Anju Nair - Academia.edu (original) (raw)

Papers by Anju Nair

Nucleation and Atmospheric Aerosols, 2018

Graphene - metal nanoparticle hybrids have received great attention due to their unique electroni... more Graphene - metal nanoparticle hybrids have received great attention due to their unique electronic properties, large specific surface area, very high conductivity and more charge transfer. Thus, it is extremely advantages to develop a simple and efficient process to disperse metal nanostructures over the surface of graphene sheets. Herein, we report a hydrothermal assisted strategy for developing reduced graphene oxide /Ag nanomorphotypes (cube, wire) for surface enhanced Raman scattering (SERS) applications, considering the advantages of synergistic effect of graphene and plasmonic properties of Ag nanomorphotypes.

Elsevier eBooks, 2018

Abstract Optical properties are among the most entrancing and helpful properties of nanomaterials... more Abstract Optical properties are among the most entrancing and helpful properties of nanomaterials and have been widely examined utilizing an assortment of optical spectroscopic strategies. Here, we present a detailed discussion covering the optical properties of metal nanoparticles, semiconductor nanoparticles, semiconductor quantum dots, metallic clusters, and carbon-based materials. It covers UV-Vis absorption and the photoluminescence (PL) properties, their control, and origins in various nanoparticles. Different mechanisms in which nanostructures exhibit PL are discussed. The optical-related applications of nanoparticles are explained in a detailed manner. We have critically analyzed the surface-enhanced Raman scattering and nonlinear optical limiting properties of different types of nanostructures.

Carbon, Jun 1, 2018

nitrogen sulfur co-doped reduced graphene oxide-Ag nano hybrids (sphere, cube and wire) for nonli... more nitrogen sulfur co-doped reduced graphene oxide-Ag nano hybrids (sphere, cube and wire) for nonlinear optical and SERS applications, Carbon (2018),

Nucleation and Atmospheric Aerosols, 2019

The need for metallic nanoparticle decorated nanocomposites of graphene oxide finds much attentio... more The need for metallic nanoparticle decorated nanocomposites of graphene oxide finds much attention by reason of their technological applications. Unlike the traditional methods, herein, we present a laser-assisted synthesis of silver nanoparticles that are anchored onto the graphene oxide (GO) by a one-step reaction. Second harmonics of an Nd:YAG laser is used for the in situ generation of Ag nanoparticles(Ag NPs) from a silver target ablated in an aqueous suspension of graphene oxide and thereby to make GO/Ag nanocomposite. UV-Vis and fluorescent spectroscopy and HRTEM upholds the optical and morphological characteristics of GO/Ag nanocomposite. Particularly, the GO/Ag nanocomposites exhibit excellent Surface Enhanced Raman Scattering(SERS) performance.

Optical Materials, Nov 1, 2017

We herein report the solvent effects on the aggregation, linear and nonlinear optical properties ... more We herein report the solvent effects on the aggregation, linear and nonlinear optical properties of silver nanoclusters synthesised using three solvents namely; ethanol, acetone and isopropanol. The Ag clusters were characterized using UVeVisible (UVevis) and photoluminescence (PL) spectroscopy, Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and open aperture Z-Scan measurements. Density functional theory (DFT) calculations at the B3PW91 level of theory, were done to compute the electric dipole, quadrupole, octapole and hexadecapole moment of mercaptosuccinic acid and mercaptosuccinic acid-Ag 9 cluster in three solvents. Linear optical properties show characteristic absorption profile with quantum confinement at different wavelengths for all the three clusters. The Open aperture Z-scan measurement in Ag clusters establishes the optical limiting properties which arise mostly from excited state absorption (ESA) and relatively weak saturable absorption (SA). The nonlinear optical behaviour varies within the three clusters with maximum optical limiting value obtained for the clusters synthesised using acetone. The theoretically computed hyperpolarizabilities together with z-scan measurements establish the solvent effect on the clusters and their potential applications in optical limiting devices.

