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High-performance/low-temperature-processed dye solar cell counter electrodes based on chromium substrates with cube-like morphology
, Article Journal of Power Sources ; Vol. 260 , 2014 , Pages 299-306 ; ISSN: 03787753 ; Taghavinia, N ; Sharif University of Technology
Abstract
There is still an open question of how to prepare high-performance counter electrodes for dye solar cells (DSCs) at room temperature; a requirement for flexible DSCs. Here, we introduce Pt deposited cube-like chromium coating as a low-temperature highly-efficient counter electrode for DSCs. Cr is a chemically stable metal and can be easily electroplated on conductive substrates with high roughness (here ∼160 nm) and cube-like appearance. A cyclic electrochemical deposition method with optimized temperature and number of cycles is used to grow Pt nanoparticles on this surface and charge transfer resistance as low as 0.54 Ω cm2 and 0.27 Ω cm2 were obtained at 40 °C and 55 °C solution...
The modeling of kinetics and catalyst deactivation in propane dehydrogenation over Pt-Sn/γ-Al2O3 in presence of water as an oxygenated additive
, Article Petroleum Science and Technology ; Vol. 32, issue. 10 , Mar , 2014 , pp. 1139-1149 ; ISSN: 10916466 ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
Abstract
A reduction in catalyst's activity with time-on-stream and the formation of side products are two of the problems associated with catalytic propane dehydrogenation (PDH). Previous studies have indicated that the presence of small amounts of oxygenated additives such as water can reduce coke formation and enhance catalyst activity. The aim of the present work was to develop an appropriate kinetic model for PDH over a commercial Pt-Sn/γ-Al 2O3 catalyst in the presence of small amounts of water. Experimental data were obtained from a previous study where catalytic PDH was carried out in a bench scale reactor system at atmospheric pressure in the temperature range of 575-620°C in the presence of...
Efficient bio-nano hybrid solar cells via purple membrane as sensitizer
, Article BioNanoScience ; Vol. 4, issue. 1 , 2014 , pp. 71-77 ; ISSN: 21911630 ; Molaeirad, A ; Mohamadpour, R ; Khayati, M ; Mehrvand, J ; Sharif University of Technology
Abstract
Bacteriorhodopsin is a heptahelical protein found in the purple membrane of Halobacterium salinarum. The performance of bacteriorhodopsin was evaluated as a sensitizer in dye-sensitized solar cells (DSSCs). Bacteriorhodopsin was efficiently immobilized on the titanium dioxide nanoparticles and then tested for its ability to convert solar radiation to electricity. The photovoltaic performance of DSSC based on the bacteriorhodopsin sensitizer has been examined. Under AM1.5 irradiation, a short-circuit current of 0.28 mA cm−2, open-circuit voltages of 0.51 V, fill factor of 0.62, and an overall energy conversion efficiency of 0.09 % are achieved employing platinum as a counter electrode. Carbon...
Rapid, efficient and selective reduction of aromatic nitro compounds with hydrazine hydrate in the presence of the plain and supported platinum nanoparticles as catalysts
, Article Journal of the Iranian Chemical Society ; Vol. 11, issue. 6 , 2014 , pp. 1587-1592 ; ISSN: 1735207X ; Ahmadi, S. J ; Sadjadi, S ; Outokesh, M ; Sharif University of Technology
Abstract
The current study aimed at application of the plain and supported platinum nanoparticles as a heterogenous catalyst for the reduction of aromatic nitro compounds. Monodispersed platinum nanoparticles were synthesized by reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone as a stabilizer, and then were immobilized on four types of zeolites. The obtained catalyst granules were characterized by X-ray diffractometry and transmission electron microscopy. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. It was found that reaction is adequately rapid at ambient temperature, and by utilizing a...
Construction of Pt nanoparticle-decorated graphene nanosheets and carbon nanospheres nanocomposite-modified electrodes: Application to ultrasensitive electrochemical determination of cefepime
, Article RSC Advances ; Volume 4, Issue 15 , 2014 , Pages 7786-7794 ; ISSN: 20462069 ; Hosseini Nassab, N ; Ghalkhani, M ; Sharif University of Technology
Abstract
A novel ultrasensitive modified electrode was fabricated with a graphene nanosheets and carbon nanospheres (GNS-CNS)-based nanocomposite film as a powerful platform. Pt nanoparticles (PtNPs) were simply electrodeposited onto the GNS-CNS-coated glassy carbon electrode creating a PtNPs/GNS-CNS hybrid nanocomposite modified electrode. Scanning electron microscopy, energy dispersive X-ray spectroscopy and linear sweep voltammetry (LSV) techniques were used for the characterization of the prepared modified electrode. The results of investigation of electrochemical response characteristics of cefepime (CP) revealed a considerable improvement in the oxidation peak current of CP on PtNPs/GNS-CNS/GCE...
