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  • 1. Baruah, S.
    et al.
    Dutta, Joydeep
    School of Engineering and Technology, Asian Institute of Technology, Thailand.
    Effect of seeded substrates on hydrothermally grown ZnO nanorods2009In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 50, no 3, p. 456-464Article in journal (Refereed)
    Abstract [en]

    We report a study on the effect of seeding on glass substrates with zinc oxide nanocrystallites towards the hydrothermal growth of ZnO nanorods from a zinc nitrate hexahydrate and hexamethylenetetramine solution at 95 °C. The seeding was done with pre-synthesized ZnO nanoparticles in isopropanol with diameters of about 6–7 nm as well as the direct growth of ZnO nanocrystallites on the substrates by the hydrolysis of pre-deposited zinc acetate film. The nanorods grown on ZnO nanoparticle seeds show uniform dimensions throughout the substrate but were not homogenously aligned vertically from the substrate and appeared like nanoflowers with nanorod petals. Nanorods grown from the crystallites formed in situ on the substrates displayed wide variations in dimension depending upon the preheating and annealing conditions. Annealing the seed crystals below 350 °C led to scattered growth directions whereupon preferential orientation of the nanorods perpendicular to the substrates was observed. High surface to volume ratio which is vital for gas sensing applications can be achieved by this simple hydrothermal growth of nanorods and the rod height and rod morphology can be controlled through the growth parameters.

  • 2. Khaliullin, S. M.
    et al.
    Zhuravlev, V. D.
    Bamburov, V. G.
    Khort, Aliaksandr
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Roslyakov, S. I.
    Trusov, G. V.
    Moskovskikh, D. O.
    Effect of the residual water content in gels on solution combustion synthesis temperature2020In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 93, no 2, p. 251-261Article in journal (Refereed)
    Abstract [en]

    The composition of gels and xerogels, as well as their transformation during heating and dehydration, determine the thermochemistry of solution combustion synthesis reactions. An improved descriptive thermodynamic model of combustion processes was formulated on the basis of the investigated formation of complex compounds of metal ions with organic fuel (glycine, citric acid, urea, and PVA) in nitrate solutions. The intensity of SCS reactions was found to depend on the strength of Ni2+–ligand complexes. The effect of heat loss during combustion on the ΔTmax value was analyzed for the model system Ni(NO3)2·nH2O–Fuel–H2O. It was found the heat loss occurs due to the presence of various amounts of structurally-bound water in gels and xerogels before the combustion. [Figure not available: see fulltext.]

  • 3. Mahmood, Mohammad Abbas
    et al.
    Dutta, Joydeep
    Asian Institute of Technology, Thailand; Sultan Qaboos University, Oman.
    Microwave assisted hydrothermal synthesis of zinc hydroxystannate films on glass substrates2012In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 62, no 3, p. 495-504Article in journal (Refereed)
    Abstract [en]

    Zinc stannate (ZnSnO 3, Zn 2SnO 4) and its precursor, i.e. zinc hydroxystannate (ZnSn(OH) 6), have emerged as technological nanomaterials for different applications. Herein, we report synthesis of polycrystalline zinc hydroxystannate (ZHS) film on glass substrate through facile and efficient microwave assisted hydrothermal growth. The method comprises of three steps; deposition of ZnO seed films on glass substrates through spray pyrolysis, growth of ZnO nanorod arrays over the seeded substrates through microwave assisted hydrothermal method and transformation of the as-synthesized ZnO nanorod arrays into the ZHS films through microwave treatment in aqueous precursor solution of SnCl 4 and NaOH. The films were characterized by energy dispersive X-ray spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). The films contain two crystalline phases namely ZnO with [002] as preferred growth direction and ZnSn(OH) 6 preferably grown along [200] vector. The obtained ZHS films consist of crystals of exclusively cubic structure with sizes up to several microns. Microwave irradiation time, NaOH/SnCl 4 molar ratio, concentration of Sn 4+ ions, and the applied power are the four parameters which influence the size, aerial density and growth rate of ZHS microblocks.

