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  • 51. Bin Abdul Rahim, H. R.
    et al.
    Bin Lokman, M. Q.
    Harun, S. W.
    Hornyak, G. L.
    Sterckx, K.
    Mohammed, W. S.
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Applied light-side coupling with optimized spiral-patterned zinc oxide nanorod coatings for multiple optical channel alcohol vapor sensing2016In: Journal of Nanophotonics, ISSN 1934-2608, Vol. 10, no 3, article id 036009Article in journal (Refereed)
    Abstract [en]

    The width of spiral-patterned zinc oxide (ZnO) nanorod coatings on plastic optical fiber (POF) was optimized theoretically for light-side coupling and found to be 5 mm. Structured ZnO nanorods were grown on large core POFs for the purpose of alcohol vapor sensing. The aim of the spiral patterns was to enhance signal transmission by reduction of the effective ZnO growth area, thereby minimizing light leakage due to backscattering. The sensing mechanism utilized changes in the output signal due to adsorption of methanol, ethanol, and isopropanol vapors. Three spectral bands consisting of red (620 to 750 nm), green (495 to 570 nm), and blue (450 to 495 nm) were applied in measurements. The range of relative intensity modulation (RIM) was determined to be for concentrations between 25 to 300 ppm. Methanol presented the strongest response compared to ethanol and isopropanol in all three spectral channels. With regard to alcohol detection RIM by spectral band, the green channel demonstrated the highest RIM values followed by the blue and red channels, respectively.

  • 52. Boonyanitipong, Prapatsorn
    et al.
    Kositsup, Boonthida
    Kumar, Prabhat
    Baruah, Sunandan
    Dutta, Joydeep
    Asian Institute of Technology (AIT), Bangkok, Thailand.
    Toxicity of ZnO and TiO2 Nanoparticles on Germinating Rice Seed2011In: International Journal of Bioscience, Biochemistry and Bioinformatics, ISSN 2010-3638, Vol. 1, p. 282-285Article in journal (Refereed)
    Abstract [en]

    The present study is aimed at investigating the effects of zinc oxide nanoparticles (nano-ZnO) and titanium dioxide nanoparticles (nano-TiO2) on rice (Oryza sativa L.) roots. Three parameters are examined in this study: seed germination percentage, root length, and number of roots. The results show that there is no reduction in the percent seed germination from both nanoparticles, however nano-ZnO is observed to have detrimental effects on rice roots at early seedling stage. Nano-ZnO is found to stunt roots length and reduce number of roots. Whereas nano-TiO2 has no effect on root length. This study shows that direct exposure to specific types of nanoparticles causes significant phytotoxicity, emphasizes the need for ecologically responsible disposal of wastes containing nanoparticles and also highlights the necessity for further study on the impacts of nanoparticles on agricultural and environmental systems.

  • 53. Bora, T.
    et al.
    Al-Hinai, M. H.
    Al-Hinai, A. T.
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Phase Transformation of Metastable ZnSnO3 Upon Thermal Decomposition by In-Situ Temperature-Dependent Raman Spectroscopy2015In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916Article in journal (Refereed)
    Abstract [en]

    Temperature-dependent in-situ Raman spectroscopy is used to investigate the phase transformation of zinc metastannate (ZnSnO<inf>3</inf>) to zinc orthostannate (Zn<inf>2</inf>SnO<inf>4</inf>) induced upon annealing in the ambient. ZnSnO<inf>3</inf> microcubes (MCs) were synthesized at room temperature using a simple aqueous synthesis process, followed by characterization using electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Annealing of the ZnSnO<inf>3</inf> MCs was carried out up to 1000°C, while recording the Raman spectra in-situ at regular intervals. Phase transformation from metastannate to orthostannate was found to begin around 500°C with an activation energy of ~0.965 eV followed by the recrystallization into the inverse spinel orthostannate phase at ~750°C. Results from this study provide detailed understanding of the phase transformation behavior of perovskite ZnSnO<inf>3</inf> to inverse spinel Zn<inf>2</inf>SnO<inf>4</inf> upon thermal annealing.

  • 54. Bora, T.
    et al.
    Kyaw, H. H.
    Dutta, Joydeep
    Water Research Center, Sultan Qaboos University.
    Plasmon resonance enhanced zinc oxide photoelectrodes for improvement in performance of dye sensitized solar cells2014In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 771, p. 91-101Article in journal (Refereed)
    Abstract [en]

    Nanocomposites of vertically aligned zinc oxide (ZnO) nanorod arrays incorporated with gold (Au) nanoparticles have been used as photoelectrodes to fabricate dye sensitized solar cells (DSSCs). Due to the surface plasmon resonance of the Au nanoparticles, the nanocomposite photoelectrodes demonstrate enhancement in the visible light absorption resulting in ~8% higher photocurrent compared to ZnO photoelectrode based DSSCs fabricated without any Au nanoparticles. In addition to the higher optical absorption due to the gold nanoparticles, a Schottky barrier forms at the ZnO/Au interface preventing the back electron transfer from the conduction band of the semiconductor nanorods to the redox electrolyte providing improvement in the charge separation at the nanocomposite photoelectrode. Upon incorporation of Au nanoparticles, the overall efficiency of the DSSC increased from 2. 41% to 3. 27%. The role of Au nanoparticles on the performance of the DSSCs for varying concentration of the Au nanoparticles as well as the post-growth annealing treatment of the nanocomposite photoelectrode is reported.

