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Satyabrata Mohapatra - One of the best experts on this subject based on the ideXlab platform.
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enhanced co gas sensing properties of cu doped sno2 nanostructures prepared by a facile Wet Chemical Method
Physical Chemistry Chemical Physics, 2016Co-Authors: Neha Bhardwaj, Biswarup Satpati, Akhilesh Pandey, Monika Tomar, Vinay Gupta, Satyabrata MohapatraAbstract:We report the synthesis of Cu doped SnO2 nanostructures with enhanced CO gas sensing properties by a facile Wet Chemical Method. The effects of Cu doping on the structural and optical properties of SnO2 nanostructures were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) with energy dispersive X-ray spectroscopy, Raman spectroscopy and photoluminescence spectroscopy. FESEM studies revealed the presence of nanosheets and nanodisc-like structures in Cu doped SnO2 samples. Gas sensing studies showed that the sensor prepared using 1% Cu doped SnO2 nanostructures exhibits highly enhanced CO gas sensing properties as compared to pure SnO2 nanostructures and shows excellent selectivity for CO with negligible interference from CH4, CO2 and NO2. The possible mechanism for the enhanced CO gas sensing properties of Cu doped SnO2 nanostructures is proposed.
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enhanced photocatalytic activity of co doped zno nanodisks and nanorods prepared by a facile Wet Chemical Method
Physical Chemistry Chemical Physics, 2014Co-Authors: Sini Kuriakose, Biswarup Satpati, Satyabrata MohapatraAbstract:Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile Wet Chemical Method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.
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enhanced photocatalytic activity of ag zno hybrid plasmonic nanostructures prepared by a facile Wet Chemical Method
Beilstein Journal of Nanotechnology, 2014Co-Authors: Sini Kuriakose, Vandana Choudhary, Biswarup Satpati, Satyabrata MohapatraAbstract:We report the synthesis of Ag–ZnO hybrid plasmonic nanostructures with enhanced photocatalytic activity by a facile Wet-Chemical Method. The structural, optical, plasmonic and photocatalytic properties of the Ag–ZnO hybrid nanostructures were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–visible absorption spectroscopy. The effects of citrate concentration and Ag nanoparticle loading on the photocatalytic activity of Ag–ZnO hybrid nanostructures towards sun-light driven degradation of methylene blue (MB) have been investigated. Increase in citrate concentration has been found to result in the formation of nanodisk-like structures, due to citrate-assisted oriented attachment of ZnO nanoparticles. The decoration of ZnO nanostructures with Ag nanoparticles resulted in a significant enhancement of the photocatalytic degradation efficiency, which has been found to increase with the extent of Ag nanoparticle loading.
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structural optical and photocatalytic properties of flower like zno nanostructures prepared by a facile Wet Chemical Method
Beilstein Journal of Nanotechnology, 2013Co-Authors: Sini Kuriakose, Biswarup Satpati, Neha Bhardwaj, Jaspal Singh, Satyabrata MohapatraAbstract:Flower-like ZnO nanostructures were synthesized by a facile Wet Chemical Method. Structural, optical and photocatalytic properties of these nanostructures have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–vis absorption spectroscopy. SEM and TEM studies revealed flower-like structures consisting of nanosheets, formed due to oriented attachment of ZnO nanoparticles. Flower-like ZnO structures showed enhanced photocatalytic activity towards sun-light driven photodegradation of methylene blue dye (MB) as compared to ZnO nanoparticles. XRD, UV–vis absorption, PL, FTIR and TEM studies revealed the formation of Zn(OH)2 surface layer on ZnO nanostructures upon ageing. We demonstrate that the formation of a passivating Zn(OH)2 surface layer on the ZnO nanostructures upon ageing deteriorates their efficiency to photocatalytically degrade of MB.
Masato Kakihana - One of the best experts on this subject based on the ideXlab platform.
