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Controlled optical near-field growth of individual free-standing well-oriented carbon nanotubes, application for scattering SNOM/AFM probes
, Article Nanophotonics ; Volume 11, Issue 21 , 2022 , Pages 4671-4686 ; 21928614 (ISSN) ; Heydarian, H ; Rashidian, B ; Sharif University of Technology
De Gruyter Open Ltd
2022
Abstract
Exploiting localized heat-generation density and the resulting enhanced temperature-rise for controlled growth of carbon nanotubes (CNTs) is reported, and its potentials for batch-production of high-quality CNT probes are demonstrated. Optical near field chemical vapor deposition (ONF-CVD) benchtop fabrication schemes are developed for the localized integration of individual well-aligned carbon nanotubes without bending/buckling exactly at desired nanoscale sites. It is demonstrated that generating self-aligned catalyst nanoparticles superimposed on top of silicon nanotips, along with near-field induced absorption confinement, provide the ability to localize the generated heat at the...
Optimization of selenization process to remove Ga-induced pin-holes in CIGS thin films
, Article Solar Energy ; Volume 236 , 2022 , Pages 175-181 ; 0038092X (ISSN) ; Dehghani, M ; Tehrani, N. A ; Taghavinia, N ; Bagherzadeh, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In thin-film solar cells, deposition of pinhole and the crack-free absorber layer, with the right chemical stoichiometry is highly important for high-performance solar cell devices. In solution-based CIGS solar cell technology, a nanoparticle ink approach provides phase stability of the final chalcogenide absorber layer. However, the sintering of small nanoparticles to form large grains with reduced grain boundaries is an important challenge in the fabrication process. This is usually realized by annealing in the Se atmosphere, i.e. selenization process. However, the presence of Ga in CIGS films leads to pinholes after selenization. In this study, the synthesis and deposition of high-quality...
Shape-Controlled photochemical synthesis of noble metal nanocrystals based on reduced graphene oxide
, Article ACS Applied Materials and Interfaces ; Volume 14, Issue 14 , 2022 , Pages 16527-16537 ; 19448244 (ISSN) ; Naseri, A ; Li, T ; Ostovan, A ; Asadian, E ; Jia, R ; Shi, L ; Huang, L ; Moshfegh, A. Z ; Sharif University of Technology
American Chemical Society
2022
Abstract
The fabrication of supported noble metal nanocrystals (NCs) with well-controlled morphologies have been attracted considerable interests due to their merits in a wide variety of applications. Photodeposition is a facile and effective method to load metals over semiconductors in a simple slurry reactor under irradiation. By optimizing the photodeposition process, the size, chemical states, and the geometrical distribution of metal NCs have been successfully tuned. However, metal NCs with well-controlled shapes through the photodeposition process have not been reported until now. Here, we report our important advances in the controlled photodeposition process to load regular noble metal NCs....
Cobalt vanadium chalcogenide microspheres decorated with dendrite-like fiber nanostructures for flexible wire-typed energy conversion and storage microdevices
, Article Nanoscale ; Volume 14, Issue 25 , 2022 , Pages 9150-9168 ; 20403364 (ISSN) ; Shahrokhian, S ; Sharif University of Technology
Royal Society of Chemistry
2022
Abstract
The increasing energy demand for next-generation portable and miniaturized electronics has drawn tremendous attention to develop microscale energy storage and conversion devices with light weight and flexible characteristics. Herein, we report the preparation of flower-like cobalt vanadium selenide/nickel copper selenide (CoVSe/NiCuSe) microspheres with three-dimensional hierarchical structure of micropore growth on copper wire for a flexible fiber microsupercapacitor (microSC) and overall water splitting. The CoV-LDH microspheres are anchored on the dendrite-like NiCu nanostructured Cu wire using a hydrothermal method (CoV-LDH/NiCu@CW). The sulfidation and selenization of CoV-LDH/NiCu was...
Enhanced Broadband Photoresponsivity of the CZTS/WSe2Heterojunction by Gate Voltage
, Article ACS Applied Electronic Materials ; Volume 4, Issue 12 , 2022 , Pages 6189-6203 ; 26376113 (ISSN) ; Vardast, S ; Esfandiar, A ; Iraji Zad, A ; Heidariramsheh, M ; Sharif University of Technology
American Chemical Society
2022
Abstract
High-performance photodetectors play critical roles in numerous photon-based applications in imaging, communication, and energy harvesting. Nowadays, heterostructures have received significant attention to extend the performance of photodetectors, with exceptionally high optical absorption and a wide absorption range. However, the enhancement factors, exact mechanism, and facile fabrication procedures are long-standing problems. Here, a heterojunction of a two-dimensional chemical vapor deposition-grown monolayer of WSe2with a Cu2ZnSnS4(CZTS) film is introduced. The CZTS film as an abundant material was synthesized in the form of nanoparticles, and it showed a great effect on the enhancement...