  • 55. Bora, T.
    et al.
    Kyaw, H. H.
    Sarkar, S.
    Pal, S. K.
    Dutta, Joydeep
    School of Engineering and Technology, Asian Institute of Technology, Thailand.
    Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process2011In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 2, no 1, p. 681-690Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) nanorods decorated with gold (Au) nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC). The picosecond-resolved, time-correlated single-photon-count (TCSPC) spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE) of 6.49% for small-area (0.1 cm(2)) ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm(2)), similar to 130% enhancement in PCE (from 0.50% to 1.16%) was achieved after incorporation of the Au nanoparticles into the ZnO nanorods.

  • 56. Bora, Tanujjal
    et al.
    Dutta, Joydeep
    Water Research Center, Nanotechnology, Sultan Qaboos University, Oman.
    Applications of nanotechnology in wastewater treatment-A review2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 1, p. 613-626Article in journal (Refereed)
    Abstract [en]

    Water on Earth is a precious and finite resource, which is endlessly recycled in the water cycle. Water, whose physical, chemical, or biological properties have been altered due to the addition of contaminants such as organic/inorganic materials, pathogens, heavy metals or other toxins making it unsafe for the ecosystem, can be termed as wastewater. Various schemes have been adopted by industries across the world to treat wastewater prior to its release to the ecosystem, and several new concepts and technologies are fast replacing the traditional methods. This article briefly reviews the recent advances and application of nanotechnology for wastewater treatment. Nanomaterials typically have high reactivity and a high degree of functionalization, large specific surface area, size-dependent properties etc., which makes them suitable for applications in wastewater treatment and for water purification. In this article, the application of various nanomaterials such as metal nanoparticles, metal oxides, carbon compounds, zeolite, filtration membranes, etc., in the field of wastewater treatment is discussed.

  • 57.
    Bora, Tanujjal
    et al.
    Asian Inst Technol, Sch Engn & Technol, Ind Syst Engn, Nanotechnol, POB 4, Klongluang 12120, Pathumthani, Thailand..
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Plasmonic Photocatalyst Design: Metal-Semiconductor Junction Affecting Photocatalytic Efficiency2019In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 19, no 1, p. 383-388Article in journal (Refereed)
    Abstract [en]

    Silver-zinc oxide nanorods (Ag-ZnO NRs) and gold-zinc oxide nanorods (Au-ZnO NRs) plasmonic photocatalysts were fabricated by the deposition of Ag and Au nanoparticles on ZnO NRs. The photocatalysts were studied with electron microscopy, energy dispersive spectroscopy (EDS), UV-vis optical absorption and photoluminescence spectroscopy. The effect of type of metals on the ZnO surface on its photocatalytic activity under ultra violet (UV) as well as visible light excitation are investigated and their contribution towards enhanced photo-generated charge separation in terms of the type of junction (Ohmic or Schottky) the metal forms with the semiconductor are explained.

  • 58. Bora, Tanujjal
    et al.
    Fallah, H.
    Chaudhari, M.
    Apiwattanadej, T.
    Harun, S. W.
    Mohammed, W. S.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Controlled side coupling of light to cladding mode of ZnO nanorod coated optical fibers and its implications for chemical vapor sensing2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 202, p. 543-550Article in journal (Refereed)
    Abstract [en]

    Controlled light coupling from surrounding to the cladding mode of zinc oxide (ZnO) nanorod coated multimode optical fiber induced by the light scattering properties of the nanorod coating and their applications of sensing are reported here. A dense and highly ordered array of ZnO nanorods is grown on the cladding of silica fibers by using low temperature hydrothermal process and the effect of the hydrothermal growth conditions of the nanorods on the light scattering and coupling to the optical fibers is experimentally investigated. The nanorod length and its number per unit area are found to be most crucial parameters for the optimum side coupling of light into the fibers. Maximum excitation of the cladding mode by side coupling of light is obtained with ZnO nanorods of length similar to 2.2 mu m, demonstrating average coupling efficiency of similar to 2.65%. Upon exposure to different concentrations of various chemical vapors, the nanorod coated fibers demonstrated significant enhancement in the side coupled light intensity, indicating the potential use of these ZnO nanorod coated fibers as simple, low cost and efficient optical sensors. The sensor responses to methanol, ethanol, toluene and benzene vapor were investigated and compared, while the effect of humidity in the sensing environment on the sensor performance was explored as well.

  • 59. Bora, Tanujjal
    et al.
    Kyaw, Htet H
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Zinc oxide–zinc stannate core–shell nanorod arrays for CdS quantum dot sensitized solar cells2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 68, p. 141-145Article in journal (Refereed)
    Abstract [en]

    Nanorod arrays of zinc oxide–zinc stannate core–shell photoelectrodes were prepared by a simple hydrothermal process and cadmium sulfide (CdS) quantum dot sensitized solar cells were fabricated. The photocurrent density of the core–shell photoelectrode was found to improve by ∼2.4 times compared to ZnO nanorod photoelectrodes, due to improved surface area and charge transport in the core–shell photoelectrodes. With a thin layer of ZnS on the CdS quantum dot surface, the core–shell quantum dot sensitized solar cell demonstrated maximum power conversion efficiency of 1.24% under 1 sun illumination (AM1.5).

  • 60. Bora, Tanujjal
    et al.
    Lakshman, Karthik K
    Sarkar, Soumik
    Makhal, Abhinandan
    Sardar, S.
    Pal, S. K.
    Dutta, Joydeep
    School of Engineering and Technology, Asian Institute of Technology, Thailand.
    Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin2013In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 4, no 1, p. 714-725Article in journal (Refereed)
    Abstract [en]

    In recent years, nanotechnology has gained significant interest for applications in the medical field. In this regard, a utilization of the ZnO nanoparticles for the efficient degradation of bilirubin (BR) through photocatalysis was explored. BR is a water insoluble byproduct of the heme catabolism that can cause jaundice when its excretion is impaired. The photocatalytic degradation of BR activated by ZnO nanoparticles through a non-radiative energy transfer pathway can be influenced by the surface defect-states (mainly the oxygen vacancies) of the catalyst nanoparticles. These were modulated by applying a simple annealing in an oxygen-rich atmosphere. The mechanism of the energy transfer process between the ZnO nanoparticles and the BR molecules adsorbed at the surface was studied by using steady-state and picosecond-resolved fluorescence spectroscopy. A correlation of photocatalytic degradation and time-correlated single photon counting studies revealed that the defect-engineered ZnO nanoparticles that were obtained through post-annealing treatments led to an efficient decomposition of BR molecules that was enabled by Forster resonance energy transfer.