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sodium niobate nanbo3 powders synthesized by a Wet Chemical Method using a water soluble malic acid complex
Chemistry of Materials, 2002Co-Authors: Emerson R Camargo, Monica Popa, Masato KakihanaAbstract:Sodium niobate powders were prepared by the amorphous complex Method using a water-soluble Nb−malic acid complex and sodium carbonate. Niobium oxide pentahydrate was dissolved in hot oxalic acid solution, followed by the addition of NH3 (30%) until pH = 11, precipitating niobic acid that was added into a solution of dl-malic acid (MA) at a mole ratio of [MA]:[Nb] = 2:1. Na2CO3 was added and the solvent eliminated at 70 °C, forming a yellow gel without any segregation, which was calcined at 300 °C for 3 h. The (Na−Nb−MA) material was thermally treated in the range of temperatures from 400 to 900 °C for 1 h. Although NaNbO3 was obtained at low temperature (450 °C), residual carbon was identified only by UV−Raman spectroscopy in calcined powders up to 550 °C. Crystalline phase was determined by X-ray diffractometry, and the particle size of about 100 nm was estimated from scanning electron microscopy images.
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sodium niobate nanbo3 powders synthesized by a Wet Chemical Method using a water soluble malic acid complex
Chemistry of Materials, 2002Co-Authors: Emerson R Camargo, Monica Popa, Masato KakihanaAbstract:Sodium niobate powders were prepared by the amorphous complex Method using a water-soluble Nb−malic acid complex and sodium carbonate. Niobium oxide pentahydrate was dissolved in hot oxalic acid so...
Yongchang Liu - One of the best experts on this subject based on the ideXlab platform.
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controlled synthesis of high quality w y2o3 composite powder precursor by ascertaining the synthesis mechanism behind the Wet Chemical Method
Journal of Materials Science & Technology, 2020Co-Authors: Zhi Dong, Nan Liu, Chenxi Liu, Qianying Guo, Yongchang LiuAbstract:Abstract As an emerging preparation technology, Wet Chemical Method has been employed widely to produce lots of alloy materials such as W and Mo based alloys, owing to its unique technical advantages. Ascertaining the synthesis mechanism behind Wet Chemical Method is indispensable for controlled synthesis of high-quality W-Y2O3 composite powder precursor. The co-deposition mechanism of yttrium and tungsten component behind the Wet Chemical Method of preparing yttrium-doped tungsten composite nanopowder was investigated systematically in this work. A series of co-deposited composite powders fabricated under different acidity conditions were used as research targets for investigating the effect of surface composition and structure on co-deposition efficiency. It was found that white tungstic acid has more W OH bonds and much higher co-deposition efficiency with Y3+ ions than yellow tungstic acid. It is illustrated that the coordination reaction between W OH bonds on tungstic acid particles and Y3+ ions brings the co-deposition of yttrium and tungsten component into being. Through displacing H+ ions in W OH bonds, Y3+ ions can be adsorbed on the surface of or incorporated into tungstic acid particles in form of ligand. Consequently, to control and regulate Y2O3 content in powder precursor accurately, H+ ion concentration in Wet Chemical reaction should be in range of 0.55–2.82 mol L−1 to obtain white tungstic acid. Besides, H+ ion concentration also has prominent effect on the grain size and morphology of reduced powder precursor. The optimal value should be around 1.58 mol L−1, which can lead to minimum W grain size (about 17 nm) without bimodal structure. The Chemical mechanism proposed in this work could produce great sense to preparation of high-quality precursor for sintering high-performance Y2O3 dispersion strengthened W based alloys. Our work may also shed light on the approach to exploit analogous synthesis mechanism in other alloy systems.
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eliminating bimodal structures of w y2o3 composite nanopowders synthesized by Wet Chemical Method via controlling reaction conditions
Journal of Alloys and Compounds, 2019Co-Authors: Nan Liu, Zhi Dong, Chenxi Liu, Qianying Guo, Yongchang LiuAbstract:Abstract The bimodal distribution of tungsten grain size, which is also called bimodal structure, is a universal phenomenon in synthesizing tungsten based nanopowders by Wet Chemical Method, and could significantly deteriorate further sintering characteristics of the powders. In this paper, W-Y2O3 composite nanopowders with small grain size and no bimodal structure were synthesized by an improved Wet Chemical Method. It was found that reaction conditions, especially the hydrogen ion concentration(ρ(H+)) could significantly influence the microstructure and morphology of the prepared composite nanopowders and has an optimum value of approximately 0.16 mol L−1. W-Y2O3 composite nanopowders synthesized under this optimum value got not only the minimum average grain size, which is about 17 nm, but also the best grain size uniformity with no bimodal structure. The microstructure of co-deposited precursors and prepared powders was analyzed in detail to figure out the specific influence mechanism of ρ(H+), and it was indicated that ρ(H+) could influence the microstructure and the Y2O3 content of the reduced powders through affecting the fraction of precursor that has little yttrium content, which may lead to the bimodal distribution of tungsten grain size of the prepared powders. Furthermore, the formation mechanism of bimodal structure was systematically analyzed and a feasible Method was proposed to eliminate the bimodal structure. It is suggested that the bimodal distribution of tungsten grain size is attributed to the distribution of Y2O3 during hydrogen reduction process and can be well avoided by controlling ρ(H+).
