O. Akhavan

Sharif University of Technology, Teheran, Tehrān, Iran

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Publications (130)467.25 Total impact

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    ABSTRACT: Hollow microblocks of [Zn(anic)2], as a novel coordination compound, were synthesized using 2-aminonicotinic acid (Hanic) and zinc (II) nitrate tetrahydrate. The chemical composition of the zinc complex, ZnC12H10N4O4, was determined by Fourier transform infrared (FTIR) spectroscopy and elemental analysis. The synthesized zinc complex was used as a precursor to produce ZnO nanostructures by calcination at 550 °C for 4 h. Morphological studies by scanning electron microscopy and transmission electron microscopy revealed the formation of porous microbricks of ZnO nanoparticles. N2 adsorption-desorption analysis showed that the obtained ZnO microbricks possess a mesoporous structure with a surface area of 8.13 m2/g and a pore size of 22.6 nm. The X-ray diffraction pattern of the final product proved the formation of a pure ZnO composition with a hexagonal structure. Moreover, FTIR analyses showed that the 2-aminonicotinic acid ligand peaks were absent after the calcination step. Diffuse reflectance spectroscopy was used to determine the band gap energy of the produced ZnO and it was about 3.19 eV. To investigate the photocatalytic activity of the porous ZnO nanostructure, a series of photocatalytic tests were carried out to remove Congo red, as a representative toxic azo dye, from aqueous solution. The results show that the product can be used as an efficient photocatalyst for waste water treatment with high degradation efficiency.
    Chinese Journal of Catalysis 12/2015; 36(5):742-749. DOI:10.1016/S1872-2067(14)60305-3 · 1.55 Impact Factor
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    R. Azimirad, S. Safa, O. Akhavan
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    R. Azimirad, S. Safa, O. Akhavan
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    ABSTRACT: Various morphologies of monoclinic CuO powders were synthesized by hydrothermal treatment of copper nitrate, copper acetate or copper sulfate. The synthesized samples were characterized by scanning electron microscopy, X-ray di�ractometry, the Fourier transform infrared spectroscopy, and di�use re ectance spectrophotometry. Antibacterial activity of the samples was studied against Escherichia coli bacteria in dark and under visible light irradiation. Although the di�erent precursors yielded the same band gap energies (�1.6 eV) for the synthesized CuO samples, they resulted in various morphologies (hierarchy of stabilized micro/nanostructures), speci c surface areas, concentrations of OH-surface groups, and visible light photocatalytic performances. The CuO nanorods synthesized from nitrate hydrothermal bath not only exhibited a considerable e�ective surface area, but also showed the highest concentration of absorbed OH-groups and subsequently, the strongest (photo)catalytic antibacterial properties (�37 and 94% inactivation of the bacteria in dark and under visible light irradiation, respectively).
    Acta Physica Polonica Series a 06/2015; 127(6):1727. DOI:10.12693/APhysPolA.127.1727 · 0.60 Impact Factor
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    ABSTRACT: Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400–800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50–90 nm and crystalline phase of WO3) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K2W6O19 crystalline phase were formed on the foils. The WO3 nanorods showed a strong antibacterial property under visible light irradiation, corresponding to >92% bacterial inactivation within 24 h irradiation at room temperature, while the K2W6O19 microrods formed at 800 °C could inactivate only ∼45% of the bacteria at the same conditions.
