Department of Chemistry

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Author: search.filters.author.Basu, MrinmoyeeEnd date: 2019

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Now showing 1 - 10 of 62
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    Construction of CuS/Au Heterostructure through a Simple Photoreduction Route for Enhanced Electrochemical Hydrogen Evolution and Photocatalysis
    (Springer Nature, 2016-10-05) Pande, Surojit; Basu, Mrinmoyee; Nazir, Roshan
    An efficient Hydrogen evolution catalyst has been developed by decorating Au nanoparticle on the surface of CuS nanostructure following a green and environmental friendly approach. CuS nanostructure is synthesized through a simple wet-chemical route. CuS being a visible light photocatalyst is introduced to function as an efficient reducing agent. Photogenerated electron is used to reduce Au(III) on the surface of CuS to prepare CuS/Au heterostructure. The as-obtained heterostructure shows excellent performance in electrochemical H2 evolution reaction with promising durability in acidic condition, which could work as an efficient alternative for novel metals. The most efficient CuS-Au heterostructure can generate 10 mA/cm2 current density upon application of 0.179 V vs. RHE. CuS-Au heterostructure can also perform as an efficient photocatalyst for the degradation of organic pollutant. This dual nature of CuS and CuS/Au both in electrocatalysis and photocatalysis has been unveiled in this study.
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    Metal and Metal Oxide Nanostructure on Resin Support
    (Wiley, 2011-07-11) Basu, Mrinmoyee
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    Gram Level Synthesis of Lead-Free Solder in the Nanometer Length Scale Obtained from Tin and Silver Compounds Using Silicone Oil
    (ACS, 2008) Basu, Mrinmoyee
    A straightforward route to gram level synthesis of a pure phase of the Sn−Ag nanoalloy in an eutectic composition (Sn/Ag 96.5:3.5) in silicone oil is reported. The composition, morphology, and microstructure of the alloy were fully characterized. In a mixture of ethylene glycol and silicone oil, direct reduction of Sn(II) acetate and Ag(I) nitrate gave the Sn−Ag nanoalloy. The nanoalloy disintegrates by sonication and reforms by heating, leading to smaller particles with a melting point as low as 128 °C.
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    Resin-Immobilized CuO and Cu Nanocomposites for Alcohol Oxidation
    (ACS, 2008) Basu, Mrinmoyee; Pande, Surojit
    Resin immobilized stable, spherical CuO nanoparticles prepared in the presence of cyclodextrin (CD) act as catalysts for liquid phase alcohol oxidation in air. The catalytic activity of the CuO nanocomposites and its green chemistry approach make it superior to the related resin-bound Cu(0) nanocomposite. The effect of alcohol chain length and electron-donating or -withdrawing groups influence product yield. The nanocomposites exhibit good reusability, simple workup procedure, and a straightforward approach to aldehyde formation.
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    An Aminolytic Approach toward Hierarchical β-Ni(OH)2 Nanoporous Architectures: A Bimodal Forum for Photocatalytic and Surface-Enhanced Raman Scattering Activity
    (ACS, 2010) Basu, Mrinmoyee
    A surfactantless, trouble-free, and gentle wet chemistry approach has been used to interpret the precisely controlled growth of β-Ni(OH)2 with the assistance of ammonia and nickel acetate from seedless mild hydrothermal conditions. A thorough investigation of the reaction kinetics and product morphology with varied concentration of NH3 and different reaction times suggests that a putative mechanism of dissolution, recrystallization, and oriented attachment supports the intelligent self-assembly of nanobuilding blocks. Associated characterizations (FTIR, PXRD, FESEM, EDAX, HRTEM, and Raman) have identified it to be pure β-Ni(OH)2 without any signature of contamination. The assembled units result in porous frameworks (nanoflowers and nanocolumns) and are indeed full of communally intersecting nanopetals/nanoplates with both lengths and widths on the order of micrometer to nanometer length scale. The as-synthesized material could also be used as a precursor for nanometric black NiO under calcination. The hydroxide has been found to be a potent and environmentally benign material because it warrants its photocatalytic activity through dye mineralization. Finally, Ni(OH)2 has been photochemically derivatized with dosages of silver nanoparticles bringing a competent composite authority Ag@Ni(OH)2, to give a full-proof enhanced field effect of prolific SERS activity. In a nutshell, these results are encouraging and fetch new promise for the fabrication of a low-cost and high-yielding greener synthetic protocol for a functional material with promising practicability.
