CS BPM‐equipped cell were only reduced by 0.7 and 0.6 V, respectively. Furthermore, the hydrophilicity, thermal stability, and mechanical properties of the modified BPM were increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
10.
Hongxia Guo Shaocheng Yu Tongtong Liu Quan‐Fu An Xiaoyan Ren Zhenping Qin Yucang Liang 《大分子材料与工程》2019,304(12)
The manipulation of surface wettability has been regarded as an efficient strategy to improve the membrane performances. Herein, the counterion‐switched reversibly hydrophilic and hydrophobic surface of TiO2‐loaded polyelectrolyte membrane are prepared by layer‐by‐layer assembly of poly(sodium 4‐styrene sulfonate) (PSS) and poly(diallydimethyl‐ammoniumchloride (PDDA) containing TiO2@PDDA nanoparticles (NPs) on the hydrolyzed polyacrylonitrile (PAN) substrate membrane. The obtained polyelectrolyte multilayer (PEM) membranes [PEM‐TiO2]4.5+X? (X? = Cl?, PFO? [perfluorooctanoate] etc.) show different hydrophilicity and hydrophobicity with various counterions. The integration of TiO2 NPs obviously improves the wettability and nanofiltration (NF) performance of PEM membrane for (non)aqueous system of dyes (crystal violet, eriochrome black T) with a high recyclability. The highly hydrophilic [PEM‐TiO2]4.5+Cl? (water contact angle [WCA]: 13.2 ± 1.8°) and hydrophobic [PEM‐TiO2]4.5+PFO? (WCA: 115.4 ± 2.3°) can be reversibly switched via counterion exchange between Cl? and PFO?, verifying the surface with a reversible hydrophilic–hydrophobic transformation. For such membranes, the morphology, wettability, and NF performance rely on the loading of TiO2@PDDA NPs and surface counterion. Meanwhile, the motion and interaction of water or ethanol in the hydrophilic or hydrophobic membrane are revealed by low‐field nuclear magnetic resonance. This work provides a facile and rapid approach to fabricate smart and tunable wetting surface for potential utilization in (non)aqueous NF separation. 相似文献
11.
Conducting polyaniline (PANI)/titanium dioxide (TiO2) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO2 particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO2 composite nanofibres was also discussed. This composite contained ~ 65% conducting PANI by mass, with a conductivity of 1.42 S cm?1 at 25°C, and the conductivity of control PANI was 2.4 S cm?1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
12.
A novel Nano/submicrofiber catalyst was prepared via electrospinning technology from poly (vinyl pyrrolidone) (PVP) and nano‐TiO2. First, nano‐TiO2 particles were added into the mixture of ethanol and deionized water, the mass ratio of ethanol and deionized water was 1 : 1, the TiO2 suspension was obtained after 1 h with ultrasonic treatment and centrifugal effect, Then PVP was added into the above‐mentioned suspension and the content of PVP in the sol was 28%. The TiO2/PVP solution was electrospun with different voltage. The effects of the content of TiO2 and electrospinning voltage on diameter of nano/submicrofiber were studied. The nano/submicrofiber catalyst was characterized by scanning electron microscopy, transmission electron microcopy, X‐ray diffraction, and Fourier transform infrared. The results show that the diameter of nano/submicrofiber increases with an increase of the content of nano‐TiO2 and decreases with the increase of electrospinning voltage. The analytical result showed that the nano‐TiO2 particles were well dispersed in the matrix of PVP, moreover, the crystal type of nano‐TiO2 was a mixture of anatase and rutile and the diameter of nano‐TiO2 particles in the nano/submicrofiber is in the range of 20–60 nm and the nano‐TiO2 particle was monodisperse, and the nano‐TiO2 particle and PVP molecule was connected by a hydrogen bonding. This nano/submicrofiber catalyst has a high efficiency on degradation on CH2O. 56.8 percent of CH2O was degraded under ultraviolet radiation in 80 min when the content of nano‐TiO2 is 20% in nano/submicrofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
13.