    Applied Surface Science 05/2015; 338. DOI:10.1016/j.apsusc.2015.01.217 · 2.54 Impact Factor
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    ABSTRACT: Superparamagnetic iron oxide (SPIO) nanomaterials are widely used as magnetic resonance imaging (MRI) contrast agents (CAs). These CAs significantly shorten transverse relaxation time (T2) and so decrease the intensity of the T2-weighted MRI (negative contrast imaging). However, the partial-volume effect is known as one of the problems in negative contrast MRI. In this work, SPIO nanoparticles were modified by dextran and graphene oxide (GO) nanosheets to achieve a positive contrast MRI with high intensity. This modification resulted in shortening the longitudinal relaxation time (T1) of the SPIO nanoparticles (in addition to the T2 shortening). Using FLASH pulse sequence, T1-weighted positive contrast MRI of Wistar rats revealed that the SPIO/dextran-functionalized GO (SPIO-Dex-FGO) significantly enhanced the contrast to noise ratio (CNR) of the positive contrast MRI as compared to the common clinical positive CA, i.e., Magnevsit®. In fact, based on the CNR calculations for in-vivo positive contrast images it was found that the SPIO-Dex-FGO could provide the same CNR as Magnevsit® at concentrations two orders of magnitudes lower than the concentrations used for Magnevist®. Therefore, SPIO-Dex-FGO can propose as a promising substitution for the current CAs such as Magnevsit® in T1-weighted positive contrast MRI, at lower and safer concentrations.
    RSC Advances 05/2015; 5(59). DOI:10.1039/C5RA03331D · 3.71 Impact Factor
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    ABSTRACT: H2-rich water as a green antioxidant was applied for deoxygenation of graphene oxide (GO) suspensions. The ability of H2-rich water for deoxygenation of GO sheets was found comparable to the ability of hydrazine (as a standard and powerful reductant), using X-ray photoelectron spectroscopy. In fact, the O/C ratio of GO sheets could be reduced from 0.51 to 0.21 and 0.16 by H2-rich water and hydrazine, respectively. More importantly, while C–N bond formation is one of the side effects of GO reduction by hydrazine, no chemical C–N bond was found on the H2-water-reduced GO (rGO) sheets. This also resulted in a better restoration of the graphitic structure of the H2-water-rGO, as confirmed by Raman spectroscopy. Although H2-rich water exhibited slightly lower deoxygenation efficiency than hydrazine, the absence of any C–N bond on the H2-water-rGO resulted in an excellent electrical conductivity (corresponding to the sharp reduction in the electrical sheet resistance (Rs) of the GO sheets from ∼6.3 × 1010 to 7.2 × 105 Ω/sq) which is comparable with the typical conductivity of hydrazine-rGO sheets (here, with Rs value of ∼4.4 × 105 Ω/sq). These results suggest application of H2-rich water as an effective substitute for hydrazine in environment-friendly and mass production of rGO sheets.
    International Journal of Hydrogen Energy 05/2015; 40(16). DOI:10.1016/j.ijhydene.2015.02.106 · 2.93 Impact Factor
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    ABSTRACT: Reduced graphene oxide nanomeshes (rGONMs), as p-type semiconductors with band-gap energy of ∼1 eV, were developed and applied in near infrared (NIR) laser stimulation of human neural stem cells (hNSCs) into neurons. The biocompatibility of the rGONMs in growth of hNSCs was found similar to that of the graphene oxide (GO) sheets. Proliferation of the hNSCs on the GONMs was assigned to the excess oxygen functional groups formed on edge defects of the GONMs, resulting in superhydrophilicity of the surface. Under NIR laser stimulation, the graphene layers (especially the rGONMs) exhibited significant cell differentiations, including more elongations of the cells and higher differentiation of neurons than glia. The higher hNSC differentiation on the rGONM than the reduced GO (rGO) was assigned to the stimulation effects of the low-energy photoexcited electrons injected from the rGONM semiconductors into the cells, while the high-energy photoelectrons of the rGO (as a zero band-gap semiconductor) could suppress the cell proliferation and/or even cause cell damages. Using conventional heating of the culture media up to ∼43 °C (the temperature typically reached under the laser irradiation), no significant differentiation was observed in dark. This further confirmed the role of photoelectrons in the hNSC differentiation.