Cyclometalated heteronuclear Pt/Ag and Pt/Tl complexes: A structural and photophysical study
, Article Dalton Transactions ; Vol. 43, issue. 3 , 2014 , pp. 1105-1116 ; ISSN: 14779226 ; Ghazfar, R ; Lalinde, E ; Jamshidi, Z ; Samouei, H ; Shahsavari, H. R ; Moreno, M. T ; Escudero-Adan, E ; Benet-Buchholz, J ; Milic, D ; Sharif University of Technology
Abstract
To investigate the factors influencing the luminescent properties of polymetallic cycloplatinated complexes a detailed study of the photophysical and structural properties of the heteronuclear complexes [Pt2Me 2(bhq)2(μ-dppy)2Ag2(μ-acetone) ](BF4)2, 2, [PtMe(bhq)(dppy)Tl]PF6, 3, and [Pt2Me2(bhq)2(dppy)2Tl]PF 6, 4, [bhq = benzo[h]quinoline, dppy = 2-(diphenylphosphino)pyridine] was conducted. Complexes 3 and 4 synthesized by the reaction of [PtMe(bhq)(dppy)], 1, with TlPF6 (1 or 1/2 equiv.) and stabilized by unsupported Pt-Tl bonds as revealed by multinuclear NMR spectroscopy and confirmed by X-ray crystallography for 3. DFT calculations for the previously reported butterfly Pt2Ag2 cluster 2...
Removal of heavy metals from aqueous solution using platinum nanopartcles/Zeolite-4A
, Article Journal of Environmental Health Science and Engineering ; Vol. 12, issue. 1 , 2014 ; ISSN: 2052336X ; Sadjadi, S ; Ahmadi, S. J ; Outokesh, M ; Sharif University of Technology
Abstract
The effects of varying operating conditions on metals removal from aqueous solution using a novel platinum nanopartcles/Zeolite-4A adsorbent are reported in this paper. Characterization of the adsorbent showed successful production of platinum nanopartcles on Zeolite-4A using 3 Wt% platinum. The effects of operation conditions on metals removal using this adsorbent were investigated. The optimal metals adsorption was observed at pH 7, 0.1 g/10 mL dosage and 30 min contact time. Sorption data have been interpreted in terms of Langmuir and Freundlich isotherms
Fabrication of an electrochemical sensor based on the electrodeposition of Pt nanoparticles on multiwalled carbon nanotubes film for voltammetric determination of ceftriaxone in the presence of lidocaine, assisted by factorial-based response-surface methodology
, Article Journal of Solid State Electrochemistry ; Vol. 18, issue. 1 , 2014 , p. 77-88 ; Hosseini-Nassab, N ; Kamalzadeh, Z ; Sharif University of Technology
Abstract
A glassy carbon electrode (GCE) is modified with platinum nanoparticle (PtNPs) decorated multiwalled carbon nanotube (MWCNT). The modified electrode is applied for the determination of ceftriaxone (CFX) in the presence of lidocaine. Different methods were used to characterize the surface morphology of the modified electrode. The electrochemical behavior of CFX was investigated at GCE, MWCNT/GCE and PtNPs/MWCNT/GCE. A factorial-based response-surface methodology was used to find out the optimum conditions with minimum number of experiments. Under the optimized conditions, oxidation peak currents increased linearly with CFX concentration in the range of 0.01-10.00 μM with a detection limit of...
Modeling of coke formation and catalyst deactivation in propane dehydrogenation over a commercial Pt-Sn/γ-Al2O3 catalyst
, Article Petroleum Science and Technology ; Volume 31, Issue 23 , 2013 , Pages 2451-2462 ; 10916466 (ISSN) ; Soltani, M ; Farjoo, A ; Khorasheh, F ; Sharif University of Technology
2013
Abstract
Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al 2O3 catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h-1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant...
Synthesis and characterization of TiO2-graphene nanocomposites modified with noble metals as a photocatalyst for degradation of pollutants
, Article Applied Catalysis A: General ; Volume 462-463 , 2013 , Pages 82-90 ; 0926860X (ISSN) ; Esfandiar, A ; Rahman Setayesh, S ; Habibi Yangjeh, A ; Iraji Zad, A ; Gholami, M. R ; Sharif University of Technology
2013
Abstract
TiO2-graphene (TiO2-GR) nanocomposites were synthesized using photocatalytic reduction method. TiO2-GR nanocomposites were thereafter doped with noble metals (Pt and Pd) by chemical reduction of the corresponding cations. The samples were characterized by different techniques. The addition of GR to TiO2 decreases the crystalline size of TiO2 due to the homogeneous dispersion of the TiO2 nanoparticles on GR sheets and prevention of coagulation of TiO2 nanoparticles during synthesis process. In addition, the surface area of TiO2 was increased by addition of GR and deposition of noble metals which helps to prevent agglomeration of graphene sheets and TiO 2 nanoparticles. Red shifts to the...