  • 61. Bora, Tanujjal
    et al.
    Myint, M T Z
    Al-Harthi, Salim
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Department in Nanotechnology, Water Research Center, Sultan Qaboos University, P. O. Box 17, Al Khoud, Oman.
    Role of surface defects on visible light enabled plasmonic photocatalysis in Au–ZnO nanocatalysts2015In: RSC Advances, ISSN 2046-2069, Vol. 5, no 117, p. 96670-96680Article in journal (Refereed)
    Abstract [en]

    Visible light photocatalytic activity of the plasmonic gold-zinc oxide (Au-ZnO) nanorods (NRs) is investigated with respect to the surface defects of the ZnO NRs, controlled by annealing the NRs in ambient at different temperatures. Understanding the role of surface defects on the charge transfer behaviour across a metal-semiconductor junction is vital for efficient visible light active photocatalysis. Au nanoparticles (NPs) are in situ deposited on the surface of the ZnO NRs having different surface defect densities, demonstrating efficient harvesting of visible light due to the surface plasmon absorption. The surface defects in the ZnO NRs are probed by using photoluminescence (PL) spectroscopy, X-ray photoemission spectroscopy (XPS), and photo-electro-chemical current-voltage measurements to study the photo-generated charge transfer efficiency across the Au-ZnO Schottky interface. The results show that the surface situated oxygen vacancy sites in the ZnO NRs significantly reduce the charge transfer efficiency across the Au-ZnO Schottky interfaces lowering the photocatalytic activity of the system. Reduction in the oxygen vacancy sites through annealing the ZnO NRs resulted in the enhancement of visible light enabled photocatalytic activity of the Au-ZnO plasmonic nanocatalyst, adding vital insight towards the design of efficient plasmonic photocatalysts.

  • 62. Bora, Tanujjal
    et al.
    Sathe, Priyanka
    Laxman, Karthik
    Dobretsov, Sergey
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Defect engineered visible light active ZnO nanorods for photocatalytic treatment of water2017In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 284, p. 11-18Article in journal (Refereed)
    Abstract [en]

    Photocatalytic degradation of organic wastes and microbes in water using solar light is a green technology that requires the design of visible light active photocatalysts. Here we report the fabrication of visible light active zinc oxide nanorods (ZnO NRs), wherein the visible light absorption is enhanced by modulating the surface defects on the NRs. Oxygen vacancies in the NRs as characterized by photoluminescence and X-ray photoelectron spectroscopy are controlled by annealing at different temperatures in the ambient. The role of surface defects on the visible light photocatalytic degradation of an organic dye, industrial waste, bacterial culture and inland brackish water is studied. Results presented here provide a simple strategy to make the wide bandgap ZnO NRs visible light active, enabling their use for the photocatalytic decontamination of water.

  • 63. Bora, Tanujjal
    et al.
    Zoepfl, David
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Importance of Plasmonic Heating on Visible Light Driven Photocatalysis of Gold Nanoparticle Decorated Zinc Oxide Nanorods2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 26913Article in journal (Refereed)
    Abstract [en]

    Herein we explore the role of localized plasmonic heat generated by resonantly excited gold (Au) NPs on visible light driven photocatalysis process. Au NPs are deposited on the surface of vertically aligned zinc oxide nanorods (ZnO NRs). The localized heat generated by Au NPs under 532 nm continuous laser excitation (SPR excitation) was experimentally probed using Raman spectroscopy by following the phonon modes of ZnO. Under the resonant excitation the temperature at the surface of the AuZnO NRs reaches up to about 300 degrees C, resulting in almost 6 times higher apparent quantum yield (AQY) for photocatalytic degradation of methylene blue (MB) compared to the bare ZnO NRs. Under solar light irradiation the Au-ZnO NRs demonstrated visible light photocatalytic activity twice that of what was achieved with bare ZnO NRs, while significantly reduced the activation energy required for the photocatalytic reactions allowing the reactions to occur at a faster rate.

  • 64. Borah, Sandhya Banti Dutta
    et al.
    Baruah, Sunandan
    Mohammed, Waleed S
    Dutta, Joydeep
    Water Research Center, Sultan Qaboos University.
    Heavy Metal Ion Sensing By Surface Plasmon Resonance on Gold Nanoparticles2014In: ADBU Journal of Engineering Technology, ISSN 2348-7305, Vol. 1Article in journal (Refereed)
    Abstract [en]

    Surface Plasmon resonance (SPR) based heavy metal ions sensor is one of the most sensitive sensor for detecting toxic metal ions. It is an inexpensive, portable and also feasible for real time detection. SPR sensor is a type of optical sensor in which toxic metal ions get adsorbed on the functionalized metal (mostly Au) film causes the change in refractive index of the metal (Au)-dielectric (sensing) medium. The change of the refractive index leads to a shift in the angular spectrum of the reflected light and can be accurately monitored by optical methods. In this paper,we are trying to optimize the detection level of heavy metal ions by surface plasmon resonance on gold nanoparticles using UV-VIS spectroscopy. Polymer like chitosan is being used with gold nanoparticles to detect copper and zinc ions and detection till very low concentrations of the toxic metal ions is obtained.