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    Exploration of Electrostatic Field Force in Surface-Enhanced Raman Scattering: An Experimental Investigation Aided by Density Functional Calculations
    (ACS, 2008-10-27) Basu, Mrinmoyee
    Surface chemical properties of metal nanoparticles must be tunable to create chemical specificity and are a key prerequisite for successful sensing and imaging platforms. To relate surface enhanced Raman scattering (SERS) to electrostatic field force, a simple colloidal chemistry approach has been deliberately exploited for syntheses of gold nanoparticles with negative and positive surface charges to study their interactions with charged analytes. We took up the challenge with sulfur-containing analytes because “Au−S” interaction is well-known. Thiocyanate ion, −SCN−, a well-known SERS analyte, has been proved to be chemically ligated/anchored on positively charged gold nanoparticles surface owing to favorable electrostatic attraction. The Au−S vibrational band at ∼240 cm−1 and blue-shifting of the −C≡N stretching frequency by ∼46 cm−1 in conjunction with its intensity enhancement by an order of ∼103 in the SERS spectrum clearly illustrate a chemisorption phenomenon. In contrast, physisorption of the −SCN− ion becomes evident on negatively charged colloid. Again, methylene blue has been shown to remain engrossed on the negatively charged gold surfaces. However, the electrostatic field force could not be accounted for from fluorescence quenching while methylaminopyrene was introduced because of the distance-dependence effect. The feasibility of such coordinative/chemical attachment also has been examined theoretically by density functional theory (DFT). Moreover, employment of this DFT calculation has been performed on five different metal−molecule interaction models to fruitfully interpret the experimental SERS findings and also the orientation of the SERS analyte. The observed Raman signals have been assigned from the potential energy distributions in terms of internal coordinates of adsorbate from the output of DFT calculations. The results thus provide a benchmark illustration of the value of DFT for aiding interpretation of adsorbate vibrational spectra attainable by using SERS.
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    New hydrothermal process for hierarchical TiO2nanostructures
    (RSC, 2009) Basu, Mrinmoyee; Pande, Surojit; Sarkar, Sougata
    Hydrothermolysis of inorganic Ti(IV) compounds (peroxo or sulfate) yields hierarchical titania nanocrystals of controlled morphologies on either a glass or resin surface.Semiconductors of metal chalcogenides have attracted much attention because of their stability and potential applications. Amongst all semiconductors, the nanocrystals of TiO2 have been investigated for a wide range of applications in solar cells, electronics, sensors, batteries and as photoelectrochromic, electroluminescent materials.1,2 These varied applications are dependent especially on the size, morphology, phase and crystallinity of the particles. The shape and size of nanosized materials depend on the crystallographic planes present in the nanocrystals. The physical, chemical and electronic properties of atoms in different crystallographic planes are different. Hence, the shape or size-controlled synthesis of anisotropic nanocrystals is becoming an important area in nanoscience and nanotechnology. Now, the problem is how to control these parameters of the nanocrystals with accomplished synthetic approaches which is a challenging job. Several techniques have been used for the growth of nanostructured TiO2viz., sol-gel processing, hydrolysis, thermal evaporation and metal–organic chemical vapor deposition.2 Templating method is one of the approaches to attain these confined structures on the sub-nanometer scale. It is also an effective way of obtaining nanostructures to increase the surface area. Titania powders or thin films in the form of tubes, rods, whiskers, wires, needles, and sheets have been synthesized in the nanoregime through various physical, chemical or electrochemical approaches.3,4 One-dimensional (1D) nanostructures, such as rods, wires, belts or tubes exhibit a wide range of electrical, optical and chemical properties that also strongly depend on both the shape and size. When the diameter of the nanorod, nanowire or nanotube becomes small, the physico-chemical properties of the one-dimensional nanostructures are clearly different from those of crystalline solids or even two-dimensional systems. Moreover, fabrication of complex architectures with three dimensional (3D) or highly ordered nanostructures is very much desirable in current materials synthesis, holding the promise of advanced applications in electronics, optoelectronics and self cleaning property involving TiO2.5
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    A Green Chemistry Approach for the Synthesis of Flower-like Ag-Doped MnO2 Nanostructures Probed by Surface-Enhanced Raman Spectroscopy
    (ACS, 2009) Basu, Mrinmoyee
    Novel hierarchical flower-like nanostructures of Ag-doped MnO2 have been obtained by facile wet chemical and photochemical routes. UV−visible absorption spectroscopy measurement reveals that doping of Ag nanoparticles in MnO2 nanostructures leads to a red shift of the absorption edge and reduces the optical band gap energy from 2.68 to 2.51 eV while compared with undoped MnO2. Raman study reveals that the band broadens and shifts toward higher wavenumbers as the MnO6 octahedron is contorted by Ag doping and thus the loss of translational symmetry activates otherwise Raman-forbidden oxygen vibrations. Finally, SERS activity upsurges from Ag-doped MnO2 with Rhodamine 6G and 2-aminothiophenol as probe molecules.
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    Room Temperature Ferromagnetic Ni Nanocrystals: An Efficient Transition Metal Platform for Manifestation of Surface-Enhanced Raman Scattering
    (ACS, 2009) Basu, Mrinmoyee
    A simple solid-phase synthetic approach has been deliberately exploited for the synthesis of room temperature ferromagnetic, phase pure, fcc Ni nanocrystals on resin matrix. Self-assembly directed chainlike hierarchical nanostructures on the matrix could be engendered from magnetic dipole−dipole interaction between the nanocrystallites. Then, a practical virtue of the transition metal nanoparticle, Ni, was expressed from the rich and high-quality vibrational information of a chelating ligand, 1,10-phenanthroline (phen), onto the magnetically separated metal particles. Thus, surface-enhanced Raman scattering (SERS) has emerged exclusively from the time-dependent surface complexation of the chemically adhered probe molecule. Finally, kinetic effect has bestowed Ni(II)-phen chelate which later on demonstrates unique SERS activity on fcc Ni nanocrystals. The results provide a benchmark illustration of the value of transition metal for aiding interpretation of the vibrational signature of the adsorbate attainable from SERS studies.