Low loaded MoS2/Carbon cloth as a highly efficient electrocatalyst for hydrogen evolution reaction
, Article International Journal of Hydrogen Energy ; Volume 47, Issue 3 , 2022 , Pages 1579-1588 ; 03603199 (ISSN) ; Mehdipour, H ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Active edge sites of MoS2 nanosheets exhibit promising futures for hydrogen evolution reaction (HER), comparable with remarkable performances of highly cost platinum. However, 3D structures of MoS2 suffer from a lack of high mobility and unexposed active sites which lower the electrocatalytic activity. In this study, we show that there is a balance between increasing the active sites on the one hand and managing the charge transfer to facilitate the reaction on the other hand, and achieving this balance increases the efficiency of the electrocatalyst tremendously. For this purpose, we directly attached exfoliated MoS2 nanosheets onto carbon cloth (CC) substrate as a 3D network of conductive...
Core–Shell nanophotocatalysts: review of materials and applications
, Article ACS Applied Nano Materials ; Volume 5, Issue 1 , 2022 , Pages 55-86 ; 25740970 (ISSN) ; Rabiee, N ; Ahmadi, S ; Baneshi, M ; Khatami, M ; Iravani, S ; Varma, R. S ; Sharif University of Technology
American Chemical Society
2022
Abstract
Hybrid nanostructures and nanoarchitectures possess unique physicochemical properties such as high activity/functionality, enhanced physicochemical stability, and improved biocompatibility, which renders them suitable for various biomedical, pharmaceutical, environmental, and catalytic applications. In this context, core–shell nanophotocatalysts have shown superior activity compared to their counterparts, namely, their individual pristine semiconductors and composite materials components. Thus, the development of various innovative core–shell nanostructures as photocatalysts is of practical relevance in view of their unique properties with salient advantageous features applicable to, among...
Influence of adding a modified zeolite-Y onto the NiMo/Al2O3 catalyst utilized to produce a diesel fuel with highly reduced sulfur content
, Article Microporous and Mesoporous Materials ; Volume 332 , 2022 ; 13871811 (ISSN) ; Kazemeini, M ; Soltanali, S ; Rashidzadeh, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In order to make a Na–Y zeolite with Si/Al ratio of 2.27 more acidic with a higher volume of mesopores, a combination of different and consecutive methods including; chemical (i.e.; utilizing different compounds, such as NH4F and EDTA) and thermal/hydrothermal (i.e.; implementing calcination/steaming) methods, were employed for modification and dealumination. The combination of acidic-hydrothermal dealumination method led to a further structural collapse compared to that of the acidic calcination. In comparison with the other dealumination methods, the fluorination strategy (i.e.; utilizing NH4F) resulted in a zeolite with higher crystallinity, acidity, and specific surface area. The...
Aperiodic perforated graphene in optical nanocavity absorbers
, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 276 , 2022 ; 09215107 (ISSN) ; Akhavan, O ; Salami, P ; Yousefi, L ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Aperiodic perforated graphene layers were synthesized and used in fabrication of optical nanocavity absorbers. Chemical vapor deposition-grown graphene (Gr) layers were exposed to oxygen plasma etching to obtain the perforated graphene (pGr). The fabricated pGr/SiO2 (68 nm)/Ag (150 nm) nanocavity could present significant higher optical absorption, especially at around 530 nm wavelength region, as compared to a benchmark Gr/SiO2 (68 nm)/Ag (150 nm) sample. The effect of pore size of the pGr layer on the absorption property of the nanocavity has been studied by both experimental and numerical methods. The dependence of the absorption property of the nanocavity on the incident angles of...
Thermodynamic analysis of application of organic Rankine cycle for heat recovery from an integrated DIR-MCFC with pre-reformer
, Article Energy Conversion and Management ; Volume 67 , 2013 , Pages 197-207 ; 01968904 (ISSN) ; Khazaeli, A ; Roshandel, R ; Panjeshahi, M. H ; Sharif University of Technology
2013
Abstract
This work deals with waste heat recovery from a proposed direct internal reforming molten carbonate fuel cell (DIR-MCFC), including an integrated pre-reformer. In this regard, some advantages are attainable over exhaust gas recycling. For instance, due to low temperature in the pre-reformer, carbon deposition and coke formation resulting from higher hydrocarbons can be eliminated. In this study, the cathode outlet provides the heat requirement for the pre-reforming process. After partial heat recovery from the cathode outlet, the stream still has a considerable energy and exergy (352.55 °C and 83.687 kW respectively). This study investigates waste heat recovery from the proposed DIR-MCFC,...