  • 65. Borah, Sandhya B.D.
    et al.
    Bora, Tanujjal
    Baruah, Sunandan
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Water Research Center, Sultan Qaboos University, Oman.
    Heavy metal ion sensing in water using surface plasmon resonance of metallic nanostructures2015In: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 1, no 1-2, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Heavy metal contamination in water and other ecosystems is one of the major environmental issues and already gaining significant attention across the world. For monitoring heavy metals in the environmental ecosystem, optical sensors are getting popular due to their high sensitivity and ease of use. Application of nanomaterials in the sensor elements further improves the sensitivity due to their large surface-to-volume ration, high reactivity, high degree of functionalization and size-dependent properties. This article mainly reviews the application of various metallic nanostructures for heavy metal ion sensing based on surface plasmon resonance (SPR). SPR sensors are widely applied in real time monitoring of heavy metals, chemical and biological analytes etc., because of their ability to efficiently detect and quantify these contaminants even at much diluted conditions (ng/L levels). In this article, SPR sensors fabricated with several metallic nanostructures, such as gold and silver, and their shape and size effects on sensor performance for heavy metal ion detection is discussed. Techniques used to improve the performance of such SPR sensors are also reviewed briefly.

  • 66. Bossel, C.
    et al.
    Dutta, Joydeep
    Laboratoire de Technologie des Poudres, Département des Matériaux, Ecole Polytechnique Fédérale de Lausanne, Switzerland.
    Houriet, R.
    Hilborn, J.
    Hofmann, H.
    Processing of nano-scaled silicon powders to prepare slip cast structural ceramics1995In: Journal of Materials Science and Engineering: A, ISSN 2161-6213, Vol. 204, no 1-2, p. 107-112Article in journal (Refereed)
    Abstract [en]

    For slip casting of ceramic powders it is necessary to have a well-defined and thus disagglomerated colloidal suspension. Proper selection of the solvent is required in order to achieve separation of the particles to obtain a homogenous mixture of the powders which is necessary for shaping complex geometrical structures, often used in structural ceramics. Here we report a preliminary investigation of the deagglomeration phenomena of nano-scaled silicon powders obtained by plasma induced dissociation of silane and compare it with silicon nitride powders prepared by laser induced condensation reactions and a commercial product (UBE SE E-10). The size dispersion of aggregates in colloidal suspensions, determined by photon correlation spectroscopy and sedimentation particle size analysis techniques, varies from 20 to 500 nm. Variation in the deagglomeration properties of the particles in different solvents depends on the surface property of the powders, and on the inter-particle interactions. These are studied with respect to the variations in the surface property of the powders in different solvents. Ethanol was found to be a suitable solvent for the colloidal suspension as the average aggregate radii of the silicon powders could be reduced to 80 nm.

  • 67. Carrot, G.
    et al.
    Valmalette, J. C.
    Plummer, C. J. G.
    Scholz, S. M.
    Dutta, Joydeep
    Hofmann, H.
    Hilborn, J. G.
    Gold nanoparticle synthesis in graft copolymer micelles1998In: Colloid and Polymer Science, ISSN 0303-402X, E-ISSN 1435-1536, Vol. 276, no 10, p. 853-859Article in journal (Refereed)
  • 68. Charinpanitkul, T.
    et al.
    Chanagul, A.
    Dutta, Joydeep
    School of Advanced Technologies, Asian Institute of Technology,Thailand.
    Rungsardthong, U.
    Tanthapanichakoon, W.
    Effects of cosurfactant on ZnS nanoparticle synthesis in microemulsion2005In: Science and Technology of Advanced Materials, ISSN 1468-6996, E-ISSN 1878-5514, Vol. 6, no 3-4 SPEC. ISS., p. 266-271Article in journal (Refereed)
    Abstract [en]

    ZnS nanoparticles with different morphology; spherical, ellipsoidal particles' nanotubes and nanorods, could be successfully synthesized from quaternary W/O microemulsion system. The morphology of the final products could be clearly confirmed by the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The effect of cosurfactant on size and morphology of the obtained products have been explored in this work. The key controlling parameters such as the molar ratio of water to surfactant (wo) and the reactant concentration, which affect the product characteristics, have also been investigated.

  • 69. Chaudhari, M. B.
    et al.
    Mohammed, W. S.
    Hornyak, G. L.
    Dutta, Joydeep
    Asian Institute of Technology, Center of Excellence in Nanotechnology, Thailand.
    Chromatic tuning of plasmon resonance of tri-layered composites: Silver, gold and copper nanoparticles for optical thin film colour filter2012In: Micro & Nano Letters, ISSN 1750-0443, E-ISSN 1750-0443, Vol. 7, no 2, p. 146-148Article in journal (Refereed)
    Abstract [en]

    The authors describe an approach to control colour shades by varying the volume fractions of three metal nanoparticles (NPs), Cu, Au and Ag, of fixed size and shape. The NPs were designed to match the absorption peaks of the three primary colours. Using the dynamic Maxwell Garnett equation, an analytical model is extracted that calculates the volume fraction value of each metal for the desired transmission red, green and blue values. The model considers the cross-talk between colours because of the broadening of the plasmon peaks. Maximum error of 10% was observed when producing secondary colour and grey shades.