    Colloids and surfaces B: Biointerfaces 02/2015; 126. DOI:10.1016/j.colsurfb.2014.12.027 · 4.29 Impact Factor
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    ABSTRACT: The hard corona, the protein shell that is strongly attached to the surface of nano-objects in biological fluids, is recognized as the first layer that interacts with biological objects (e.g., cells and tissues). The decoration of the hard corona (i.e., the type, amount, and conformation of the attached proteins) can define the biological fate of the nanomaterial. Recent developments have revealed that corona decoration strongly depends on the type of disease in human patients from which the plasma is obtained as a protein source for corona formation (referred to as the ‘personalized protein corona’). In this study, we demonstrate that graphene oxide (GO) sheets can trigger different biological responses in the presence of coronas obtained from various types of diseases. GO sheets were incubated with plasma from human subjects with different diseases/conditions, including hypofibrinogenemia, blood cancer, thalassemia major, thalassemia minor, rheumatism, fauvism, hypercholesterolemia, diabetes, and pregnancy. Identical sheets coated with varying protein corona decorations exhibited significantly different cellular toxicity, apoptosis, and uptake, reactive oxygen species production, lipid peroxidation and nitrogen oxide levels. The results of this report will help researchers design efficient and safe, patient-specific nano biomaterials in a disease type-specific manner for clinical and biological applications.
    Nanoscale 01/2015; 7(19). DOI:10.1039/C5NR00520E · 6.74 Impact Factor
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    ABSTRACT: Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ~1min for 2mgmL(-1) of the nanoparticles in ethanol) by applying an external magnetic field (~1T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of (60)Co source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100μgmL(-1), in the absence of gamma irradiation. The gamma irradiation alone (2Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100μgmL(-1) ZnFe2O4 nanoparticles resulted in ~53% inactivation of the cells (~17 times higher than the inactivation that occurred under gamma irradiation alone) after 24h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe2O4 nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy. Copyright © 2014 Elsevier B.V. All rights reserved.
    Materials Science and Engineering C 01/2015; 46:394-9. DOI:10.1016/j.msec.2014.10.062 · 2.74 Impact Factor
  • O. Akhavan
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    ABSTRACT: Bacteriorhodopsin (bR) molecules were utilized as light-driven proton pumps for green as well as effective reduction of single-layer graphene oxide (GO) sheets. The bR molecules and graphene sheets were separated from each other in an aqueous environment by using a polytetrafluoroethylene membrane filter, in order to prevent their direct interactions (including attachment of the bR molecules onto the GO). Although reduction of GO using hydrazine or bR showed similar deoxygenation levels (based on X-ray photoelectron spectroscopy), the former resulted in formation of CN bonds which can substantially decrease the electrical conductivity of the reduced sheets. The electrical characteristics of the single-layer graphene sheets were studied by recording current–voltage curves of the sheets located between two Au electrodes on a SiO2 (300 nm)/Si (100) substrate. The electrical conductivity of the bR-reduced graphene oxide (rGO) sheets was found about one order of magnitude better than that of hydrazine-rGO sheets. The excellent electrical conductivity of the bR-rGO sheets (with sheet resistance of ∼7.1 × 104 Ω/sq) was assigned to the effective deoxygenation (without formation of any CN bonds) and better restoration of the graphitic structure of the GO sheets, using the protons pumped by the bR molecules.
    Carbon 01/2015; 81. DOI:10.1016/j.carbon.2014.09.044 · 6.16 Impact Factor
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    ABSTRACT: Graphene nanoplatelets with lateral dimensions of 50–200 nm and thicknesses <2 nm were utilized for the extraction of nucleic acids (NAs) from eukaryotic and prokaryotic cells. The graphene nanoplatelets (both chemically exfoliated graphene oxide nanoplatelets and hydrazine-reduced graphene oxide nanoplatelets) successfully extracted plasmid DNA (pDNA) from Escherichia coli bacteria, comparable to a conventional phenol–chloroform (PC) method. Furthermore, it was found that the yield of graphene nanoplatelets in genomic DNA (gDNA) and RNA extractions from embryonic stem cells (ESCs) was also comparable to the yield of the conventional methods. The effects of the graphene nanoplatelets on restriction enzyme digestion of the pDNA and gene amplification of all the extracted NAs (including pDNA, gDNA and RNA) were also investigated in order to confirm the quality of the extractions. These results not only demonstrated an easy gene extraction capability of graphene nanoplatelets with a high gene amplification, but also provide an easy, fast, inexpensive and biocompatible DNA/RNA extraction method.