Elsevier eBooks, 2018

Abstract Synthesis and characterization of nanomaterials plays a crucial role in material science... more Abstract Synthesis and characterization of nanomaterials plays a crucial role in material science and engineering. Nanoparticles exist in a number of shapes depending upon the synthesis procedures. Nanostructured materials showing different morphologies such as nanoparticles, nanotubes, nanowires, nanoflowers, nanocubes, etc. have been extensively studied and have shown considerable technological value in many applications. Morphological control in nanomaterials has a lot of significance, because of its striking properties from microscopic probes to nanoelectronic systems. These functional nanomaterials ensure the possibility of fabricating devices in the area of optics, electronics, magnetism, and photonics. Different shapes of nanomaterials include nanospheres, nanocube, nanowires, nanoreef, nanoclusters, and nanotubes. Microstructural characterization gives information about the morphology of different phases, number of phases, chemical composition, and crystallographic defects. Various properties of nanomaterials can be finely tuned based on its morphology, therefore a detailed study on the morphology of nanomaterials and its effect on the optical, electrical, magnetic, electronic, and thermal properties is required. Various morphological characterization techniques such as atomic force microscope, scanning electron microscope, transmission electron microscope, etc. were used to evaluate the particles in the nanoregime.

Nucleation and Atmospheric Aerosols, 2019

A simple and effective hydrothermal approach for synthesizing Ag-doped TiO 2 nanorods for photoca... more A simple and effective hydrothermal approach for synthesizing Ag-doped TiO 2 nanorods for photocatalytic application has been demonstrated. The structural, optical, morphological and photocatalytic properties of TiO 2 nanorods and Ag doped TiO 2 nanorods have been investigated. From the SEM results, it is confirmed that the prepared samples show vertically aligned rods like morphology. Furthermore, FTIR analysis shows a broad absorption band related to Ti-O vibration band. The samples TiO 2 and Ag doped TiO 2 nanorods exhibit enhanced photocatalytic efficiency towards degradation of Rh. B dye under visible light irradiation.

Nanomaterials, Aug 26, 2019

Gold decorated graphene-based nano-hybrids find extensive research interest due to their enhanced... more Gold decorated graphene-based nano-hybrids find extensive research interest due to their enhanced chemical catalytic performance and biochemical sensing. The unique physicochemical properties and the very large surface area makes them propitious platform for the rapid buildouts of science and technology. Graphene serves as an outstanding matrix for anchoring numerous nanomaterials because of its atomically thin 2D morphological features. Herein, we have designed a metal-graphene nano-hybrid through pulsed laser ablation. Commercially available graphite powder was employed for the preparation of graphene oxide (GO) using modified Hummers' method. A solid, thin gold (Au) foil was ablated in an aqueous suspension of GO using second harmonic wavelength (532 nm) of the Nd:YAG laser for immediate generation of the Au-GO nano-hybrid. The synthesis strategy employed here does not entail any detrimental chemical reagents and hence avoids the inclusion of reagent byproducts to the reaction mixture, toxicity, and environmental or chemical contamination. Optical and morphological characterizations were performed to substantiate the successful anchoring of Au nanoparticles (Au NPs) on the GO sheets. Remarkably, these photon-generated nano-hybrids can act as an excellent surface enhanced Raman spectroscopy (SERS) platform for the sensing/detection of the 4-mercaptobenzoic acid (4-MBA) with a very low detection limit of 1 × 10 −12 M and preserves better reproducibility also. In addition, these hybrid materials were found to act as an effective catalyst for the reduction of 4-nitrophenol (4-NP). Thus, this is a rapid, mild, efficient and green synthesis approach for the fabrication of active organometallic sensors and catalysts.

