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    Comparison of trap-state distribution and carrier transport in nanotubular and nanoparticulate TiO2 electrodes for dye-sensitized solar cells

    , Article ChemPhysChem ; Volume 11, Issue 10 , July , 2010 , Pages 2140-2145 ; 14394235 (ISSN) Mohammadpour, R ; Zad, A. I ; Hagfeldt, A ; Boschloo, G ; Sharif University of Technology
    Dye-sensitized solar cells (DSCs) with nanotubular TiO2 electrodes of varying thicknesses are compared to DSCs based on conventional nanoparticulate electrodes. Despite the higher degree of order in one-dimensional nanotubular electrodes, electron transport times and diffusion coefficients, determined under short-circuit conditions, are comparable to those of nanoparticulate electrodes. The quasi-Fermi level, however, is much lower in the nanotubes, suggesting a lower concentration of conduction band electrons. This provides evidence for a much higher diffusion coefficient for conduction band electrons in nanotubes than in nanoparticulate films. The electron lifetime and the diffusion length... 

    Adsorption of pollutant cations from their aqueous solutions on graphitic carbon nitride explored by density functional theory

    , Article Journal of Molecular Liquids ; Volume 260 , 15 June , 2018 , Pages 423-435 ; 01677322 (ISSN) Safdari, F ; Shamkhali, A. N ; Tafazzoli, M ; Parsafar, G ; Sharif University of Technology
    Elsevier B.V  2018
    In this study, adsorption of important pollutant cations on the surface of graphitic carbon nitride (g-C3N4) was investigated by density functional theory. The calculations indicated that N6 cavity surrounded by triazine units is the most probable adsorption site on this surface. The structural optimizations also predicted a planar surface for Cr3+, and Ni2+/g-C3N4 systems while the structure of the surface for other systems indicated a considerable distortion with strong dependency on the cation size. Also, g-C3N4 surface exhibited the high adsorption energies for Cr3+, As3+, and Sb3+ ions in the gas phase. However, formation energies of the metal-aquo complexes of these cations indicated... 

    Role of herzberg-teller vibronic coupling in surface-enhanced resonance raman spectra of 4,4′-diaminotolane with nearly close molecular and charge-transfer transitions

    , Article Journal of Physical Chemistry C ; Volume 125, Issue 31 , 2021 , Pages 17202-17211 ; 19327447 (ISSN) Jamshidi, Z ; Ashtari Jafari, S ; Smirnov, A ; Solovyeva, E. V ; Sharif University of Technology
    American Chemical Society  2021
    We have investigated the surface-enhanced resonance Raman spectroscopy (SERRS) for 4,4′-diaminotolane absorbed on silver experimentally and theoretically. Experimental observation shows greatly enhanced bg symmetric modes ν26 and ν27, which are silent in normal Raman spectroscopy and SERS on gold. The dependence of the surface-enhanced Raman spectroscopy (SERS) spectra on five excitation lines has also been registered and classified for single bands into three profiles referring to the different contributions of resonant transitions. Theoretical calculations based on the time-dependent path integral formalism by including the Herzberg-Teller correction reproduce the experimental spectra with... 

    A study on the mechanism of electrodeposition of Ni/SiC composite coatings using impedance technique

    , Article ECS Transactions ; Volume 41, Issue 44 , 2012 , Pages 47-57 ; 19385862 (ISSN) ; 9781607683452 (ISBN) Sohrabi, A ; Dolati, A ; Electrodeposition; Sensor ; Sharif University of Technology
    Ni/SiC nanocomposite coatings were electrodeposited using Watts type bath and different SiC particle size. The electrodeposition behavior of Ni/SiC nanoelectrocomposites was studied using electrochemical techniques such as impedance spectroscopy (EIS) and voltammetry. In this study it was shown that SiC particles modify the EIS diagram and voltammograms as well as surface morphology of electrodeposited layers. Experimental results showed that SiC particles not only affect the formation of intermediate species and decrease charge transfer resistance but also increase the nucleation sites for nickel electrodeposition and thus affect the microstructure of electrodeposited Ni/SiC nanocomposites.... 

    Molecular engineering of bithiazole-based organic dyes with different electron-rich linkers toward highly efficient dye-sensitized solar cells

    , Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 349 , 2017 , Pages 171-182 ; 10106030 (ISSN) Hosseinzadeh, E ; Hadipour, N. L ; Parsafar, G ; Sharif University of Technology
    A series of bithiazole-based dye sensitizers have been designed by employing various electron-rich moieties as π-spacer, which are based on the reported experimentally synthesized dye T-BT, to shed a light on the impact of both the nature and position of electron-rich moiety on the efficiency of dyes in DSSCs. To evaluate the efficiency of these dyes, various key parameters associated with overall conversion efficiency (η), including electronic and optical properties of free dyes are calculated, based on the computational methods. Besides, the dye/TiO2 structures have been taken into account to investigate the interfacial features of the dye sensitizers adsorbed on TiO2 semiconductor and... 

