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A series of α-Fe 2 O 3 -Bi 2 S 3 heterojunction materials were prepared by a one-step autocombustion method employing thiourea as fuel. The heterojunction materials were characterized using XRD, UV–Vis-DRS, FTIR, PL, XPS, FESEM, TEM and HRTEM analytical techniques. XRD study indicated presence of rhombohedral α-Fe 2 O 3 and orthorhombic Bi 2 S 3 in the heterojunction materials. The heterojunctions displayed better optical absorption in the visible region and enhanced charge carrier separation characteristics. The oxidation state of the constituent elements on the surface was established from XPS study. IR study showed the characteristic vibrational features of both α-Fe 2 O 3 and Bi 2 S 3 phases. Microscopic studies indicated presence of well dispersed α-Fe 2 O 3 nanorods in a continuous Bi 2 S 3 matrix. The α-Fe 2 O 3 nanorods were typically 30–50 nm in diameter and 120–150 nm in length growing isotopically in different direction from a single nucleation point. The calculated band positions of both components indicated a facile electrons transfer from the conduction band of α-Fe 2 O 3 to Bi 2 S 3 whereas migration of holes occurs in the reverse direction yielding a type-II heterojunction. The α-Fe 2 O 3 -Bi 2 S 3 heterojunctions materials were evaluated as selective and efficient photocatalyst for the hydrogen transfer reduction of nitroarenes under visible light illumination. Structurally diverse nitroarenes could be selectively reduced to the corresponding amines in high yield and purity using α-Fe 2 O 3 -Bi 2 S 3 as photocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: A series of MoO3–ZrO2 nanocomposite oxides with MoO3 content in the range of 2–20mol% were prepared by solution combustion method. Three different fuels namely urea, glycine and hexamethylenetetramine (HMTA) were used for the preparation of MoO3–ZrO2 oxides. For the sake of comparison, the MoO3–ZrO2 composite oxides were also prepared by impregnation of zirconia with molybdenum salt precursor and subsequent heat treatment. The synthesized nanomaterials were characterized by XRD, SEM, TEM and UV–vis spectroscopic technique. XRD study indicated selective stabilization of the tetragonal phase of zirconia in the presence of MoO3. The method of preparation was found to be crucial for the phase composition of zirconia in the composite oxide. The crystallite size and rms stain were calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles. With increase in the MoO3 content, the crystallite size of the tetragonal zirconia phase was found to be decreased. TEM study indicated the presence of small nanoparticles with size in the 5–10nm range. UV–vis study of the composite oxide materials revealed well dispersion of the molybdenum oxide component in the form of monomer, dimers and nanoclusters in the zirconia matrix. The nature of fuel was found to be crucial in determining the morphology and shape of the particles. [Copyright &y& Elsevier]

Abstract: Ultra-fine Al2O3 fibers were synthesized via electrospinning technique using PVP/ethanol polymer solution and aluminium acetate sol followed by calcinations at higher temperature. The formation, crystalline phase, surface morphology, fibers diameter and surface area of alumina ultra-fine fibers were characterized using FT-IR, TGA/DTA, XRD, SEM, TEM and BET analytical techniques. The results show that pure and crystalline α-Al2O3 ultra-fine fibers were formed with fiber diameter in the range of 100–500nm and BET surface area of the fibers were found to be 40m2/g. [Copyright &y& Elsevier]

Abstract: Pure ZrO2 and MoO3 (10mol%)-ZrO2 nanocomposite oxides were prepared by solution combustion method using glycine as fuel. The synthesized materials were characterized by X-ray diffraction (XRD), Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM) and UV–vis spectroscopic technique. XRD study revealed selective stabilization of the tetragonal phase of zirconia in presence of MoO3. The crystallite size was calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles as well as from TEM measurements. Oxide nanoparticles with size in the range of 5–40nm was observed depending upon the fuel content in the combustion mixture. UV–vis study indicated well dispersion of the molybdenum oxide component in the zirconia matrix in the form of isolated and cluster molybdates. The MoO3–ZrO2 nanocomposite oxide was used as an efficient and environmentally benign catalyst for the synthesis of octahydroquinazolinones by multicomponent condensation reaction of dimedone, urea and arylaldehydes in aqueous media as well as under solvent free condition using microwave irradiation. A series of zirconia based heterogeneous catalyst with different acidity and surface area were screened for this reaction. The MoO3 (10mol%)-ZrO2 catalyst was found to be highly active for the transformation with excellent yield and purity of the product in a short reaction time. [Copyright &y& Elsevier]

Abstract: A series of MoO3–ZrO2 composite oxide catalysts were prepared by coprecipitation and impregnation methods and characterized by XRD, Raman, UV–Vis, TEM and sorptometric techniques. Characterization studies indicated the presence of tetragonal zirconia phase and well dispersed MoO3 species as isolated and polymolybdate clusters in the composite oxide. The MoO3(20mol%)–ZrO2 material was used as efficient catalyst for synthesis of amidoalkyl naphthols under solvent free conditions using conventional as well as microwave heating. The results obtained clearly showed that the composite oxide catalyst was recyclable and highly efficient for the reaction giving good yield and purity of the products. [Copyright &y& Elsevier]

Abstract: Nanosized sulfated tin oxide (STO) particles dispersed in the micropores of Al-pillared clay were prepared by a precipitation–deposition method followed by heat treatment and sulfation. The Al-pillared clays (Al-P) was prepared by the intercalation of [Al13O4(OH)24(H2O)12]7+ clusters into the clay interlayers. The physicochemical characteristics of the STO/Al-P material were evaluated by using X-ray diffraction (XRD), infrared (IR), transmission electron microscopy (TEM) and sorptometric studies. XRD results indicate an expansion in the interlayer spacing upon pillaring. The layer structure is found to be retained after the dispersion of the STO particles. The TEM images indicate the presence of uniform STO particles with sizes in the 5–15nm range. The sorptometric study show a type I isotherm for both the Al-P and STO/Al-P material, indicating the presence of micropores. The pore volume of the parent-pillared clay was found to decrease upon supporting the STO particles. The STO/Al-P material was used as an environmentally benign, recyclable and efficient catalyst for the solvent-free synthesis of 3,4-dihydropyrimidin-2(1H)-ones, thiochromans, with selective protection of aldehyde groups such as 1,1-diacetates and coumarins. The STO/Al-P catalyst was highly active for the synthesis of the above-mentioned molecules. The protocol developed using this catalyst has many advantages over those of the conventional mineral acids used as catalysts. [Copyright &y& Elsevier]