DAE SOLID STATE PHYSICS SYMPOSIUM 2018, 2019

Silver nanoparticles (Ag NPs) decorated graphene quantum dots (GQDs) are synthesized through easy... more Silver nanoparticles (Ag NPs) decorated graphene quantum dots (GQDs) are synthesized through easy bottomup approach with less number of chemical reagents. The as-synthesized Ag-GQDs were characterized via UV-Visible absorption Spectroscopy, Photoluminescence Spectroscopy, Time Resolved Fluorescence measurements, Raman Spectroscopy and Transmission Electron Microscopy for the realization of potential applications. EXPERIMENTAL Materials Citric acid monohydrate (CA), Sodium hydroxide pellets and Ascorbic acid were purchased from Merck, India and Silver Nitrate was obtained from Sigma-Aldrich. All samples were prepared in de-ionized (DI) water. Synthesis of graphene quantum dots and Ag NPs decorated GQDs GQDs were prepared via a modified method of previously reported bottom-up approach 6. 2g of CA taken in a 50 ml beaker was heated using a heating mantle at 220 o C. In 20 minutes, CA becomes liquated and the color changes from colorless to yellow and then to dark orange. The dark orange color confirms the formation of GQD. The obtained dark orange liquid was then added drop by drop into 80 ml of 5mg/ml NaOH solution, kept under vigorous

Journal of Saudi Chemical Society, 2019

Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem a... more Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem and vancomycin resistant strains isolated from cancer patients,

Applied Surface Science, 2018

Highlights  NG-AgNW hybrid is prepared by combining thermal treatment and polyol assisted synthe... more Highlights  NG-AgNW hybrid is prepared by combining thermal treatment and polyol assisted synthesis.  Insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and preventing its restacking.  AgNWs were introduced onto NG to enhance its electrochemical performance.  Smart electrode design enables NG-AgNW hybrid to be a high quality anode material.

Electrochimica Acta, 2017

Ni-NiO-CNT composite synthesized by swift and simple combustion process is investigated as anode ... more Ni-NiO-CNT composite synthesized by swift and simple combustion process is investigated as anode for Liion batteries (LIB) and also as an electro-catalyst for oxygen evolution reaction (OER) in alkaline medium. The binder free, electrical conductor less, free standing anode fabricated from Ni-NiO-CNT displays a stable capacity of 736 mAhg-1 at a current density of 200 mAg-1 for the investigated 50 cycles, the exhibited capacity being higher than the theoretical capacity of NiO and carbon. The hybrid composite also exhibits excellent OER activity, achieving current density of 10 mAcm-2 at a lower over potential (η) of 320 mV. The presence of Ni nanoparticles and porous sponge like structure of the composite is the main reason for this high performance. Such multifunctional materials could emerge as promising for realizing future energy storage and conversion approaches.

Langmuir, 2018

Investigation on the electrical and optical properties of spin coated polymernano composite thin ... more Investigation on the electrical and optical properties of spin coated polymernano composite thin films U. G. C.

New Journal of Chemistry, 2018

Herein we report a simple, one pot and rapid gamma-ray irradiation method for the fabrication of ... more Herein we report a simple, one pot and rapid gamma-ray irradiation method for the fabrication of PMMA–Ag nanocomposite films for multifunctional applications.

Scientific reports, Dec 12, 2016

Metal nanowires exhibit unusually high catalytic activity towards oxygen reduction reaction (ORR)... more Metal nanowires exhibit unusually high catalytic activity towards oxygen reduction reaction (ORR) due to their inherent electronic structures. However, controllable synthesis of stable nanowires still remains as a daunting challenge. Herein, we report the in situ synthesis of silver nanowires (AgNWs) over boron doped graphene sheets (BG) and demonstrated its efficient electrocatalytic activity towards ORR for the first time. The electrocatalytic ORR efficacy of BG-AgNW is studied using various voltammetric techniques. The BG wrapped AgNWs shows excellent ORR activity, with very high onset potential and current density and it followed four electron transfer mechanism with high methanol tolerance and stability towards ORR. The results are comparable to the commercially available 20% Pt/C in terms of performance.