    Not completely innocent: how argon binding perturbs cationic copper clusters

    , Article Journal of Physical Chemistry A ; Volume 124, Issue 43 , 2020 , Pages 9004-9010 Jamshidi, Z ; Lushchikova, O. V ; Bakker, J. M ; Visscher, L ; Sharif University of Technology
    American Chemical Society  2020
    Argon is often considered as an innocent probe that can be attached and detached to study the structure of a particular species without perturbing the species too much. We have investigated whether this assumption also holds for small copper cationic clusters and demonstrated that small but significant charge transfer from argon to metal changes the remaining binding positions, leading in general, to weaker binding of other argon atoms. The exception is binding to just one copper ion, where the binding of the first argon facilitates the binding of the second. © 2020 American Chemical Society  

    Synthesis, characterization and fluorescence spectra of mononuclear Zn(II), Cd(II) and Hg(II) complexes with 1,10-phenanthroline-5,6-dione ligand

    , Article Journal of Coordination Chemistry ; Volume 60, Issue 3 , 2007 , Pages 347-353 ; 00958972 (ISSN) Boghaei, D. M ; Behzadian Asl, F ; Sharif University of Technology
    The mononuclear complexes of Zn(II), Cd(II) and Hg(II), [Zn(phen-dione)Cl2], [Cd(phen-dione)Cl2] and [Hg(phen-dione)Cl2], where phen-dione = 1,10-phenanthroline-5,6-dione, have been synthesized and characterized by elemental analysis and IR, 1H NMR and electronic absorption spectroscopies. The ν(C=O) of coordinated phen-dione ligands in these complexes shows that the phen-dione is not coordinated to metal ion from its C=O sites. Electronic spectra of the complexes show two absorption bands for intraligand transitions. These absorption bands show dependence on the dielectric constant of solvents. These complexes exhibit an intense fluorescence band around 545 nm in DMSO when the excitation... 

    TiO2 surface nanostructuring for improved dye loading and light scattering in double-layered screen-printed dye-sensitized solar cells

    , Article Journal of Applied Electrochemistry ; Volume 45, Issue 8 , 2015 , Pages 831-838 ; 0021891X (ISSN) Jalali, M ; Moakhar, R. S ; Kushwaha, A ; Goh, G. K. L ; Sadrnezhaad, S. K ; Riahi Noori, N ; Sharif University of Technology
    Kluwer Academic Publishers  2015
    Abstract: Surface-nanostructured TiO2 nanorods were synthesized hydrothermally at 180 °C. Such nanorods have ‘crack-like’ surfaces that resemble burnt charcoal. Compared to nanorods with relatively smoother surfaces, the charcoal-like nanorods have higher-specific surface areas. By using the nanorods as a light-scattering layer in double-layered dye-sensitized solar cells, the cells based on the charcoal-like nanorods have 20 % higher dye loading and also higher diffuse reflectance compared with cells utilizing ‘smooth’ nanorods. The efficiency of a screen-printed double-layer dye-sensitized solar cell based on the charcoal-like nanorods is higher at 7.29 %. Electrochemical... 

    Efficient nanostructured biophotovoltaic cell based on bacteriorhodopsin as biophotosensitizer

    , Article ACS Sustainable Chemistry and Engineering ; Volume 3, Issue 5 , March , 2015 , Pages 809-813 ; 21680485 (ISSN) Mohammadpour, R ; Janfaza, S ; Sharif University of Technology
    American Chemical Society  2015
    Here, we report on utilizing a photoactive protein, bacteriorhodopsin (bR), as a light harvester in combination with TiO2 nanoparticles in biosensitized solar cell application. Experiments have been conducted to investigate the capability of surface adsorption of bR on nanoparticular TiO2photoanodes. Different pretreatment processes have been done to modify the interface of TiO2 nanoparticles and bR as a biophotosensitizer. Our results indicate the feasibility of efficient immobilization and photoinduced charge transfer of bR to the nanostructured TiO2 photoelectrode. Under illumination of simulated AM1.5 sunlight, the solar-light-to-electricity... 