Pt and Pd as catalyst deposited by hydrogen reduction of metal salts on WO3 films for gasochromic application
, Article Applied Surface Science ; Volume 273 , May , 2013 , Pages 261-267 ; 01694332 (ISSN) ; Mahdavi, S. M ; Iraji Zad, A ; Sharif University of Technology
2013
Abstract
In this study, tungsten oxide films were deposited by pulsed-laser deposition (PLD) technique. The as-deposited films were annealed at 250 °C in air for 1 h. The surface morphology, microstructure, crystalline phase, and chemical composition of the films were characterized by SEM, XRD and XPS techniques. Pt nanoparticles were deposited onto the tungsten oxide films through a two-step process. First of all, a layer of PtCl2 was coated on the WO3 surface by drop-drying the PtCl2 solution onto the WO3 surface at 60 °C. Consequently, the reduction of the PtCl2 into the metallic Pt nanoparticles was performed at 200 °C. In this study, the effect of the temperature during hydrogen reduction of...
Investigation of carbon monoxide tolerance of platinum nanoparticles in the presence of optimum ratio of doped polyaniline with para toluene sulfonic acid and their utilization in a real passive direct methanol fuel cell
, Article Electrochimica Acta ; Volume 97 , 2013 , Pages 216-225 ; 00134686 (ISSN) ; Amani, M ; Pahlavanzadeh, H ; Kazemeini, M ; Sharif University of Technology
2013
Abstract
Polyaniline fiber (PANI) was synthesized by chemical interfacial method and doped with para toluene sulfonic acid (PTSA) through a sequential doping-dedoping-redoping process resulting in PANI-PTSA. The doped material was utilized to fabricate Vulcan-polyaniline composite of C-PANI-PTSA. Next, through reduction, Pt particles were deposited on to this composite to produce a Pt/C-PANI-PTSA electrocatalyst. To investigate the PANI-PTSA interaction with the carbon support as well as, to consider its effect upon the catalytic activity of Pt/C-PANI-PTSA, electrocatalysts with different ratios of 10, 15, 20, 25 and 30 wt% were synthesized and their activity was compared with the Pt/C (Electrochem)....
Electrodeposition and electrocatalytic properties of Pt/Ni-Co nanowires for non-enzymatic glucose detection
, Article Journal of Alloys and Compounds ; Volume 554 , 2013 , Pages 169-176 ; 09258388 (ISSN) ; Mahshid, S ; Dolati, A ; Ghorbani, M ; Yang, L ; Luo, S ; Cai, Q ; Sharif University of Technology
2013
Abstract
A nanowire arrays system consisting of an ordered configuration of Pt, Ni and Co was constructed in single-bath solution through pulse electrodeposition. This structure was evaluated as a potential amperometric non-enzymatic sensor to detect glucose in alkaline solution. We observed a strong and fast amperometric response at low applied potential of 0.4 V vs. SCE over linear ranges of 0-0.2 mM and 0.2-8 mM glucose with sensitivities of 1125 and 333 μA mM-1 cm-2, respectively. We also observed a low detection limit for glucose of 1 μM. Correlation of the electronic and geometric modifications with the electrochemical performance characteristics enhanced catalytic activity of the electrode by...
Resonant optical absorption and defect control in Ta3N 5 photoanodes
, Article Applied Physics Letters ; Volume 102, Issue 3 , 2013 ; 00036951 (ISSN) ; Van De Krol, R ; Sharif University of Technology
2013
Abstract
In this study, we explore resonance-enhanced optical absorption in Ta 3N5 photoanodes for water splitting. By using a reflecting Pt back-contact and appropriate Ta3N5 film thickness, the resonance frequency can be tuned to energies just above the bandgap, where the optical absorption is normally weak. The resonance results in a significant improvement in the photoanode's incident photon-to-current efficiency. The Ta3N5 films are made by high-temperature nitridation of Ta2O5. The nitridation time is found to be critical, as extended nitridation result in the formation of nitrogen vacancies through thermal reduction. These insights give important clues for the development of efficient...
