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51.
Naveen V. Kulkarni Soumen Karmakar Srinanadan N. Asthana Ashok B. Nawale Arif Sheikh Shashikant P. Patole J. B. Yoo Vikas L. Mathe Ashok K. Das Sudha V. Bhoraskar 《Journal of Materials Science》2011,46(7):2212-2220
This article addresses the growth of hollow nanocrystalline particles of γ-alumina by the post-oxidation of nano-aluminium
particles in air. The nanoparticles of aluminium were synthesized in a DC-transferred arc thermal plasma reactor. The as-synthesized
nano-aluminium particles were oxidized, in air, at different temperatures. The as-synthesized parent nano aluminium and their
daughter nanoparticles of aluminium oxide were thoroughly characterized with the help of X-ray diffraction analysis, high
resolution transmission electron microscopy and thermogravimetric analysis. Two-step oxidation behaviours, unique in nanoparticles,
are found to be the main driving force behind the formation of hollow spherical structures. The entire phenomenon is compared
with the oxidation behaviour of coarse grain aluminium. The content of γ-alumina, identified by X-ray diffraction, relative
to that of unreacted aluminium, has increased almost exponentially with the oxidation temperature in the case of nano aluminium.
Similar behaviour is not observed in the case of coarse grain aluminium. The crystalline features of alumina, forming the
walls of the hollow sphere, were confirmed by high resolution transmission electron microscopy. 相似文献
52.
Nonhlanhla E. Mphahlele Lukas Le Roux Charl J. Jafta Leskey Cele Mkhulu K. Mathe Tebello Nyokong Nagao Kobayashi Kenneth I. Ozoemena 《Journal of Materials Science》2014,49(1):340-346
The photoelectrochemistry of metallo-octacarboxyphthalocyanines (MOCPc, where M = Zn or Si(OH)2) integrated with MWCNTs for the development of dye-sensitized solar cells (DSSCs) is reported. The DSSC performance (obtained from the photo-chronoamperometric and photo-impedimetric data) decreased as ZnOCPc > (OH)2SiOCPc. The incorporation of the MWCNTs on the surface of the TiO2 film (MOCPc–MWCNT systems) gave higher photocurrent density than the bare MOCPc complexes. Also, from the EIS results, the MOCPc–MWCNT hybrids gave faster charge transport kinetics (approximately three times faster) compared to the bare MOCPc complexes. The electron lifetime was slightly longer (ca. 6 ms) at the ZnOCPc systems than at the (OH)2SiOCPc system (ca. 4 ms) meaning that the presence of the MWCNTs on the surface of the TiO2 film did not show any significant improvement on preventing charge recombination process. 相似文献
53.
Schottky solar cells fabricated on 10, 20 and 30 μm epitaxial silicon produce a current density ranging from about 10–22 mA/cm2, depending on Si thickness and orientation, in close agreement with theoretically predicted data. These results are also in close agreement with recent data on p-n solar cells, using thin epitaxial silicon. Data reported herein predict that 10% efficient Schottky solar cells could be produced using about 20 μ of silicon on a suitable substrate. A 7.6% efficient Schottky solar cell on epitaxial silicon has been recently fabricated and tested using AM1 sunlight (100 mW/cm2). 相似文献
54.
K.K. Patankar V.L. Mathe A.N. Patil S.A. Patil S.D. Lotke Y.D. Kolekar P.B. Joshi 《Journal of Electroceramics》2001,6(2):115-122
Magnetoelectric composites of CuFe1.8Cr0.2O4– Ba0.8Pb0.2TiO3 were prepared using high temperature solid-state reaction technique. X-ray structural analysis of these composites confirms the presence of both the phases in the composite. Detailed studies of dielectric properties (, tan and
ac
) as a function of frequency (100 Hz to 1 MHz) and temperature (30°C to 250°C) show that these compounds exhibit diffuse ferroelectric phase transitions. Results of ac conductivity, dc resistivity and thermoelectric power measurements show that conduction occurs by hopping of charge carriers. The magnetoelectric effect has been studied as a function of intensity of magnetic field. The electrical polarisation was induced in piezoelectric (Ba0.8Pb0.2TiO3) phase as result of strain induced in the ferrite (CuFe1.8Cr0.2O4) phase by the applied magnetic field. The Jahn-Teller distortion caused in the ferrite lattice by Jahn-Teller ions like Cu2+ and Cr3+ is also responsible for the elastic coupling of strain to the Ba0.8Pb0.2TiO3 phase. 相似文献
55.
56.
Polycrystalline thin films ofn-CdIn2S4 have been spray deposited onto amorphous and fluorinedoped tin oxide (FTO) coated glass substrates at the optimized substrate
temperature of 380°C. The films were characterized by X-ray diffraction (XRD) and optical absorption studies. XRD studies
revealed that the films were polycrystalline with spinel cubic structure. The optical absorption studies showed the band gap
energy to be 2·14 eV. Photoelectrochemical (PEC) investigations were carried out using cell configurationn-CdIn2S4/1 M NaOH+1 M Na2S+1 M S/C. Using Butler model, the optical band gap and minority carrier diffusion length (L
P) were found to be 2·22 eV and 0·07 μm, respectively. Gartner’s model was used to calculate the minority carrier diffusion
length and the donor concentration (N
D) for CdIn2S4 films at three different wavelengths.N
D was found to be of the order of 1016 cm−3. 相似文献
57.
Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts for ethanol electro-oxidation in alkaline medium 总被引:2,自引:0,他引:2
R. Mmalewane Modibedi Thembelihle MasombukaMkhulu K. Mathe 《International Journal of Hydrogen Energy》2011,36(8):4664-4672
Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium was studied by cyclic, carbon monoxide stripping voltammetries and chronoamperometry. The current density obtained for the electro-oxidation was affected by varying ethanol concentration between 0.25 and 4 M. Raising ethanol concentration up to 3 M increased the coverage of the adsorbed ethoxy (CH3COads) species on the nanocatalyst surface, thus yielding an increase in current density. Pd-Sn/C displayed better electrocatalytic activity and stability towards poisoning than Pd-Ru-Sn/C and Pt-Ru/C (E-TEK Inc.) nanocatalysts. Transmission electron microscopy results showed that Pd-Sn and Pd-Ru-Sn nanoparticles were uniformly dispersed on carbon support. The average particle size of Pd-Sn was 7 ± 0.5 nm in diameter while for Pd-Ru-Sn was 6 ± 0.7 nm. 相似文献
58.
Ntombizodwa R. Mathe Manfred R. Scriba Neil J. Coville 《International Journal of Hydrogen Energy》2014
Bimetallic Pt nanoparticles were prepared by alloying Pt with the non-noble transition metals, Co and Ni, using a conventional heat-treatment (HT) method and microwave-irradiation (MW). The resulting samples were Pt–Co-Ht, Pt–Ni-HT, Pt–Co, MW and Pt–Ni-MW. The aim was to evaluate the electrocatalytic behaviour and surface properties of the materials based on the alloying metal used and the synthesis process. XRD studies of the nanoparticles indicated that alloyed structures were formed for the microwave (MW) synthesized samples, as seen by a decrease in the lattice parameters. Using X-ray photoelectron spectroscopy analysis, surface segregation of Co and Ni occurred (1:4 surface atomic ratio Pt–Co or Ni) for the Pt–Co-MW and Pt–Ni-MW samples. In contrast the heat-treated Pt–Ni catalyst showed Pt surface segregation. Methanol oxidation reaction (MOR) studies revealed an increase in the electrocatalytic activity upon the addition of Co and Ni to Pt when compared to a monometallic Pt catalyst. The presence of oxide and hydroxide alloying metal species is suggested to be the cause of the observed enhancement in the catalytic activity. Overall the Pt–Ni-MW catalyst displayed the best MOR activity and this is attributed to the large amounts of Ni-hydroxide species observed on the catalyst surface. 相似文献
59.
Jianwei Ren Nicholas M. Musyoka Henrietta W. Langmi Tshiamo Segakweng Brian C. North Mkhulu Mathe Xiangdong Kang 《International Journal of Hydrogen Energy》2014
Modulated synthesis of MIL-101(Cr) in high yield and with good reproducibility using formic acid as a modulator is reported. Higher molar ratio of formic acid/CrCl3 was found to form better shape-defined MIL-101(Cr) crystals with higher surface area, larger pore volume and better hydrogen uptake performance. The highly crystalline MIL-101(Cr), composed of crystals in the size range of 100–150 nm with multifaceted surface, could be obtained in an optimized molar regime of CrCl3·6H2O/H2BDC/100HCOOH/550H2O at 210 °C for 8 h. The MIL-101(Cr) obtained from the modulated synthesis also showed high thermal and moisture stabilities as well as enhanced hydrogen storage capacity, making this material particularly promising for practical hydrogen storage applications. 相似文献
60.
Krisztina S. Nagy Krisztina Toth Eva Pallinger Angela Takacs Laszlo Kohidai Angela Jedlovszky-Hajdu Domokos Mathe Noemi Kovacs Daniel S. Veres Krisztian Szigeti Kristof Molnar Eniko Krisch Judit E. Puskas 《International journal of molecular sciences》2021,22(19)
This paper focuses on preliminary in vitro and in vivo testing of new bivalent folate-targeted PEGylated doxorubicin (DOX) made by modular chemo-enzymatic processes (FA2-dPEG-DOX2). A unique feature is the use of monodisperse PEG (dPEG). The modular approach with enzyme catalysis ensures exclusive γ-conjugation of folic acid, full conversion and selectivity, and no metal catalyst residues. Flow cytometry analysis showed that at 10 µM concentration, both free DOX and FA2-dPEG-DOX2 would be taken up by 99.9% of triple-negative breast cancer cells in 2 h. Intratumoral injection to mice seemed to delay tumor growth more than intravenous delivery. The mouse health status, food, water consumption, and behavior remained unchanged during the observation. 相似文献