A comparative study of the electrooxidation of C1 to C3 aliphatic alcohols on Ni modified graphite electrode
, Article Science China Chemistry ; Volume 55, Issue 9 , 2012 , Pages 1819-1824 ; 16747291 (ISSN) ; Mirzapoor, A ; Danaee, I ; Shahnazi, S. A. A ; Gobal, F ; Sharif University of Technology
Abstract
Nickel modified graphite electrodes (G/Ni) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol, ethanol, 1-propanol and 2-propanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, the electrochemical response, peak current varied in the order of MeOH > EtOH > 1-PrOH > 2-PrOH. Under the CA regime, a higher catalytic rate constant obtained for methanol oxidation was in agreement with CV measurements. Lower charge transfer resistance was obtained for low carbon alcohols oxidation and significantly higher...
Investigation on asphaltene deposition mechanisms during CO2 flooding processes in porous media: A novel experimental study and a modified model based on multilayer theory for asphaltene adsorption
, Article Energy and Fuels ; Volume 26, Issue 8 , 2012 , Pages 5080-5091 ; 08870624 (ISSN) ; Ghotbi, C ; Taghikhani, V ; Shahrabadi, A ; Sharif University of Technology
2012
Abstract
In this paper, oil recovery and permeability reduction of a tight sandstone core sample in miscible CO2 flooding processes due to asphaltene deposition were studied using an Iranian bottom hole live oil sample in order to distinguish between the mechanical plugging and adsorption mechanisms of asphaltene involved in the interfacial interaction of the asphaltene/mineral rock system. A novel experimental method was designed and proposed to measure the amount of deposited asphaltene due to different mechanisms using the cyclohexane or toluene reverse flooding and spectrophotometer. In this work, the bottom hole live oil sample was injected first to a long core and then CO 2 injection was...
Mesoporous submicrometer TiO 2 hollow spheres as scatterers in dye-sensitized solar cells
, Article ACS Applied Materials and Interfaces ; Volume 4, Issue 6 , 2012 , Pages 2964-2968 ; 19448244 (ISSN) ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
2012
Abstract
Hierarchical submicrometer TiO 2 hollow spheres with outer diameter of 300-700 nm and shell thickness of 200 nm are synthesized by liquid phase deposition of TiO 2 over carbon microspheres as sacrificial templates. The final TiO 2 hollow spheres are applied as a scattering layer on top of a transparent nanocrystalline TiO 2 film, serving as the photoanode of a dye-sensitized solar cell (DSC). In addition to efficient light scattering, the mesoporous structure of TiO 2 hollow spheres provides a high surface area, 74 m 2/g, which allows for higher dye loading. This dual functioning suggests that TiO 2 hollow spheres may be good replacements for conventional TiO 2 spheres as scatterers in DSCs....
Simulation of activity loss of fixed bed catalytic reactor of MTO conversion using percolation theory
, Article Chemical Engineering Science ; Volume 66, Issue 23 , December , 2011 , Pages 6199-6208 ; 00092509 (ISSN) ; Khorasheh, F ; Sharif University of Technology
2011
Abstract
In this investigation, a reactor model for prediction of the deactivation behavior of MTO's porous catalyst in a fixed bed reactor is developed. Effect of coking on molecular transport in the porous structure of SAPO-34 has been simulated using the percolation theory. Thermal effects of the reaction were considered in the model and the temperature profile of the gas stream in the reactor was predicted. The predicted loss in catalyst activity with time-on-stream was in very good agreement with the experimental data. The resulting coke deposition and gas temperature profiles along the length of reactor suggested a reaction front moving toward the outlet of the fixed bed reactor at the...
Palladium nanoparticle deposition onto the WO3 surface through hydrogen reduction of PdCl2: Characterization and gasochromic properties
, Article Solar Energy Materials and Solar Cells ; Volume 95, Issue 8 , August , 2011 , Pages 2335-2340 ; 09270248 (ISSN) ; Fardindoost, S ; Mahdavi, S. M ; Iraji Zad, A ; Tahmasebi G. N ; Sharif University of Technology
2011
Abstract
Nowadays, gasochromic Pd/WO3 coatings as optically switchable materials have become more applicable for hydrogen sensors and smart windows. In this study, WO3 films were prepared by Pulsed Laser Deposition (PLD) and spin-coating sol-gel techniques. For deposition of Pd, first a layer of PdCl2 was obtained via a simple drop-drying process by dropping PdCl2 solution onto WO3 substrates and drying them at room temperature. Then Pd nanoparticles were synthesized via hydrogen gas exposure that causes reduction of the PdCl2 layer. According to Scanning Electron Microscope (SEM) observations before hydrogen reduction, many individual nanoparticles or fractal-like constructions of palladium were...