A study of hydrated nanostructured tungsten trioxide as an electroactive material for pseudocapacitors
, Article Ionics ; Volume 19, Issue 2 , May , 2013 , Pages 287-294 ; 09477047 (ISSN) ; Gobal, F ; Barzgari, Z ; Sharif University of Technology
2013
Abstract
Agglomerates of tungsten trioxide in the range of 90 nm to 1 μm are prepared by the acid precipitation method and characterized by XRD as well as scanning electron microscopy. The product when coated with platinum showed pseudocapacitance when in contact with acidic electrolyte in the potential range of 0. 1 to -0. 25 V/SCE. Capacitance in the range of 0. 014 to 0. 039 F cm-2 exhibiting moderate potential dependencies measured through both chronopotentiometry and impedance spectroscopy is presumed to be due to the insertion/de-insertion of protons into the lattice of tungsten trioxide. Equivalent circuit consisting of parallel simulators of mass transfer and capacitor charging...
Preparation and characterization of visible light sensitive nano titanium dioxide photocatalyst
, Article Scientia Iranica ; Volume 19, Issue 6 , December , 2012 , Pages 1626-1631 ; 10263098 (ISSN) ; Kazemeini, M ; Fattahi, M ; Sharif University of Technology
2012
Abstract
Dye sensitizers loaded on TiO2 decrease the electron excitation energy, thereby improving the photocatalytic performance by causing an increase in sensitivity under visible light irradiation. Three dye sensitizer precursors, Mordant Orange 1, N3 (red dye) and Cobalt (II) Phthalocyanine Tetrasulfonate (CoPcTs), were utilized to load the photocatalyst. The rate of the electron trapping process on platinum is clearly compatible with the migration rate of boundary electrons. Consequently, the migration of boundary electrons from the conduction band towards electron acceptors is increased by loading platinum onto the titanium dioxide. In this research, TiO2 was synthesized from a titanium...
Modeling of platinum extraction from used reforming catalyst in iodine solutions
, Article ECS Transactions ; Volume 41, Issue 17 , 2012 , Pages 45-51 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Baghallha, M ; Sharif University of Technology
Abstract
Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95°C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to PtI6 2- and the precipitation of the dissolved platinum to PtI 4(s) was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction...
Kinetics of chemical ordering in a Ag-Pt nanoalloy particle via first-principles simulations
, Article Journal of Chemical Physics ; Volume 137, Issue 19 , 2012 ; 00219606 (ISSN) ; Taherkhani, F ; Parsafar, G ; Caro, A ; Fortunelli, A ; Sharif University of Technology
2012
Abstract
The energetics and kinetic energy barriers of vacancy/atom exchange in a 37-atom truncated octahedron Ag-Pt binary cluster in the Ag-rich range of compositions are investigated via a first-principles atomistic approach. The energy of the local minima obtained considering various distributions of a single vacancy and a few Pt atoms within the cluster and the energy barriers connecting them are evaluated using accurate density-functional calculations. The effects of the simultaneous presence of a vacancy and Pt atoms are found to be simply additive when their distances are larger than first-neighbors, whereas when they can be stabilizing at low Pt content due to the release of strain by the...
Platinum extraction from spent catalysts by TOPO utilizing RSM technique
, Article Advanced Materials Research ; Volume 548 , 2012 , Pages 186-192 ; 10226680 (ISSN) ; 9783037854532 (ISBN) ; Kazemeini, M ; Fattahi, M ; Sharif University of Technology
2012
Abstract
In this research, data on liquid-liquid extraction of platinum from commercial spent catalysts by trioctylphosphine oxide (TOPO) in toluene were experimentally obtained. Alkaline metal salts were used to optimize the separation process. Best Salting-out effect was obtained by KCl which extracted up to 90% of platinum utilizing TOPO. Furthermore, extraction percentages of Pt and Al depending upon different factors were investigated. It was observed that the extraction process was kinetically fast and achieving the equilibrium time took less than 30 seconds. Optimized points obtained utilizing response surface methodology (RSM) by the "Design Expert" software in order to minimize the...
Kinetic modeling of propane dehydrogenation over an industrial catalyst in the presence of oxygenated compounds
, Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 107, Issue 1 , 2012 , Pages 141-155 ; 18785190 (ISSN) ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
Springer
2012
Abstract
The aim of this study was to develop an appropriate kinetic model for propane dehydrogenation (PDH) over an industrial Pt-Sn/γ-Al 2O 3 catalyst in the presence of small amounts of oxygenated compounds. Experimental data were obtained from a previous study where catalytic PDH was carried out in a laboratory scale reactor at atmospheric pressure in the temperature range of 575-620 °C in the presence of small amounts of water or methanol. The kinetics of the main dehydrogenation reaction was described and the effects of water and methanol on coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amount of added...