Te‐Li Su Yu‐Lin Kuo Tsai‐Jung Wu Fu‐Chen Kung 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(1):160-164
BACKGROUND: The aim of this study was to investigate improvement of the photocatalytic activity of visible‐light driven nitrogen‐modified TiO2 (N‐TiO2) powder toward methyl blue (MB) and direct blue‐86 (DB‐86) dyes. The Taguchi method with an L9 orthogonal array was applied to plan the synthesis parameters, i.e. nitrogen sources, nitrogen source concentrations, stirring time and calcined temperatures. 95% confirmation experiments were undertaken to verify the effectiveness of the Taguchi method. RESULTS: All N‐TiO2 photocatalysts were shifted toward the visible light region with the optical band gap (Eg). Nitrogen source concentrations were significant parameters for the photocatalytic decolorization rate constants (k values). In comparison with pure TiO2, the photodecolorization behavior of N‐TiO2 toward DB‐86 was superior with a reaction rate constant of 1.68 × 10?3 min?1, and a 4 h photodecolorization efficiency of 34%. CONCLUSION: The Taguchi method was reported to alter the surface properties of commercial Degussa P25 TiO2, which could then be used as a visible‐light driven photocatalyst. The visible‐light‐driven photocatalyst was investigated to determine material characteristics. Greater photodecolorization of MB and DB‐86 dye pollutants using optimally‐prepared N‐TiO2 under visible light irradiation was successfully obtained. Copyright © 2011 Society of Chemical Industry 相似文献
14.
Jun Wang Na Ding Zhaohong Zhang Shixian Wang Ying Guo Bin Liu Yuanyuan Zhang Xiangdong Zhang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(4):538-546
BACKGROUND: In order to effectively damage some biomolecules under ultrasonic irradiation, a mixed TiO2/SiO2 powder with high catalytic activity and selectivity was used as a sonocatalyst. RESULTS: The mixed TiO2/SiO2 powder heat treated at 450 °C for 30 min was adopted as a sonocatalyst and the damage to BSA molecules under ultrasonic irradiation was assessed. In addition, the effects of such variables as molar ratio of TiO2 and SiO2, treatment temperature and time, ultrasonic irradiation time, catalyst amount, solution acidity, ionic nature and strength, ultrasonic irradiation power and D2O concentration on the damage to BSA molecules were studied by means of UV‐visible and fluorescence spectra. The results showed that the degree of damage was aggravated by an increase in ultrasonic irradiation time, catalyst amount, solution acidity, ultrasonic irradiation power and D2O concentration, but was reduced by an increase in ionic strength. CONCLUSION: The results indicated that the mixed TiO2/SiO2 powder displayed higher activity and selectivity compared with nano‐sized TiO2 and SiO2 powders during the sonocatalytic damage of BSA. The extent of the damage decreased in the order TiO2/SiO2 > nano‐sized TiO2 > nano‐sized SiO2. These results are of great significance for applying sonocatalytic methods to treat tumours. Copyright © 2008 Society of Chemical Industry 相似文献
15.
Fang Li Yanji Wang Wei Xue Xinqiang Zhao 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(1):48-53
BACKGROUND: Methyl N‐phenyl carbamate (MPC) is an intermediate for the preparation of methylene diphenyl diisocyanate (MDI), which is an important monomer for polyurethane synthesis. The synthesis of MPC by the reaction of aniline and dimethyl carbonate (DMC) is becoming more and more attractive. However, most of the catalysts used in MPC synthesis are homogeneous and not environment‐friendly. Therefore, it is important and necessary to develop a new kind of oxide catalyst, that is not only friendly to the environment, but also exhibits higher activity and longer service time. RESULTS: A new heterogeneous catalyst, ZnO‐TiO2, was prepared for MPC synthesis. ZnO‐TiO2 catalyst with a molar ratio Ti/Zn = 2 and calcined at 673 K exhibited good catalytic activity: aniline conversion was 96.9% and MPC yield 66.7%. CONCLUSION: ZnO‐TiO2 exhibits better catalytic activity than ZnO or TiO2 alone, which may result from the formation of ZnTiO3 and Zn2TiO4. Compared with ZnTiO3, Zn2TiO4 has better selectivity for MPC synthesis. Lewis acid sites with weaker acid strength favour MPC synthesis. The catalyst activity can be recovered almost completely by calcination. Copyright © 2008 Society of Chemical Industry 相似文献
16.