  • 70. Courteille, C.
    et al.
    Dorier, J. -L
    Dutta, J.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Hollenstein, Ch.
    Howling, A. A.
    Stoto, T.
    Visible photoluminescence from hydrogenated silicon particles suspended in a silane plasma1995In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 78, no 1, p. 61-66Article in journal (Refereed)
  • 71. Danwittayakul, S.
    et al.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology.
    Two step copper impregnated zinc oxide microball synthesis for the reduction of activation energy of methanol steam reformation2013In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 223, p. 304-308Article in journal (Refereed)
    Abstract [en]

    Cu/ZnO microball catalysts were prepared by a two-step process, where ZnO nanorods supports were first grown hydrothermally followed by the impregnation of copper nanoparticles. Catalytic activities for methanol steam reforming by using Cu/ZnO microball were found to increase with higher copper content. Addition of urea during the metal impregnation process was found to enhance the methanol steam reforming catalytic activity attributed to the larger surface area of the catalyst. Activation energies of synthesized catalyst and CuZnAl commercial catalyst were calculated from the Arrhenius plots of the rate of reaction and were found to affect hydrogen yield. The lowest activation energy of 4.74 kJ mol(-1) was achieved for the optimized catalyst which was half of the activation energy of commercial catalysts.

  • 72. Danwittayakul, S.
    et al.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Zinc oxide nanorods based catalysts for hydrogen production by steam reforming of methanol2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 7, p. 5518-5526Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) nanorods were epitaxially grown on porous cordierite support by a hydrothermal process and utilized for catalyzing methanol steam reforming (MSR) reaction. Catalytic activity of ZnO nanorods for MSR process was correlated to the terminated surfaces of ZnO crystallites. Copper (Cu), palladium (Pd) and gold (Au) nanoparticles infused ZnO nanorods were prepared by in-situ precipitation of the metals on the nanorods. 28% hydrogen selectivity was observed with Cu/ZnO nanorods (Cu/10Zn), while Pd/ZnO nanorods and (Pd/10Zn) showed slightly lower activity. Higher catalytic activity of copper and palladium impregnated ZnO nanorods can be attributed to the synergistic combination of bimetallic oxides. In contrast, Au/ZnO nanorods (Au/10Zn) showed very high activity for methanol dehydrogenation and higher than 97% methanol conversion was achieved for operating temperatures as low as 200 degrees C.

  • 73. Danwittayakul, Supamas
    et al.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Controlled growth of zinc oxide microrods by hydrothermal process on porous ceramic supports for catalytic application2014In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 586, p. 169-175Article in journal (Refereed)
    Abstract [en]

    The growth of zinc oxide (ZnO) microrods on porous ceramic substrates by mild hydrothermal process was studied. One-dimensional ZnO microrods were grown on ZnO nanoparticle seeded substrates by using equimolar concentration of zinc nitrate and hexamethylenetetramine at temperatures lower than 100 degrees C. We found that the growth of ZnO microrods on alumina and diatomite substrates were affected due to hydrolysis of substrate surfaces. Stunted ZnO microrod growth on gamma-alumina and diatomite substrates were attributed to arise due to the degradation of hexamine molecules in the growth solution. Adjusting the pH prior to the growth of ZnO microrods on both alumina and diatomite lead to the growth of ZnO microrods similar to what is observed on flat glass substrates. Cordierite does not hydrolyze easily and hence ZnO microrods with aspect ratio as high as 24, were obtained without any pH control of the growth solution. Copper nanoparticles deposited on ZnO microrods were utilized as a catalyst for methanol steam reforming and about 14% hydrogen yield was obtained with almost 90% methanol conversion at reforming temperature of 350 degrees C.

  • 74. Danwittayakul, Supamas
    et al.
    Jaisai, M.
    Koottatep, T.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology,Thailand.
    Enhancement of photocatalytic degradation of methyl orange by supported zinc oxide nanorods/zinc stannate (ZnO/ZTO) on porous substrates2013In: Industrial and Engineering Chemistry Research, ISSN 0888-5885, Vol. 52, no 38, p. 13629-13636Article in journal (Refereed)
    Abstract [en]

    Dye wastewater from textile industries is reported to be a major river pollutant. Zinc stannate (ZTO) was grown directly on zinc oxide (ZnO) nanorod-coated polyester fiber membranes and porous ceramic substrates by a mild hydrothermal method, where the nanorods supplied zinc ions for ZTO growth. Photocatalytic degradation of a methyl orange aqueous solution under UV-light irradiation was monitored for up to 3 h duration. The higher photocatalytic activity of ZnO/ZTO catalysts on ceramic substrates was attributed to the large surface area of the nanocomposites. 50% methyl orange and similar to 95% methyl orange could be degraded within 1 and 3 h of UV-light irradiation, respectively, by using the porous-ceramic-supported catalysts (C-ZnO/10ZTO), because of efficient charge separation. Moreover, the formation of ZTO islands on ZnO nanorods led to an enhancement in the photocatalytic activity in the exposed areas of electron-rich ZnO nanorods.

  • 75. Danwittayakul, Supamas
    et al.
    Jaisai, Mayuree
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technolog, Thailand.
    Efficient solar photocatalytic degradation of textile wastewater using ZnO/ZTO composites2015In: Applied Catalysis B: Environmental, ISSN 0926-3373, Vol. 163, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Zinc oxide/zinc tin oxide (ZnO/ZTO) nanocomposites were synthesized on porous ceramic support using a simple and economical hydrothermal technique for photocatalytic degradation of organic dyes. One dimensional ZnO nanorods were grown epitaxially on ZnO nanoparticles seeded substrates in a chemical bath with different growth solution concentrations followed by the synthesis of zinc tin oxide (ZTO) in an autoclave. Comparison of photocatalytic activity of pure ZnO nanorod catalysts with different dimensions on the degradation of methylene blue showed that ZnO nanorods (ZnO20 mM) with the highest specific surface area (45 m(2) g(-1)) are 13% more active than those with lower surface areas ZnO nanorod catalysts (ZnO1 mM, ZnO5 mM and ZnO10 mM; 20-39 m(2) g(-1)). To further enhance photocatalytic activity, we composited ZnO with ZTO and found that ZnO/15ZTO can be a better photocatalyst improving 16% degradation efficiency attributed to the reduction of electron-hole recombination by charge carrier separation in the composites. Moreover, ZnO/15ZTO showed 50% Photocatalytic degradation efficiency and 77% COD removal of textile waste water when irradiated by sunlight. ZnO/ZTO monolith shows much promise to be an attractive photocatalyst for solar photocatalytic application.