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microstructure refinement in w y 2 o 3 alloy fabricated by Wet Chemical Method with surfactant addition and subsequent spark plasma sintering
Scientific Reports, 2017Co-Authors: Zhi Dong, Nan Liu, Chenxi Liu, Qianying Guo, Zeid A Alothman, Yusuke Yamauchi, Md Shahriar A Hossain, Yongchang LiuAbstract:With the aim of preparing high performance oxide-dispersion-strengthened tungsten based alloys by powder metallurgy, the W-Y2O3 composite nanopowder precursor was fabricated by an improved Wet Chemical Method with anion surfactant sodium dodecyl sulfate (SDS) addition. It is found that the employment of SDS can dramatically decrease W grain size (about 40 nm) and improve the size uniformity. What’s more, SDS addition can also remarkably improve the uniform dispersion of Y2O3 particles during the synthesis process. For the alloy whose powder precursor was fabricated by traditional Wet Chemical Method without SDS addition, only a few Y2O3 dispersoids with size of approximate 10–50 nm distribute unevenly within tungsten grains. Nevertheless, for the sintered alloy whose powder precursor was produced by improved Wet Chemical Method, the Y2O3 dispersoids (about 2–10 nm in size) with near spherical shape are dispersed well within tungsten grains. Additionally, compared with the former, the alloy possesses smaller grain size (approximate 700 nm) and higher relative density (99.00%). And a Vickers microhardness value up to 600 Hv was also obtained for this alloy. Based on these results, the employment of SDS in traditional Wet Chemical Method is a feasible way to fabricate high performance yttria-dispersion-strengthened tungsten based alloys.
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preparation of ultra fine grain w y2o3 alloy by an improved Wet Chemical Method and two step spark plasma sintering
Journal of Alloys and Compounds, 2017Co-Authors: Zhi Dong, Chenxi Liu, Qianying Guo, Na Liu, Yongchang LiuAbstract:Abstract The Y 2 O 3 doped tungsten composite powder was synthesized via an improved Chemical Method where the polymeric surfactant Polyvinyl Pyrrolidone (PVP, K17) addition and ultrasonic treatment were both innovatively employed. Consequently, the average tungsten grain size of 10.7 nm was obtained for the composite powder precursor. To suppress the grain growth, two-step spark plasma sintering (SPS) was employed for the consolidation of powder precursor. It was found that in the sintered W-Y 2 O 3 alloys, nano (2–10 nm) and submicron (100–300 nm) oxide particles were uniformly dispersed within tungsten grains and at tungsten grain boundaries, respectively. The average tungsten grain size of W-Y 2 O 3 alloys whose final sintering temperature are 1400 and 1600 °C are 450 and 550 nm, respectively. Both of them are much smaller than that reported in previous studies. Their corresponding Vickers microhardness is 543.2 and 729.1 Hv, respectively, also better than the values obtained in previous works. These results indicate that the improved Wet Chemical Method combined with ultrasonic treatment and PVP addition developed in our work is a promising way to fabricate high performance oxide-dispersion-strengthened tungsten based alloys with ultra-fine grain.
Sini Kuriakose - One of the best experts on this subject based on the ideXlab platform.
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enhanced photocatalytic activity of co doped zno nanodisks and nanorods prepared by a facile Wet Chemical Method
Physical Chemistry Chemical Physics, 2014Co-Authors: Sini Kuriakose, Biswarup Satpati, Satyabrata MohapatraAbstract:Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile Wet Chemical Method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.