Nucleation and Atmospheric Aerosols, 2018

Graphene - metal nanoparticle hybrids have received great attention due to their unique electroni... more Graphene - metal nanoparticle hybrids have received great attention due to their unique electronic properties, large specific surface area, very high conductivity and more charge transfer. Thus, it is extremely advantages to develop a simple and efficient process to disperse metal nanostructures over the surface of graphene sheets. Herein, we report a hydrothermal assisted strategy for developing reduced graphene oxide /Ag nanomorphotypes (cube, wire) for surface enhanced Raman scattering (SERS) applications, considering the advantages of synergistic effect of graphene and plasmonic properties of Ag nanomorphotypes.

Elsevier eBooks, 2018

Abstract Optical properties are among the most entrancing and helpful properties of nanomaterials... more Abstract Optical properties are among the most entrancing and helpful properties of nanomaterials and have been widely examined utilizing an assortment of optical spectroscopic strategies. Here, we present a detailed discussion covering the optical properties of metal nanoparticles, semiconductor nanoparticles, semiconductor quantum dots, metallic clusters, and carbon-based materials. It covers UV-Vis absorption and the photoluminescence (PL) properties, their control, and origins in various nanoparticles. Different mechanisms in which nanostructures exhibit PL are discussed. The optical-related applications of nanoparticles are explained in a detailed manner. We have critically analyzed the surface-enhanced Raman scattering and nonlinear optical limiting properties of different types of nanostructures.

Carbon, Jun 1, 2018

nitrogen sulfur co-doped reduced graphene oxide-Ag nano hybrids (sphere, cube and wire) for nonli... more nitrogen sulfur co-doped reduced graphene oxide-Ag nano hybrids (sphere, cube and wire) for nonlinear optical and SERS applications, Carbon (2018),

Nucleation and Atmospheric Aerosols, 2019

The need for metallic nanoparticle decorated nanocomposites of graphene oxide finds much attentio... more The need for metallic nanoparticle decorated nanocomposites of graphene oxide finds much attention by reason of their technological applications. Unlike the traditional methods, herein, we present a laser-assisted synthesis of silver nanoparticles that are anchored onto the graphene oxide (GO) by a one-step reaction. Second harmonics of an Nd:YAG laser is used for the in situ generation of Ag nanoparticles(Ag NPs) from a silver target ablated in an aqueous suspension of graphene oxide and thereby to make GO/Ag nanocomposite. UV-Vis and fluorescent spectroscopy and HRTEM upholds the optical and morphological characteristics of GO/Ag nanocomposite. Particularly, the GO/Ag nanocomposites exhibit excellent Surface Enhanced Raman Scattering(SERS) performance.

Optical Materials, Nov 1, 2017

We herein report the solvent effects on the aggregation, linear and nonlinear optical properties ... more We herein report the solvent effects on the aggregation, linear and nonlinear optical properties of silver nanoclusters synthesised using three solvents namely; ethanol, acetone and isopropanol. The Ag clusters were characterized using UVeVisible (UVevis) and photoluminescence (PL) spectroscopy, Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and open aperture Z-Scan measurements. Density functional theory (DFT) calculations at the B3PW91 level of theory, were done to compute the electric dipole, quadrupole, octapole and hexadecapole moment of mercaptosuccinic acid and mercaptosuccinic acid-Ag 9 cluster in three solvents. Linear optical properties show characteristic absorption profile with quantum confinement at different wavelengths for all the three clusters. The Open aperture Z-scan measurement in Ag clusters establishes the optical limiting properties which arise mostly from excited state absorption (ESA) and relatively weak saturable absorption (SA). The nonlinear optical behaviour varies within the three clusters with maximum optical limiting value obtained for the clusters synthesised using acetone. The theoretically computed hyperpolarizabilities together with z-scan measurements establish the solvent effect on the clusters and their potential applications in optical limiting devices.