    RSC Advances 11/2014; 4(105). DOI:10.1039/C4RA11458B · 3.71 Impact Factor
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    ABSTRACT: Mg2+-charged spongy graphene electrodes (SGEs) were fabricated by using electrophoretic deposition of chemically exfoliated graphene oxide sheets on graphite rods. The SGEs were able to present two distinguishable signals (originated from electrochemical oxidation of guanine) in differential pulse voltammetry (DPV) of leukemia and normal blood cells, in contrast to glassy carbon electrodes giving only one overlapped peak. Hence, the SGEs were applied in fast (60 min) and ultra sensitive detection of leukemia (single abnormal cells in similar to 10(9) normal cells) in a blood serum. The sensitivity obtained by the SGEs was three orders of magnitude better than that of the best available and current technologies (e.g., specific mutations by polymerase chain reaction with detection limit of one abnormal cell in similar to 10(6) normal cells) which not only are expensive, but also require several days for incubation. Significant variations in DPV signals of the SGEs after the first electrochemical cycle indicated that the best performance of the SGEs can be achieved only at the first cycle. The linear dynamic detection behavior of the SGEs was investigated in wide concentration range of 1.0 x 10(5)-0.1 cell/mL. The lower detection limit was estimated similar to 0.02 celVmL, based on the current resolution obtained by the SGEs.
    Carbon 11/2014; 79:654-663. DOI:10.1016/j.carbon.2014.08.058 · 6.16 Impact Factor
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    ABSTRACT: Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO NVVs into the GO sheets, during photocatalytic reduction of the sheets. The obtained rGO/ZnO composites were applied in visible light photoinactivation of Escherichia coli bacteria. The ZnO NWs could inactivate only similar to 58% of the bacteria, while both drop-casting and EPD-prepared GO/ZnO composites exhibited strong antibacterial activities (especially the EPD sample with similar to 99.5% photoinactivation), under visible light irradiation for I h. In fact, the visible light photocatalytic activity of the EPD-prepared GO/ZnO NW composite was found similar to 1.9 and 6.2 folds of the activity of the GO/ZnO composite prepared by drop-casting method and the bare ZnO NWs.
    Journal of Alloys and Compounds 11/2014; 612:380-385. DOI:10.1016/j.jallcom.2014.05.195 · 2.73 Impact Factor
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    ABSTRACT: tGraphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walledcarbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serumor human plasma serum indicated that the GONRs were functionalized substantially by the albuminoriginated from the two different protein sources. Then, concentration-dependent cytotoxicity of theprotein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concen-trations ≤50 �g/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), theconcentration of 100 �g/mL exhibited significant cytotoxicity including prevention of cell proliferationand induction of cell apoptosis. These results can provide more in-depth understanding about cytotoxiceffects of graphene nanostructures which can be functionalized by the proteins of media.
    Applied Surface Science 11/2014; DOI:10.1016/j.apsusc.2014.09.155 · 2.54 Impact Factor
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    ABSTRACT: Graphene oxide nanoplatelets (GONPs) with extremely sharp edges (lateral dimensions ~20–200 nm and thicknesses <2 nm) were applied in extraction of the overexpressed guanine synthesized in cytoplasm of leukemia cells. The blood serums containing the extracted guanine were used in differential pulse voltammetry (DPV) supplied by reduced graphene oxide nanowall (rGONW) electrodes to develop fast and ultra sensitive electrochemical detections of leukemia cells at leukemia fractions (LFs) of ~10-11 (as the lower detection limit). Stability of the DPV signals obtained through oxidation of the extracted guanine on the rGONWs was studied after 20 cycles. Without the guanine extraction, the DPV peaks relating to guanine oxidation of normal and abnormal cells were overlapped at LFs <10-9, and consequently, the performance of alone rGONWs were limited at this level. As a benchmark, the DPV using glassy carbon electrodes was able to detect only LFs ~10-2. The ultra sensitivity obtained by this combination method (guanine extraction by GONPs and then guanine oxidation by rGONWs) is five orders of magnitude better than the sensitivity of the best current technologies (e.g., specific mutations by polymerase chain reaction) which not only are expensive, but also require few days for diagnosis.