  • 76. Danwittayakul, Supamas
    et al.
    Lakshman, K.
    Al-Harthi, S.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Enhanced hydrogen selectivity via photo-engineered surface defects for methanol steam reformation using zinc oxide-copper nanocomposite catalysts2014In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 471, p. 63-69Article in journal (Refereed)
    Abstract [en]

    Methanol steam reformation (MSR) to produce hydrogen (H-2) gas using copper on zinc oxide (Cu/ZnO) supported catalysts is attractive due to the simple and low cost preparation process of the catalyst. H-2 yield from MSR is proportional to total catalyst loading which can be tuned during catalyst preparation. By creating UV-c light induced surface defects on ZnO nanorods, we have shown improved copper (Cu) nano-particle distribution on the ZnO nanorods leading to better H-2 yield. Increase in Cu nanoparticle adsorption is achieved by in situ reduction of Cu ions by photo-generated electrons, facilitated by ZnO surface defects that act as high energy sites favorable for Cu ion adsorption and their subsequent growth into nanoparticles. The modulated Cu/ZnO catalyst increases H-2 selectivity by 57% along with a corresponding increase in CO content, which can be controlled by adjusting H2O:MeOH ratio in the precursor solution.

  • 77.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Non-Medical Applications of Chitosan Nanocomposite Coatings2019Other (Other academic)
  • 78. Dutta, Joydeep
    et al.
    Bacsa, W.
    Hollenstein, Ch.
    Microstructural properties of silicon powder produced in a low pressure silane discharge1995In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 77, no 8, p. 3729-3733Article in journal (Refereed)
  • 79. Dutta, Joydeep
    et al.
    Ganguly, G.
    Optically induced restructuring of a hydrogenated amorphous silicon thin-film surface1990In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 57, no 12, p. 1227-1229Article in journal (Refereed)
  • 80. Dutta, Joydeep
    et al.
    Hofmann, H.
    Houriet, R.
    Hofmeister, H.
    Hollenstein, C.
    Growth, microstructure and sintering behavior of nanosized silicon powders1997In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 127, no 1-3, p. 263-272Article in journal (Refereed)
  • 81. Dutta, Joydeep
    et al.
    Hofmann, H.
    Houriet, R.
    Valmalette, J. -C
    Hofmeister, H.
    Crystallization of nanosized silicon powder prepared by plasma-induced clustering reactions1997In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 43, no 11 A, p. 2610-2615Article in journal (Refereed)
    Abstract [en]

    Nanosized silicon powders were prepared by gas-phase cluster agglomeration reactions in a low-pressure silane plasma. The formation and agglomeration of clusters leading to the growth of primary particles of powder were studied by in-situ techniques including mass spectroscopy and laser light-scattering experiments. These powders, generally amorphous and crystallized in a reducing atmosphere, were studied in detail by Raman spectroscopy and high-resolution electron microscopy, which revealed a very rough surface of as-prepared single powder particles with structures of 1 to 2 nm. Upon 1-h annealing at temperatures between 300 and 600 °C, circular contrast features, 1.5 to 2.5 nm in size, are observed in the amorphous particles, which show medium-range order. A distinct onset of crystallization is observed at 700 °C with structures ranging from very small crystalline ordered regions of 2.5-3.5 nm in size to fast-grown multiple-twinned crystallites. The crystallization behavior is influenced by the clusters that form primary particles. Observed sintering behavior cannot be explained by a classical approach; hence, theoretical models need to be adapted to nanosized powders.

  • 82. Dutta, Joydeep
    et al.
    Houriet, R.
    Hofmann, H.
    Hofmeister, H.
    Cluster-induced crystallization of nano-silicon particles1997In: Nanostructured materials, ISSN 0965-9773, E-ISSN 1872-9150, Vol. 9, no 1-8, p. 359-362Article in journal (Refereed)
    Abstract [en]

    The possibility of producing from 20 nm to 100 nm sized silicon powders by plasma-induced reactions of silane including the formation of high-mass hydrogenated silicon anion clusters has been recently demonstrated. Careful HREM imaging showed circular contrast features, 1.5 to 2.5 nm in size, embedded in the amorphous particles which was attributed to the presence of medium range order in these regions. This non-homogeneous atomic distribution with partially ordered regions of a couple of nanometer dimension became more pronounced upon annealing upto the onset of crystallization. This observation and the formation of fivefold crystallites thereafter indicate that the clusters serve as seeds in the amorphous-to-crystalline transition.

  • 83. Dutta, Joydeep
    et al.
    Kroll, U.
    Chabloz, P.
    Shah, A.
    Howling, A. A.
    Dorier, J. -L
    Hollenstein, Ch.
    Dependence of intrinsic stress in hydrogenated amorphous silicon on excitation frequency in a plasma-enhanced chemical vapor deposition process1992In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 72, no 7, p. 3220-3222Article in journal (Refereed)
  • 84.
    Dutta, Joydeep
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH.
    Kunjali, Karthik Laxman
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    DESALINATION DEVICE AND METHOD OF MANUFACTURING SUCH A DEVICE2018Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A device (10) for capacitive deionization of an aqueous media containing dissolved ion species, said device comprising a cell with a first primary electrode (2) and a second primary electrode (3) arranged opposite the first primary electrode (2) and preferably separated by at least one non-conductive spacer (4, 4'). A third electrode (7) is arranged between the first and the second electrode. The third electrode (7) is grounded whereas the first and the second electrodes are polarized versus the grounded third electrode.