Elsevier eBooks, 2018

Abstract Synthesis and characterization of nanomaterials plays a crucial role in material science... more Abstract Synthesis and characterization of nanomaterials plays a crucial role in material science and engineering. Nanoparticles exist in a number of shapes depending upon the synthesis procedures. Nanostructured materials showing different morphologies such as nanoparticles, nanotubes, nanowires, nanoflowers, nanocubes, etc. have been extensively studied and have shown considerable technological value in many applications. Morphological control in nanomaterials has a lot of significance, because of its striking properties from microscopic probes to nanoelectronic systems. These functional nanomaterials ensure the possibility of fabricating devices in the area of optics, electronics, magnetism, and photonics. Different shapes of nanomaterials include nanospheres, nanocube, nanowires, nanoreef, nanoclusters, and nanotubes. Microstructural characterization gives information about the morphology of different phases, number of phases, chemical composition, and crystallographic defects. Various properties of nanomaterials can be finely tuned based on its morphology, therefore a detailed study on the morphology of nanomaterials and its effect on the optical, electrical, magnetic, electronic, and thermal properties is required. Various morphological characterization techniques such as atomic force microscope, scanning electron microscope, transmission electron microscope, etc. were used to evaluate the particles in the nanoregime.

Nucleation and Atmospheric Aerosols, 2019

A simple and effective hydrothermal approach for synthesizing Ag-doped TiO 2 nanorods for photoca... more A simple and effective hydrothermal approach for synthesizing Ag-doped TiO 2 nanorods for photocatalytic application has been demonstrated. The structural, optical, morphological and photocatalytic properties of TiO 2 nanorods and Ag doped TiO 2 nanorods have been investigated. From the SEM results, it is confirmed that the prepared samples show vertically aligned rods like morphology. Furthermore, FTIR analysis shows a broad absorption band related to Ti-O vibration band. The samples TiO 2 and Ag doped TiO 2 nanorods exhibit enhanced photocatalytic efficiency towards degradation of Rh. B dye under visible light irradiation.

Nanomaterials, Aug 26, 2019

Gold decorated graphene-based nano-hybrids find extensive research interest due to their enhanced... more Gold decorated graphene-based nano-hybrids find extensive research interest due to their enhanced chemical catalytic performance and biochemical sensing. The unique physicochemical properties and the very large surface area makes them propitious platform for the rapid buildouts of science and technology. Graphene serves as an outstanding matrix for anchoring numerous nanomaterials because of its atomically thin 2D morphological features. Herein, we have designed a metal-graphene nano-hybrid through pulsed laser ablation. Commercially available graphite powder was employed for the preparation of graphene oxide (GO) using modified Hummers' method. A solid, thin gold (Au) foil was ablated in an aqueous suspension of GO using second harmonic wavelength (532 nm) of the Nd:YAG laser for immediate generation of the Au-GO nano-hybrid. The synthesis strategy employed here does not entail any detrimental chemical reagents and hence avoids the inclusion of reagent byproducts to the reaction mixture, toxicity, and environmental or chemical contamination. Optical and morphological characterizations were performed to substantiate the successful anchoring of Au nanoparticles (Au NPs) on the GO sheets. Remarkably, these photon-generated nano-hybrids can act as an excellent surface enhanced Raman spectroscopy (SERS) platform for the sensing/detection of the 4-mercaptobenzoic acid (4-MBA) with a very low detection limit of 1 × 10 −12 M and preserves better reproducibility also. In addition, these hybrid materials were found to act as an effective catalyst for the reduction of 4-nitrophenol (4-NP). Thus, this is a rapid, mild, efficient and green synthesis approach for the fabrication of active organometallic sensors and catalysts.