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enhanced photocatalytic activity of ag zno hybrid plasmonic nanostructures prepared by a facile Wet Chemical Method
Beilstein Journal of Nanotechnology, 2014Co-Authors: Sini Kuriakose, Vandana Choudhary, Biswarup Satpati, Satyabrata MohapatraAbstract:We report the synthesis of Ag–ZnO hybrid plasmonic nanostructures with enhanced photocatalytic activity by a facile Wet-Chemical Method. The structural, optical, plasmonic and photocatalytic properties of the Ag–ZnO hybrid nanostructures were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–visible absorption spectroscopy. The effects of citrate concentration and Ag nanoparticle loading on the photocatalytic activity of Ag–ZnO hybrid nanostructures towards sun-light driven degradation of methylene blue (MB) have been investigated. Increase in citrate concentration has been found to result in the formation of nanodisk-like structures, due to citrate-assisted oriented attachment of ZnO nanoparticles. The decoration of ZnO nanostructures with Ag nanoparticles resulted in a significant enhancement of the photocatalytic degradation efficiency, which has been found to increase with the extent of Ag nanoparticle loading.
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structural optical and photocatalytic properties of flower like zno nanostructures prepared by a facile Wet Chemical Method
Beilstein Journal of Nanotechnology, 2013Co-Authors: Sini Kuriakose, Biswarup Satpati, Neha Bhardwaj, Jaspal Singh, Satyabrata MohapatraAbstract:Flower-like ZnO nanostructures were synthesized by a facile Wet Chemical Method. Structural, optical and photocatalytic properties of these nanostructures have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–vis absorption spectroscopy. SEM and TEM studies revealed flower-like structures consisting of nanosheets, formed due to oriented attachment of ZnO nanoparticles. Flower-like ZnO structures showed enhanced photocatalytic activity towards sun-light driven photodegradation of methylene blue dye (MB) as compared to ZnO nanoparticles. XRD, UV–vis absorption, PL, FTIR and TEM studies revealed the formation of Zn(OH)2 surface layer on ZnO nanostructures upon ageing. We demonstrate that the formation of a passivating Zn(OH)2 surface layer on the ZnO nanostructures upon ageing deteriorates their efficiency to photocatalytically degrade of MB.
V P N Nampoori - One of the best experts on this subject based on the ideXlab platform.
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erratum to synthesis of monocrystalline zinc oxide microrods by Wet Chemical Method for light confinement applications physica e 44 2012 2118 2123
Physica E-low-dimensional Systems & Nanostructures, 2013Co-Authors: Aparna Thankappan, Misha Hari, S Mathew, Santhi Ani Joseph, Debajeet K Bora, Artur Braun, Rolf Erni, V P N NampooriAbstract:Erratum to ‘‘Synthesis of monocrystalline zinc oxide microrods by Wet Chemical Method for light confinement applications’’ [Physica E 44 (2012) 2118–2123] Aparna Thankappan , Misha Hari , S. Mathew , Santhi Ani Joseph , Rolf Erni , Debajeet Bora , Artur Braun , V.P.N. Nampoori a International School of Photonics, Cochin University of Science and Technology (CUSAT), Cochin, India b Inter University Centre for Nanomaterials and Devices (IUCND), CUSAT, India c Center of Excellence in Lasers and Optoelectronic Sciences (CELOS), CUSAT, India d Laboratory for High Performance Ceramics, EMPA, Dubendorf, Switzerland e Electron Microscopy Center, EMPA, Dubendorf, Switzerland
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synthesis of monocrystalline zinc oxide microrods by Wet Chemical Method for light confinement applications
Physica E-low-dimensional Systems & Nanostructures, 2012Co-Authors: Aparna Thankappan, Misha Hari, S Mathew, Santhi Ani Joseph, Erni Rolf, Debajeet K Bora, Artur Braun, V P N NampooriAbstract:Abstract The growth of Zinc Oxide (ZnO) microrods by Wet Chemical Method, under prolonged treatment of zinc nitrate for 22 h in low temperature (80 °C) with hexamine is presented. The purpose was to obtain large microrods that can act as laser resonators with emission in the blue region. The electron microscopy and X-ray diffraction observations reveal that the ZnO microrods are single crystalline. We have done various optical characterizations in order to assess the suitability of the rods in photonic applications. Studies include optical absorption, fluorescence and photon backscattering. Room temperature optical measurements reveal that they have a large direct band gap of 3.7 eV and an emission at the visible and ultraviolet region and have excitation wavelength dependence. The backscattering studies clearly reveal the photon confinement effects, which is the first test of the material's self lasing action.