  • 85.
    Dutta, Joydeep
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH.
    Kunjali, Karthik Laxman
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Device for capacitive deionization of aqueous media and method of manufacturing such a device2019Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present disclosure relates to a device 10 for capacitive deionization of an aqueous media containing dissolved ion species. The device comprises a cell comprising a first primary electrode 2 and a second primary electrode 3 arranged opposite the first primary electrode 2 and preferably separated by at least one non-conductive spacer 4, 4'. A third electrode 7 is interposed between the first and the second electrode. The third electrode 7 is grounded whereas the first and the second electrodes are polarized versus the grounded third electrode. 

  • 86.
    Dutta, Joydeep
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Kunjali, Karthik Laxman
    Device for capacitive deionization of aqueous media and method of manufacturing such as a device2019Other (Other academic)
  • 87.
    Dutta, Joydeep
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    LAXMAN KUNJALI, Karthik
    Desalination Device and method of manufacturing such a device2018Other (Other academic)
  • 88. Dutta, Joydeep
    et al.
    McElheny, P. J.
    Suzuki, A.
    Ganguly, G.
    Matsuda, A.
    Hasezaki, K.
    Mashima, S.
    Effect of Ion Bombardment on the Properties of Hydrogenated Amorphous Silicon Prepared from Undiluted and Xenon-Diluted Silane1992In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 31, no 3B, p. L299-L302Article in journal (Refereed)
    Abstract [en]

    The contribution of ion bombardment to the growth of hydrogenated amorphous silicon prepared by plasma-enhanced chemical vapour deposition from silane and xenon-diluted silane source gases was studied by applying an external d.c. voltage to the substrate electrode. The role played by the xenon ions in the growth of the materials prepared from xenon-diluted silane source gas has been considered. It is demonstrated that the xenon ions are responsible for the growth of the materials showing stable photoconductivity behaviour under light illumination.

  • 89. Dutta, Joydeep
    et al.
    Perrin, J.
    Emeraud, T.
    Laurent, J. -M
    Smith, A.
    Pyrosol deposition of fluorine-doped tin dioxide thin films1995In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 30, no 1, p. 53-62Article in journal (Refereed)
  • 90. Dutta, Joydeep
    et al.
    Ray, S.
    Variations in structural and electrical properties of magnetron-sputtered indium tin oxide films with deposition parameters1988In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 162, no C, p. 119-127Article in journal (Refereed)
  • 91. Dutta, Joydeep
    et al.
    Reaney, I. M.
    Roca i Cabarrocas, P.
    Hofmann, H.
    Multilayered silicon/silicon nitride thin films deposited by plasma-CVD: Effects of crystallization1995In: Nanostructured Materials, Vol. 6, no 5-8, p. 843-846Article in journal (Refereed)
  • 92. Dutta, Joydeep
    et al.
    Roubeau, P.
    Emeraud, T.
    Laurent, J. -M
    Smith, A.
    Leblanc, F.
    Perrin, J.
    Application of pyrosol deposition process for large-area deposition of fluorine-doped tin dioxide thin films1994In: Thin Solid Films, Vol. 239, no 1, p. 150-155Article in journal (Refereed)
  • 93.
    Dutta, Joydeep
    et al.
    School of Advanced Technologies, Asian Institute of Technology, Thailand.
    Sugunan, A.
    Colloidal self-organization for nanoelectronics2004In: Proceedings ICSE 2004: 2004 IEEE International Conference on Semiconductor Electronics, IEEE , 2004, p. 146-148Conference paper (Refereed)
    Abstract [en]

    The major part of the expenses in modern IC manufacturing process is nowadays devoted to the R&D needed to optimize chip size, wafer size, defecrivity and interconnects- building up to keep Moore's law a reality. But the question is: Can circuits with sub-0.1μm dimensions be fabricated by the extension of current device production technologies? An interdisciplinary 'off the beaten path' approach is mandatory to overcome future limitations. One such approach is fabrication of devices (or at least parts of devices) by self-organization.

  • 94. Dutta, Joydeep
    et al.
    Unaogu, A. L.
    Ray, S.
    Barua, A. K.
    Comparison of the properties of hydrogenated microcrystalline silicon films deposited by photo-chemical-vapor deposition and glow-discharge deposition processes1989In: Journal of Applied Physics, Vol. 66, no 10, p. 4709-4714Article in journal (Refereed)
  • 95. Fallah, H.
    et al.
    Chaudhari, M.
    Bora, T.
    Harun, S. W.
    Mohammed, W. S.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Demonstration of side coupling to cladding modes through zinc oxide nanorods grown on multimode optical fiber2013In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 38, no 18, p. 3620-3622Article in journal (Refereed)
    Abstract [en]

    A novel concept is introduced that utilizes the scattering properties of zinc oxide nanorods to control light guidance and leakage inside optical fibers coated with nanorods. The effect of the hydrothermal growth conditions of the nanorods on light scattering and coupling to optical fiber are experimentally investigated. At optimum conditions, 5% of the incident light is side coupled to the cladding modes. This coupling scheme could be used in different applications such as distributed sensors and light combing. Implementation of the nanorods on fiber provides low cost and controllable nonlithography-based solutions for free space to fiber coupling. Higher coupling efficiencies can be achieved with further optimization.