    Electrochemical determination of CdS band edges and semiconducting parameters

    , Article Bulletin of the Chemical Society of Japan ; Volume 88, Issue 6 , February , 2015 , Pages 814-820 ; 00092673 (ISSN) Miandari, S ; Jafarian, M ; Mahjani, M. G ; Gobal, F ; Heidaripour, A ; Sharif University of Technology
    Chemical Society of Japan  2015
    Cadmium sulfide (CdS) thin film was electrodeposited on indium tin oxide (ITO) by chronoamperometry. The SEM images showed that hexagonal sheets of CdS deposited on the ITO surface. The X-ray diffraction (XRD) analysis confirmed this structure for CdS crystals and the average of crystalline size and the lattice constant parameters are approximately 39.54 and a = 0.4136, c = 0.6696 nm respectively. Photo-electrochemical investigations were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques. CdS band edges and density of states (DOS) were determined by CV technique. The band gap energy (Ebg) was measured... 

    One-step fabrication of electrochemically reduced graphene oxide/nickel oxide composite for binder-free supercapacitors

    , Article International Journal of Hydrogen Energy ; Volume 41, Issue 39 , 2016 , Pages 17496-17505 ; 03603199 (ISSN) Shahrokhian, S ; Mohammadi, R ; Asadian, E ; Sharif University of Technology
    Elsevier Ltd  2016
    A three-dimensional (3D) graphene/Nickel oxide (ERGO/NiO) composite electrode have been fabricated directly on a Nickel foam substrate via a one-step electrochemical co-deposition in an aqueous solution containing Nickel nitrate and GO. By using this simple and one-step electrochemical deposition, it is possible to produce binder-free composite electrodes with improved electrochemical properties using a low-cost, facile and scalable technique. It is observed from FE-SEM images that graphene oxide sheets affect the electrodeposition of nickel oxide. The optimized ErGO/NiO electrode developed in this work exhibits high charge storage capacity with a specific capacitance of 1715.5 F g−1 at... 

    In-situ electrochemical exfoliation of Highly Oriented Pyrolytic Graphite as a new substrate for electrodeposition of flower like nickel hydroxide: Application as a new high-performance supercapacitor

    , Article Electrochimica Acta ; Volume 206 , 2016 , Pages 317-327 ; 00134686 (ISSN) Shahrokhian, S ; Mohammadi, R ; Amini, M. K ; Sharif University of Technology
    Elsevier Ltd  2016
    Demand for more efficient energy storage devices stimulates efforts to search and develop new materials and composites with promising properties. In this regard, composite materials, including carbonaceous materials and metal oxides have attracted a great attention due to better electrochemical performance as compared to their single material analogues. For the first time, herein, we report a new and simple procedure for preparing porous highly oriented pyrolytic graphite/nickel hydroxide composite (P-HOPG/Ni(OH)2) via a fast and simple two-step electrochemical method including potentiostatic routes. In the first step, a low anodic potential (2 V) was applied to pristine HOPG in 0.5 M H2SO4... 

    Structural, microstructural and electrochemical studies of TiO2-Ag double layer coated NCM cathode for lithium-ion batteries

    , Article Materials Research Express ; Volume 6, Issue 8 , 2019 ; 20531591 (ISSN) Sharifi Rad, A ; Ghorbanzadeh, M ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Lithium ion batteries as one of the most important energy storage equipments, have several challenges including capacity drop as number of cycles increases. Cathode particle coating is an effective approach in improvement of electrochemical performance of the batteries. In this study, TiO2-Ag coating was used to improve NCM cathode performance. The microstructure and crystal structure properties of coated NCMs were evaluated by the FE-SEM and XRD. Electrochemical behavior of the batteries was investigated by cycling performance analysis and EIS. TiO2 coating was deposited as a uniform layer and Ag coating was precipitated as dispersed nanoparticles. The results shows that using of TiO2-Ag... 

    Towards developing efficient metalloporphyrin-based hybrid photocatalysts for CO2reduction; an: ab initio study

    , Article Physical Chemistry Chemical Physics ; Volume 22, Issue 40 , 2020 , Pages 23128-23140 Ostovan, A ; Papior, N ; Zahedi, M ; Moshfegh, A. Z ; Sharif University of Technology
    Royal Society of Chemistry  2020
    A series of thiophene-based donor-acceptor-donor (D-A-D) oligomer substituted metalloporphyrins (MPors) with different 3d central metal-ions (M = Co, Ni, Cu, and Zn) were systematically investigated to screen efficient hybrid photocatalysts for CO2 reduction based on density functional theory (DFT) and time-dependent DFT simulations. Compared with base MPors, the newly designed hybrid photocatalysts have a lower bandgap energy, stronger and broader absorption spectra, and enhanced intermolecular charge transfer, exciton lifetime, and light-harvesting efficiency. Then, the introduction of D-A-D electron donor (ED) groups into the meso-positions of MPors is a promising method for the... 