    Nanoscale 10/2014; DOI:10.1039/C4NR04589K · 6.74 Impact Factor
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    ABSTRACT: Graphene oxide (GO) sheets functionalized by aminopropylsilyl groups (8.0 wt.%) were labeled by 198,199Au nanoparticle radioisotopes (obtained through reduction of HAuCl4 in sodium citrate solution followed by thermal neutron irradiation) for fast in vivo targeting and SPECT imaging (high purity germanium-spectrometry) of tumors. Using instant thin layer chromatography method, the physicochemical properties of the amino-functionalized GO sheets labeled by 198,199Au NPs (198,199Au@AF-GO) were found to be highly stable enough in organic phases, e.g. a human serum, to be reliably used in bioapplications. In vivo biodistribution of the 198,199Au@AF-GO composite was investigated in rats bearing fibrosarcoma tumor after various post-injection periods of time. The 198,199Au@AF-GO nanostructure exhibited a rapid as well as high tumor uptake (with uptake ratio of tumor to muscle of 167 after 4 h intravenous injection) that resulted in an efficient tumor targeting/imaging. Meantime, the low lipophilicity of the 198,199Au@AF-GO caused to its fast excretion (~ 24 h) throughout the body by the kidneys (as also confirmed by the urinary tract). Because of the short half-life of 198,199Au radioisotopes, the 198,199Au@AF-GO with an excellent tumor targeting/imaging and fast washing out from the body can be suggested as one of the most effective and promising nanomaterials in nanotechnology-based cancer diagnosis and therapy.
    Materials Science and Engineering C 09/2014; 45. DOI:10.1016/j.msec.2014.09.019 · 2.74 Impact Factor
  • Omid Akhavan, Elham Ghaderi
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    ABSTRACT: An effective and self-organized differentiation of human neural stem cells (hNSCs) into neurons was developed by pulsed laser stimulation of the cells on graphene films (prepared by drop-casting GO suspension onto quartz substrates). The effects of graphene oxide (GO) and hydrazine-reduced graphene oxide (rGO) sheets on proliferation of hNSCs were examined. The higher proliferation of the cells on the GO was assigned to its better hydrophilicity. On the other hand, the rGO sheets with significantly better electrical conductivity than GO exhibited more differentiation of the cells into neurons. The pulsed laser stimulation not only resulted in accelerated differentiation of the hNSCs into neurons (rather than glia), but also caused self-organization of a radial neuronal network on surface of the rGO sheets, due to a radial stress induced by the surface thermal gradient originated from the center of the laser spot. The higher thermal conductivity of the rGO sheets (as compared to the GO sheets and the quartz substrate) provided better outwards heat flow from the center of laser spot, and consequently, prevented an extra local heating at the position of laser spot. These results can excite more investigations on the advantages of graphene in self-organized differentiation of hNSCs, using pulsed laser stimulation.