  • 4.
    Ren, Yanan
    et al.
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Zheng, Dongmei
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Liu, Linyan
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Guo, Qiangsheng
    Shanghai Insititute Technol, Sch Chem & Environm Engn, Shanghai 201418, Peoples R China..
    Sha, Na
    Shanghai Insititute Technol, Sch Chem & Environm Engn, Shanghai 201418, Peoples R China..
    Zhao, Zhe
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    3DOM-NiFe2O4 as an effective catalyst for turning CO2 and H2O into fuel (CH4)2018In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 88, no 3, p. 489-496Article, review/survey (Refereed)
    Abstract [en]

    Three-dimensional ordered macroporous NiFe2O4 (3DOM-NFO) powder was synthesized through the direct templating method combined with the sol-gel combustion technique. Polymethyl methacrylate (PMMA) spheres with different sizes were used as the hard templates. In order to understand the effect of PMMA spheres mean size on the structure and catalytic activity of synthesized 3DOM-NFO, the detailed characterization of the material was carried out by XRD, SEM, BET, XPS, UV-VIS, and DRS techniques. Direct hydrogeneration production of CH4 from CO2 and H2O was used to evaluate the catalysis performance of 3DOM-NFOs. The production of CH4 evolution can reach 1040.8mol/g at 350 degrees C and ambient pressure when 300nm template was used. It was concluded that the specific surface area and moderate concentration of oxygen vacancies are the crucial factors affecting the catalysis properties. Reasonably high turnover number of 0.244 and high CH4 conversion efficiency of 0.897% were obtained in this study. 3DOM-NFO can be a promising catalyst for hydrocarbon fuel production by directly using CO2 and H2O as the safe and cheap feedstocks. [GRAPHICS] .

  • 5. Spijksma, Gerald I.
    et al.
    Seisenbaeva, Gulaim A.
    Fischer, Andreas
    Bouwmeester, Henny J. M.
    Blank, Dave H. A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kessler, Vadim G.
    The molecular composition of non-modified and acac-modified propoxide and butoxide precursors of zirconium and hafnium dioxides2009In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 51, no 1, p. 10-22Article in journal (Refereed)
    Abstract [en]

    Long-term storage at 0 A degrees C of a paraffin-sealed flask with commercial 70 wt% solution of zirconium n-propoxide in n-propanol resulted in crystallization of an individual oxoalkoxide complex Zr(4)O(O(n)Pr)(14)((n)PrOH)(2) in over 20% yield. The structure of this molecule can be described as a triangular Zr(3)(mu(3)-O)(OR)(10)(ROH) core of 3 edge-sharing octahedrons with an additional Zr(OR)(4)(ROH) unit attached through a pair of (mu-OR) bridges. Mass spectrometric and (1)H NMR investigation of the commercial samples of the most broadly applied zirconium and hafnium n-propoxides and n-butoxides indicate the presence of analogous species in the commercial alkoxide precursors. The content of oxo-alkoxide species in the commercial precursors has been estimated to be similar to 20% for n-propoxide and similar to 35% for zirconium n-butoxide. A new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(O(n)Pr)(O(i)Pr)(3)((i)PrOH)](2), from zirconium n-propoxide. A high yield has been observed (similar to 90%), indicative of an almost complete precursor transformation. Mass spectrometry has shown that the synthesized mixed ligand precursor is dimeric, which makes it an attractive alternative to zirconium n-propoxide. Addition of 1 eq of Acetylacetone to zirconium or hafnium alkoxide precursors results in formation of dimeric [M(OR)(3)(acac)](2) in high yields. These species have limited stability (much higher for Hf than for Zr) and transform in solution into hydrolysis-insensitive M(acac)(4) through very unstable M(acac)(3)(OR) intermediates containing 7-coordinated metal centers. This transformation can be followed kinetically in hydrocarbon solvents by (1)H NMR and is noticeably accelerated by addition of parent alcohols. The obtained results clearly reveal limited applicability of EXAFS and XANES techniques for the study of such systems, especially in the context of structure prediction.

  • 6. Sugunan, Abhilash
    et al.
    Warad, Hemant C.
    Boman, Mats
    Dutta, Joydeep
    Zinc oxide nanowires in chemical bath on seeded substrates: Role of hexamine2006In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 39, no 1, p. 49-56Article in journal (Refereed)
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