DAE SOLID STATE PHYSICS SYMPOSIUM 2018, 2019

Silver nanoparticles (Ag NPs) decorated graphene quantum dots (GQDs) are synthesized through easy... more Silver nanoparticles (Ag NPs) decorated graphene quantum dots (GQDs) are synthesized through easy bottomup approach with less number of chemical reagents. The as-synthesized Ag-GQDs were characterized via UV-Visible absorption Spectroscopy, Photoluminescence Spectroscopy, Time Resolved Fluorescence measurements, Raman Spectroscopy and Transmission Electron Microscopy for the realization of potential applications. EXPERIMENTAL Materials Citric acid monohydrate (CA), Sodium hydroxide pellets and Ascorbic acid were purchased from Merck, India and Silver Nitrate was obtained from Sigma-Aldrich. All samples were prepared in de-ionized (DI) water. Synthesis of graphene quantum dots and Ag NPs decorated GQDs GQDs were prepared via a modified method of previously reported bottom-up approach 6. 2g of CA taken in a 50 ml beaker was heated using a heating mantle at 220 o C. In 20 minutes, CA becomes liquated and the color changes from colorless to yellow and then to dark orange. The dark orange color confirms the formation of GQD. The obtained dark orange liquid was then added drop by drop into 80 ml of 5mg/ml NaOH solution, kept under vigorous

Journal of Saudi Chemical Society, 2019

Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem a... more Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem and vancomycin resistant strains isolated from cancer patients,

Applied Surface Science, 2018

Highlights  NG-AgNW hybrid is prepared by combining thermal treatment and polyol assisted synthe... more Highlights  NG-AgNW hybrid is prepared by combining thermal treatment and polyol assisted synthesis.  Insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and preventing its restacking.  AgNWs were introduced onto NG to enhance its electrochemical performance.  Smart electrode design enables NG-AgNW hybrid to be a high quality anode material.

Electrochimica Acta, 2017

Ni-NiO-CNT composite synthesized by swift and simple combustion process is investigated as anode ... more Ni-NiO-CNT composite synthesized by swift and simple combustion process is investigated as anode for Liion batteries (LIB) and also as an electro-catalyst for oxygen evolution reaction (OER) in alkaline medium. The binder free, electrical conductor less, free standing anode fabricated from Ni-NiO-CNT displays a stable capacity of 736 mAhg-1 at a current density of 200 mAg-1 for the investigated 50 cycles, the exhibited capacity being higher than the theoretical capacity of NiO and carbon. The hybrid composite also exhibits excellent OER activity, achieving current density of 10 mAcm-2 at a lower over potential (η) of 320 mV. The presence of Ni nanoparticles and porous sponge like structure of the composite is the main reason for this high performance. Such multifunctional materials could emerge as promising for realizing future energy storage and conversion approaches.

Langmuir, 2018

Investigation on the electrical and optical properties of spin coated polymernano composite thin ... more Investigation on the electrical and optical properties of spin coated polymernano composite thin films U. G. C.

New Journal of Chemistry, 2018

Herein we report a simple, one pot and rapid gamma-ray irradiation method for the fabrication of ... more Herein we report a simple, one pot and rapid gamma-ray irradiation method for the fabrication of PMMA–Ag nanocomposite films for multifunctional applications.

Scientific reports, Dec 12, 2016

Metal nanowires exhibit unusually high catalytic activity towards oxygen reduction reaction (ORR)... more Metal nanowires exhibit unusually high catalytic activity towards oxygen reduction reaction (ORR) due to their inherent electronic structures. However, controllable synthesis of stable nanowires still remains as a daunting challenge. Herein, we report the in situ synthesis of silver nanowires (AgNWs) over boron doped graphene sheets (BG) and demonstrated its efficient electrocatalytic activity towards ORR for the first time. The electrocatalytic ORR efficacy of BG-AgNW is studied using various voltammetric techniques. The BG wrapped AgNWs shows excellent ORR activity, with very high onset potential and current density and it followed four electron transfer mechanism with high methanol tolerance and stability towards ORR. The results are comparable to the commercially available 20% Pt/C in terms of performance.