Jia-Qi Li Qing-Meng Zhao Yong-Dong Zhou Zong-Yan Zhao 《Journal of the American Ceramic Society》2023,106(5):3009-3023
Effective separation and fast transport of photogenerated carriers are vital links determining the photocatalytic performance. Heterostructure constructed by two complementary semiconductors is a feasible strategy to achieve this goal. By one-pot hydrothermal method, 0D-TiO2 nanoparticles are loaded onto 2D-CuGaO2 nanosheets, forming a mixed dimension, closely combined heterostructure. The photocurrent density of CuGaO2/TiO2 heterostructure is ∼16.6 μA/cm2, which is 1.24 times higher than that of pristine CuGaO2 nanosheets (∼13.4 μA/cm2) and 15 times higher than that of TiO2 (∼1.1 μA/cm2). In the tetracycline hydrochloride degradation experiment, the degradation efficiency of tetracycline hydrochloride by CuGaO2/TiO2 heterostructure reached 99% within 90 min, which was 1.2 times the degradation efficiency of CuGaO2 nanoparticles (82%) and 20.2 times the degradation rate of TiO2 (4.9%). A series of experimental characterizations combined with density functional theory calculations revealed that it is the built-in electric field in the CuGaO2/TiO2 interface region that drives the photogenerated electron–hole pairs to travel in the opposite direction, thus inhibiting their recombination. Furthermore, the energy band offset of the CuGaO2/TiO2 interface makes it easier for the photogenerated holes and electrons to gather onto the valence band of the CuGaO2 nanosheets and the conduction band of the TiO2 nanoparticles, respectively. Therefore, appropriate interface lattice matching, suitable configuration of band gap and band edge positions, and strong opposite drive of interface electric field enable CuGaO2/TiO2 heterostructure to achieve wide spectral response and effective separation of photogenerated electron–hole pairs at the same time. 相似文献
17.
《Ceramics International》2020,46(12):20155-20162
Anatase TiO2 nanoparticles (NPs) were successfully prepared through a hydrothermal approach, and Au NPs at various Au (0.1–2 wt%) contents were photodeposited onto the TiO2 NPs surface. The photocatalytic efficiency for the Au/TiO2 NPs for resorcinol photodegradation throughout UVA illumination was assessed. The TEM images and XPS findings indicated that the Au NPs are highly distributed onto TiO2 surface in the metallic state. The 0.1%Au/TiO2 NPs exhibited the highest photocatalytic efficiency of about 95.34%; however, 72.36% is given by pure TiO2 NPs. It was found that the photodegradation rate of 0.1% Au/TiO2 NPs exhibited 1.5 times of magnitude higher than pure TiO2 NPs. 0.1%Au/TiO2 NPs was considered to be the outstanding photoactive due to the ultimate efficient charge-carriers separation through charge transfer between Au and TiO2 NPs. The Au NPs sizes, its dispersity on TiO2 surface and surface plasmon resonance (SPR) were believed the critical factors for the higher photocatalytic performance of 0.1% Au/TiO2 NPs. The prepared photocatalysts are found to be the promising materials for toxic organic compounds remediation and solar conversion. 相似文献
18.
