Department Of Chemistry

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Author: search.filters.author.Biswas, REnd date: 2020

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    Novel Green Approach for Fabrication of Ag2CrO4/TiO2/Au/r-GO Hybrid Biofilm for Visible Light-Driven Photocatalytic Performance
    (American Chemical Society, 2020) Biswas, R; Mete, S; Mandal, M; Banerjee, B; Singh, H; Ahmed, I; Haldar, K.K.
    Development of cutting edge materials using a benevolent ecologically cordial methodology is an ideal approach for heterogeneous visible light photocatalysis. A new biogenic photocatalyst was developed by coupling titanium dioxide (TiO2) decorated elongated rhombic shape silver chromate (Ag2CrO4) with gold (Au) and reduced graphene oxide (r-GO) for dye degradation applications under visible light. An ecologically positive methodology was utilized to develop the quaternary Ag2CrO4/TiO2/Au/r-GO nanostructures biofilm with gold and reduced graphene oxide (r-GO) via impregnation and in situ reduction technique in the presence of acacia gum. The structural properties and morphology of the Ag2CrO4/TiO2/Au/r-GO nanostructures were described by several spectroscopic and microscopic methods such as XRD, XPS, ATR-FTIR, Raman spectroscopy, FE-SEM, etc. Alteration with Au and r-GO decreased the band vitality and essentially improved the visible light ingestion of the quaternary Ag2CrO4/TiO2/Au/r-GO composite biofilm photocatalyst and slowed down the recombination process of the photogenerated electrons and holes. To demonstrate how such a unique heterostructured biofilm might produce more outstanding photocatalytic activity, we examined a comparison of the photocatalytic performances of Ag2CrO4/TiO2/Au/r-GO hybrid biofilm with different inner structures. The photocatalytic debasement of MB reached almost 97% within 52 min, and it has been found that the Ag2CrO4/TiO2/Au/r-GO biofilm increased the degradation rate of MB by a factor of 10.8, 6.5, and 3.1 in comparison with exposed Ag2CrO4, Ag2CrO4/TiO2, and Ag2CrO4/TiO2/Au biofilms, individually. Further, the high electron movement capacity of Ag2CrO4/TiO2/Au/r-GO biofilm was explored by photoelectrochemical investigation and TCSPC to comprehend the mechanistic insight of the superior activity of this composite nanostructures under visible light illumination. Hence, the present investigation describes a facile, eco-friendly, and biomimetic approach for the fabrication of Ag2CrO4/TiO2/Au/r-GO biofilm based photocatalyst using acacia gum. Copyright � 2020 American Chemical Society.
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    Fabrication of mesoporous titanium dioxide using azadirachta indica leaves extract towards visible-light-driven photocatalytic dye degradation
    (Elsevier, 2020) Dash, L; Biswas, R; Ghosh, R; Kaur, V; Banerjee, B; Sen, T; Patil, R.A; Ma, Y.-R; Haldar, K.K.
    An environmental benign, straightforward and financially savvy technique has been developed to fabricate mesoporous titanium dioxide (TiO2) nanostructure utilizing Azadirachta indica leaves extract. The aqueous extract of Azadirachta indica leaves act as a template which upon calcination at high temperature generated mesoporous TiO2. The structure of the mesoporous TiO2 was confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and isothermal gas adsorption-desorption (BET). It has been found that the crystallinity and pore diameter of mesoporous titanium dioxide (TiO2) depends on the amount of Azadirachta indica leaves extract, resulting in enhanced crystallinity with an increasing amount of Azadirachta indica leaves extract. The pore diameter was found somewhere in the range from 16.67 to 46.19 nm, and the BET surface area varies from 8.55–157.35 m2/g.. Finally, we have explored as-synthesized mesoporous TiO2 for visible-light-driven photocatalytic degradation of rhodamine 6 G (R6 G) dye. It is noteworthy that the photocatalytic degradation rate of R6 G in presence of as-synthesized mesoporous TiO2 depends only on the amount of plant extract used and not on temperature and other factors. This is presumably due to the increased optical band gap of TiO2. - 2020 Elsevier B.V.
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    Au/CdSe hybrid nanoflowers: a high photocurrent generating photoelectrochemical cells
    (Springer, 2019) Haldar, Krishan Kant; Biswas, R; Patra, A; Halder, K.K; Sen, T.
    Photoelectrochemical cell composed of solution-processed nanoflower heterostructure of Au core and eight CdSe petals was investigated for enhanced photocurrent generation. The electrode of CdSe nanorods displayed photocurrent density of 2.1 mA/cm 2 whereas the Au core CdSe nanoflower exhibited 4.6 mA/cm 2 corresponding to a 119% increase during photoelectrochemical cell performance. Both electrodes showed prompt response to the on/off cycles of light, the photocurrent gain (I Photon /I dark ) in CdSe nanorods is 124.7, while the value is 223.3 for Au/CdSe nanoflower, calculated from the growth-decay curves. Photoresponse time was dramatically improved for Au/CdSe nanoflower samples due to increasing in 66% incident photon-to-current emission. Electron lifetime of 21.63 and 48.71 ns was observed for the electrode of CdSe nanorods and Au/CdSe nanoflowers respectively. The prolonged electron lifetime in the case of the electrode of Au/CdSe nanoflowers was responsible for improving charge separation and as a consequence, higher photocurrent generation. © 2018, Springer Nature Switzerland AG.
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    Zn(II) Di-isobutyldithiocarbamate Complex Enabled Efficient Synthesis of Au/ZnS Nanocomposite Core-shell in One Pot
    (Wiley, 2019) Biswas, R; Singh, H; Banerjee, B; Haldar, Krishan Kant
    Here, we demonstrate a one pot synthesis of gold/zinc sulphide (Au/ZnS) core-shell type composite nanostructure via thermal decomposition of single molecular precursor Zn(II)di-isobutyldithiocarbamate complex. In these Au/ZnS core-shell type hybrid nanostructures where ZnS quantum dots are assembled onto Au nanoparticles surface were prepared via a facile and reproducible approach under mild conditions. The crystalline nature and interface of these Au/ZnS core-shell type composite nanostructures were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High-resolution transmission electron microscopy (HRTEM) and inverted TEM images. Here Zn(II)di-isobutyldithiocarbamate complex acts as ZnS source as well as reducing and stabilizing agent for Au 0 at their nanoscale range by coating in the reaction medium. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Noble copper-silver-gold trimetallic nanobowls: An efficient catalyst
    (Academic Press, 2019) Haldar, Krishna Kanta; Tanwar, S; Biswas, R; Sen, T; Lahtinen, J.
    We demonstrated the design of tiny bowls of copper-silver-gold (Cu-Ag-Au) alloy type noble trimetallic nanocrystals with a unique shape. All the structural characterizations confirm the presence of copper (Cu), silver (Ag), and gold (Au) in the trimetallic nanobowls. Finally, we examined the catalytic efficiency of trimetallic Cu-Ag-Au nanobowls for reduction of 4-nitrophenol to 4-aminophenol and found that these nanobowls were 14, 23 and 43-fold more active than each of the constituent metals, Au, Cu and Ag, respectively. © 2019 Elsevier Inc.