Localized surface plasmon resonance of Cu@Cu2O coreshell nanoparticles: Absorption, scattering and luminescence
, Article Physica B: Condensed Matter ; Volume 406, Issue 13 , July , 2011 , Pages 2678-2683 ; 09214526 (ISSN) ; Vesaghi, M. A ; Sharif University of Technology
2011
Abstract
By co-deposition via RF-Sputtering and RF-PECVD methods and using Cu target and acetylene gas, we prepared Cu@Cu2O coreshell nanoparticles on the a-C:H thin film at room temperature. Mie absorption of Cu cores, scattering from Cu2O shell and luminescence that rises from carrier transfer in Cu@Cu2O interface were employed to fit the whole range of visible extinction spectrum of these coreshells. From simulation it was found that scattering and luminescence have an important effect on the energy, width and shape of LSPR absorption peak. Shift of LSPR peak is more affected by the dielectric coefficient of shell than Cu core size particularly for Cu core diameter above 4 nm. Also, the LSPR...
Comparative study of ZnO nanostructures grown on silicon (1 0 0) and oxidized porous silicon substrates with and without Au catalyst by chemical vapor transport and condensation
, Article Journal of Alloys and Compounds ; Volume 509, Issue 11 , March , 2011 , Pages 4295-4299 ; 09258388 (ISSN) ; Dariani, R. S ; Zad, A. I ; Sharif University of Technology
2011
Abstract
ZnO tetrapods and rods were grown on silicon and thermally oxidized porous silicon substrates with and without Au catalyst layer by carbothermal reduction of ZnO powder through chemical vapor transport and condensation method (CVTC). Porous silicon was fabricated by electrochemical etching of silicon in HF solution. The effect of substrates on morphology, structure and photoluminescence spectra of ZnO nanostructures has been studied. The texture coefficient (TC) of each sample was calculated from XRD data that demonstrated random orientation of ZnO nanostructures on the oxidized porous silicon substrate. Moreover, TC indicates the effect of Au catalyst layer on formation of more highly...
Visible light active Au:TiO2 nanocomposite photoanodes for water splitting: Sol-gel vs. sputtering
, Article Electrochimica Acta ; Volume 56, Issue 3 , January , 2011 , Pages 1150-1158 ; 00134686 (ISSN) ; Sangpour, P ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
In this study, pure TiO2 and Au:TiO2 nanocomposite thin films are both synthesized using sol-gel and RF reactive co-sputtering methods. Physical and photoelectrochemical properties of the thin films deposited by each method are compared. The optical density spectra and scanning electron microscopy images of the Au:TiO2 films reveal formation of gold nanoparticles in the all nanocomposite films synthesized by two methods. Moreover, the optical bandgap energy of the thin films decreases with addition of Au nanoparticles. X-ray photoelectron spectroscopy indicates that the presence of gold in metallic state and the formation of TiO2 is stoichiometric. The photoelectrochemical properties of the...
Supercritical synthesis and in situ deposition of PbS nanocrystals with oleic acid passivation for quantum dot solar cells
, Article Materials Chemistry and Physics ; Volume 156 , 2015 , Pages 163-169 ; 02540584 (ISSN) ; Simchi, A ; Aashuri, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Colloidal quantum dot solar cells have recently attracted significant attention due to their low-processing cost and surging photovoltaic performance. In this paper, a novel, reproducible, and simple solution-based process based on supercritical fluid toluene is presented for in situ growth and deposition PbS nanocrystals with oleic-acid passivation. A lead precursor containing sulfur was mixed with oleic acid in toluene and processed in a supercritical fluid condition at different temperatures of 140, 270 and 330 °C for 20 min. The quantum dots were deposited on a fluorine-doped tin oxide glass substrate inside the supercritical reactor. Transmission electron microscopy, X-ray diffraction,...
Optimal deployment of renewable electricity technologies in Iran and implications for emissions reductions
, Article Energy ; Volume 91 , 2015 , Pages 882-893 ; 03605442 (ISSN) ; Shafiei, E ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this paper, special focus is paid to the long-term adoption of renewable electricity technologies and their implications for emissions reductions in Iran. MESSAGE, as a bottom-up energy supply optimization model, is used to assess the lowest-cost technology options. The potential impacts of transitioning to a renewable electricity supply are quantified, and the investment requirement to achieve a low-carbon generation mix is estimated. Alternative scenarios are defined to evaluate the impact of fossil fuel prices, the carbon tax and government incentives on the utilization of renewable resources, national renewable targets, and emissions reductions. The prioritization of non-hydro...