Sanjib Mondal Chiranjib Ghosh S.M.M. Dhar Dwivedi Anupam Ghosh Sushama Sushama Subhananda Chakrabarti Aniruddha Mondal 《Ceramics International》2021,47(10):14879-14891
Glancing angle deposition (GLAD) was employed to synthesise plasmonic Silver (Ag) nanoparticles (NPs) on the chemically prepared Erbium-doped Titanium dioxide (Er:TiO2) thin films (TFs). The impact of using Ag NPs on the morphological, optical, and electrical aspects of Er:TiO2 TFs were sequentially analysed. From the field emission scanning electron microscopy (FESEM) image, the Ag NPs appeared spherical and uniformly distributed on the Er:TiO2 TFs. The size (diameter) of the maximum number of Ag NPs was ~15 nm (calculated from FESEM image). Energy dispersive X-ray (EDX) spectra assured the presence of Ag NPs on the TFs. X-ray diffraction (XRD) pattern for Ag NPs decorated Er:TiO2 TFs closely resembled the face centred cubic crystal structure of Ag NPs and body centred tetragonal Ag–O compound. The optical spectroscopy (UV–visible diffuse reflectance and photoluminescence) elucidated that the absorption of light was significantly enhanced in the UV–visible spectral range for the TFs in which Ag NPs were sandwiched between Er:TiO2 TF layers (Er:TiO2/Ag NPs/Er:TiO2). The Schottky contact-based Au/Er:TiO2/Si photodetector (PD) and Au/Er:TiO2/Ag NPs/Er:TiO2/Si (plasmonic) PD were constructed. The plasmonic PD offered a better photo-responsivity of ~4.5 fold higher as compared to Er:TiO2 TF-based PD upon 380 nm illumination under ?6 V bias. An increase in detectivity and a decrease in noise equivalent power was observed for the plasmonic device compared to Er:TiO2 device in the UV region. A theoretical approach had been adopted to calculate the wavelength-dependent responsivity for both devices. Further, the important parameters like photoconductive gain, electron transit time and electron mobility were calculated by simulating the experimental responsivity curves of the devices. These parameters exhibited improvement in the UV regime for the plasmonic PD. The fast temporal response with short rise and decay time proves the excellent efficiency of the plasmonic UV PD. 相似文献
19.
Polyaniline/TiO2?SiO2 composites were prepared by an in situ chemical oxidation polymerization approach in the presence of hybrid TiO2?SiO2 fillers. The obtained polyaniline/TiO2?SiO2 composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), thermogravimetry (TG), and current?voltage (I?V) measurements. SEM picture shows a variation in morphology of polyaniline (PANI) from fiber shape to relatively regular particle shape with increasing TiO2?SiO2 contents in the composites. The floccule‐like structures were observed by high resolution TEM, which may help improve the efficiency of conductive network. SEM, XRD, TG, and FTIR spectra all reveal that a relatively strong interaction exist between TiO2?SiO2 and PANI. The I?V characteristics in such composites indicate that the charge transport is mainly governed by the space charge effects, which occurs at the interface between the conducting PANI and TiO2?SiO2. Meanwhile, PANI/TiO2?SiO2 composites exhibit significant increase in conductivity than PANI/TiO2 or PANI/SiO2. The reasons about high conductivity of PANI/TiO2?SiO2 have also been discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2288–2295, 2013 相似文献
20.
Production of Synthesis Gas via Dry Reforming of Methane over Co‐Based Catalysts: Effect on H2/CO Ratio and Carbon Deposition
下载免费PDF全文
![点击此处可从《化学工程与技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ahmed A. Ibrahim Muhammad Awais Naeem Anis H. Fakeeha Wasim Ullah Khan Ahmed S. Al‐Fatesh Ahmed E. Abasaeed 《化学工程与技术》2015,38(8):1397-1405
The effect of support type on synthesis gas production using Co‐based catalysts supported over TiO2‐P25, Al2O3, SiO2, and CeO2 was investigated. The catalysts were prepared by the incipient wet impregnation method and characterized by various techniques for comparison. Experiments were performed in a micro tubular reactor. The results revealed that all Co‐supported catalysts produced synthesis gas ratios of 1 and below and, thus, proved to be well‐suited for methanol and Fischer‐Tropsch syntheses. Co catalysts supported over TiO2‐P25 and Al2O3 provided better synthesis gas ratios and stability performances. The promotion of a Co/TiO2‐P25 catalyst with Ce had a substantial influence on its catalytic activity and the amount of carbon deposit. A Ce‐promoted catalyst diminished markedly the extent of carbon deposition and thus boosted the performance towards better activity and stability. 相似文献