    06/2014; 2(34). DOI:10.1039/C4TB00668B
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    ABSTRACT: A magneto-photothermal therapy for cancer (in vitro photothermal therapy of prostate cancer cells and in vivo photothermal therapy of human glioblastoma tumors in the presence of an external magnetic field) was developed using superparamagnetic zinc ferrite spinel (ZnFe2O4)–reduced graphene oxide (rGO) nanostructures (with various graphene contents). In vitro application of a low concentration (10 μg mL−1) of the ZnFe2O4–rGO (20 wt%) nanostructures under a short time period (1 min) of near-infrared (NIR) irradiation (with a laser power of 7.5 W cm−2) resulted in an excellent destruction of the prostate cancer cells, in the presence of a magnetic field (1 Tesla) used for localizing the nanomaterials at the laser spot. However, in the absence of a magnetic field, ZnFe2O4–rGO and also rGO alone (10 μg mL−1) resulted in only 50% cell destruction at the most in the short photothermal therapy and also in a typical radiotherapy (2 min gamma irradiation with a dose of 2 Gy). The minimum concentrations required for the successful application of the nanostructures in the photothermal and radiotherapeutic methods were found to be 100 and 1000 μg mL−1, while in the proposed magneto-photothermal therapy it was only 10 μg mL−1. The in vivo feasibility of this method was also examined on mice bearing glioblastoma tumors. Furthermore, the localization of the magnetic nanomaterials injected into the tumors was studied in the presence and absence of an external magnetic field. These results will stimulate more applications of magnetic graphene-containing composites in highly efficient photothermal therapy.
    05/2014; 2(21). DOI:10.1039/C3TB21834A
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    ABSTRACT: Pd-WO3 nanostructures were incorporated on graphene oxide (GO) and partially reduced graphene oxide (PRGO) sheets using a controlled hydrothermal process to fabricate effective hydrogen gas sensors. Pd-WO3 nanostructures showed ribbon-like morphologies and Pd-WO3/GO presented an irregular nanostructured form, while Pd-WO3/PRGO exhibited a hierarchical nanostructure with a high surface area. Gas sensing properties of thin films of these materials were studied for different hydrogen concentrations (from 20 to 10,000 ppm) at various temperatures (from room temperature to 250 degrees C). Although adding GO in the Pd-WO3, after hydrothermal process could increase the film conductivity, gas sensitivity was reduced to half, due to lower surface area of the irregular morphology in comparison with the ribbon-like morphology. The Pd-WO3/PRGO films showed an optimum sensitivity (similar to 10 folds better than the sensitivity of Pd WO3/GO), and a fast response and recovery time (<1 min) at low temperature of 100 degrees C. Moreover, the Pd-WO3/PRGO-based gas sensor was sensitive to 20 ppm concentration of hydrogen gas at room temperature. The results confirmed the effect of residual oxygen-containing functional groups of PRGO on the growth and morphology of Pd-WO3 as well as gas sensing properties of metal oxide/graphene based hybrid nanostructures. Copyright
    International Journal of Hydrogen Energy 05/2014; 39(15-15):8169-8179. DOI:10.1016/j.ijhydene.2014.03.117 · 2.93 Impact Factor
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    ABSTRACT: Graphene oxide (GO) sheets were synthesized through a modified Hummers' method. Using high resolution transmission electron microscopy the thickness of the GO sheets in a multilayer structure of stacked GO sheets was found ̃0.8 nm. A nanosecond pulsed laser (with wavelength of 532 nm and average power of 0.3 W) was applied for effective and environment friendly reduction of the GO sheets in an ammonia solution (pH ̃9) at room temperature conditions. The deoxygenation of the GO sheets by the pulsed laser reduction method was confirmed by using UV─visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis. Based on XPS analysis, the O/C ratio of the GO sheets decreased from 49% to 21% after 10 min laser irradiation. This reduction efficiency was comparable with the efficiency achieved by hydrazine which yielded the O/C ratio of 15% at 80 °C after 10 min. Using Raman spectroscopy it was found that the pulsed laser reduction method resulted in nearly no aggregation of the reduced GO sheets in the ammonia solution. These results can help to further promotion and application of pulsed lasers in environment friendly reduction of GO.
    Applied Surface Science 04/2014; 301. DOI:10.1016/j.apsusc.2014.02.036 · 2.54 Impact Factor