  • 96. Fallah, Hoorieh
    et al.
    Harun, S. W.
    Mohammed, W. S.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Patumthani 12120, Thailand.
    Excitation of core modes through side coupling to multimode optical fiber by hydrothermal growth of ZnO nanorods for wide angle optical reception2014In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 31, no 9, p. 2232-2238Article in journal (Refereed)
    Abstract [en]

    Side coupling to core modes through zinc oxide (ZnO) nanorods grown around the fiber is demonstrated in this work. The scheme utilizes wet etching of the cladding region followed by hydrothermal growth of the nanorods. The combination of nanostructures and the optical fiber system is used to demonstrate a simple wide field of view (FOV) optical receiver. Core modes are excited by the light scattered in the region where the fiber core is exposed. The angular response of the receiver was tested using a nephlometer. Light coupling efficiency was extracted by deconvoluting the finite beam extinction from the measured power. The results were compared to a first-order analytical model in which the phase function is assumed to linearly shift with the incident angle. The trend of the experimental measurements agrees with the model. 180 degrees FOV is verified, and maximum coupling efficiency of around 2.5% for a single fiber is reported. Excitation of core modes through side coupling shows potential for the application of these devices in optical receivers and sensors.

  • 97.
    Fasanya, Opeoluw A.
    et al.
    Natl Res Inst Chem Technol, Petrochem Div, Zaria, Nigeria..
    Al-Hajri, Rashid
    Sultan Qaboos Univ, Petr & Chem Engn, Muscat, Oman..
    Ahmed, Omar U.
    Natl Res Inst Chem Technol, Petrochem Div, Zaria, Nigeria..
    Myint, Myo T. Z.
    Sultan Qaboos Univ, Dept Phys, Muscat, Oman..
    Atta, Abdulazeez Y.
    Ahmadu Bello Univ, Dept Chem Engn, Zaria, Nigeria..
    Jibril, Baba Y.
    Ahmadu Bello Univ, Dept Chem Engn, Zaria, Nigeria..
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Copper zinc oxide nanocatalysts grown on cordierite substrate for hydrogen production using methanol steam reforming2019In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 44, no 41, p. 22936-22946Article in journal (Refereed)
    Abstract [en]

    Hydrogen production from methanol rather than the traditional source, methane, is considered to be advantageous in ease of transportation and storage. However, the current copper-based catalysts utilized in methanol steam reforming are associated with challenges of sintering at high temperature and production of CO which could poison fuel cells. In addressing these challenges, ZnO nanorods were grown hydrothermally on the surface of cordierite and impregnated with Cu to produce catalysts for methanol steam reforming. The catalysts were characterized using SEM, XRD, FTIR, XPS, BET and Raman Spectroscopy. A fixed-bed reactor was used for testing the catalysts while the reaction products were characterized using a GC fitted with FID and TCD. The effects of temperature, methanol concentration and particle size of catalysts on methanol steam reforming were investigated. The experiments were carried out between 180 and 350 degrees C. CO selectivity of 0% was observed for temperatures between 180 and 230 degrees C for 0.8 MeOH:1H(2)O with an average H-2 selectivity of 98% for that temperature range. XPS showed that the catalyst was relatively unchanged after reaction while Raman spectroscopy revealed coke formation on the catalyst surface for reactions carried out above 300 degrees C. This shows that the catalyst is active and selective for the reaction. Publications LLC. Published by Elsevier Ltd. All rights reserved.

  • 98. Ganguly, G.
    et al.
    Dutta, J.
    Ray, S.
    Barua, A. K.
    Radiofrequency-plasma-deposited hydrogenated fluorinated silicon-carbon alloy films1989In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 40, no 6, p. 3830-3836Article in journal (Refereed)
  • 99. Ganguly, G.
    et al.
    Dutta, Joydeep
    Indian Association for the Cultivation of Science, India.
    Ray, S.
    Barua, A. K.
    Effect of ultraviolet irradiation on the white light degraded electronic properties of hydrogenated amorphous silicon films1989In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 55, no 19, p. 1975-1977Article in journal (Refereed)
  • 100. Giri, Anupam
    et al.
    Goswami, N.
    Pal, M.
    Zar Myint, M. T.
    Al-Harthi, S.
    Singha, A.
    Ghosh, B.
    Dutta, Joydeep
    Deparment in Nanotechnology, Water Research Center, Sultan Qaboos University, Al-Khoudh, Oman.
    Pal, S. K.
    Rational surface modification of Mn3O4 nanoparticles to induce multiple photoluminescence and room temperature ferromagnetism2013In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 1, no 9, p. 1885-1895Article in journal (Refereed)
    Abstract [en]

    Surface modification can have a significant influence on the materials behavior at the nanoscale and can lead to nanostructures with novel properties. Here, we demonstrate the surface modification induced multiple photoluminescence and room temperature ferromagnetic activation of Mn3O4 nanoparticles (NPs). Employing a systematic variation of the ligands, their functional groups and the structural position of the functional groups, we have identified the necessary and sufficient structural requirements of the surface co-ordinating ligands, in order to induce unprecedented optical/magnetic responses from the NPs. Using a multitude of spectroscopic techniques, we have investigated the mechanism behind the emergence of the multiple photoluminescence (PL), and it is revealed that the presence of a α-hydroxy carboxylate moiety in the ligands is necessary to activate the Jahn-Teller (J-T) splitting of Mn3+ ions on the NP surface and the corresponding d-d transitions along with the ligand-to-metal charge transfer transitions (LMCT, associated with Mn2+/3+-ligand interactions) is the key factor. However, the presence of a carboxylate group on the surface coordinating ligands is sufficient to activate the room temperature ferromagnetism of the NPs. Moreover, it has been observed that the ligands that induced the smallest crystal field splitting energy (CFSE) resulted in the strongest ferromagnetic activation of the NPs. Finally, the functionalized material has been identified as an efficient catalyst for the photo-degradation of a model cationic organic dye. Apart from the fundamental scientific interest, these results represent a promising route for the rational design of Mn 3O4 NPs adaptable to diverse applications.

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