    Charge transfer in YBCO under pressure with bond valence sum approach

    , Article Journal of Superconductivity and Novel Magnetism ; Volume 18, Issue 2 , 2005 , Pages 299-307 ; 15571939 (ISSN) Mohammadizadeh, M. R ; Akhavan, M ; Sharif University of Technology
    The bond valence sum method has been developed to high pressures considering B0(p) for calculating the valences of atoms. This approach has the advantages of finding a universal B0(P) for all the atoms -at least in YBCO, ability to evaluate the valency of each atom, and charge neutrality requirement of the unit cell. As a result, a new structural refinement has led to a more exact structural detail. The position of apical oxygen is found to be specially crucial for hole distribution between the superconducting CuO2 planes and Cu-O charge reservoir chains. Under pressure, the hole concentration in CuO2 planes increases, but in the Cu-O chains decreases, consistent with the pressure induced... 

    Comparative Studies on Adduct Compounds of Schiff-Base Donors and Some Organic and Inorganic Acceptors

    , M.Sc. Thesis Sharif University of Technology Hendinejad, Niloofar (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    The charge transfer interaction of two Schiff-bases Bis- (2-thiophene methylene)-1,4- Benzene Di amine and Bis (2-thiophene methylene)-1,3- Benzene Di amine as donors with iodine and tetracyano ethylene as Electron acceptors have been studied spectrophotometrically. The formation constants and extinction coefficients of charge transfer complexes have been determined by graphical as well as iterative methods. From measurements at different temperatures the thermodynamic functions of the charge transfer complex formation have been studied. The temperature dependence of the K can be used for the determination of the thermodynamic reaction quantities (ΔG˚, ΔS˚, ΔH˚) for linear regression fits... 

    High pressure effects in YBCO and YSCO

    , Article Physica Status Solidi C: Conferences ; Volume 1, Issue 7 , 2004 , Pages 1859-1862 ; 16101634 (ISSN) Khosroabadi, H ; Mossalla, B ; Akhavan, M ; Sharif University of Technology
    Electronic structure calculations for two isofamilies, YBa 2Cu3O7 (YBCO) and YSr2Cu 3O7 (YSCO) high Tc cuprates, have been done for ambient and high pressures (-15 GPa

    Ba@Pr or Pr@Ba in R123 HTSC - To be or not to be SC

    , Article Physica Status Solidi (B) Basic Research ; Volume 241, Issue 6 , 2004 , Pages 1242-1250 ; 03701972 (ISSN) Akhavan, M ; Sharif University of Technology
    In spite of the vast amount of experimental and theoretical knowledge accumulated in HTSC, the nature of the interaction driving charge carriers to form Cooper pairs below Tc is still unknown. To elucidate the controversial insulating/SC Pr123, the substitution of Pr at Ba site (Pr@Ba) with Ba at Pr site (Ba@Pr) in R123 is compared and reviewed. This might shed some light on the microscopic origin of HTSC. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim  

    Controlled engineering of WS2 nanosheets-CdS nanoparticle heterojunction with enhanced photoelectrochemical activity

    , Article Solar Energy Materials and Solar Cells ; Volume 141 , 2015 , Pages 260-269 ; 09270248 (ISSN) Zirak, M ; Zhao, M ; Moradlou, O ; Samadi, M ; Sarikhani, N ; Wang, Q ; Zhang, H. L ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier  2015
    Abstract We report the well-controlled preparation of WS2 nanosheets-CdS nanoparticle heterojunction for photoelectrochemical (PEC) water splitting application. The WS2 nanosheets with an average thickness of ~5 nm and lateral dimensions of ~200 nm were synthesized via liquid phase exfoliation of bulk WS2 in water/ethanol solution, followed by deposition onto ITO substrate via electrophoretic method. CdS nanoparticles were grown via facile successive ion layer absorption and reaction (SILAR) method. Using these two well-controlled methods, CdS/WS2/ITO and WS2/CdS/ITO systems were fabricated. The loading of WS2 nanosheets was... 

    Carbon quantum dots modified anatase/rutile TiO2 photoanode with dramatically enhanced photoelectrochemical performance

    , Article Applied Catalysis B: Environmental ; Volume 269 , 2020 Zhou, T ; Chen, S ; Li, L ; Wang, J ; Zhang, Y ; Li, J ; Bai, J ; Xia, L ; Xu, Q ; Rahim, M ; Zhou, B ; Sharif University of Technology
    Elsevier B.V  2020
    TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and...