Madhulika Sharma

Bio: Madhulika Sharma is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Quantum dot & Luminescence. The author has an hindex of 11, co-authored 23 publications receiving 384 citations. Previous affiliations of Madhulika Sharma include Indian Institutes of Technology & Barkatullah University.

Assessing magnetic and inductive thermal properties of various surfactants functionalised Fe 3 O 4 nanoparticles for hyperthermia

Abstract: This work reports the fabrication of magnetite (Fe3O4) nanoparticles (NPs) coated with various biocompatible surfactants such as glutamic acid (GA), citric acid (CA), polyethylene glycol (PEG), polyvinylpyrrolidine (PVP), ethylene diamine (EDA) and cetyl-trimethyl ammonium bromide (CTAB) via co-precipitation method and their comparative inductive heating ability for hyperthermia (HT) applications. X-ray and electron diffraction analyses validated the formation of well crystallined inverse spinel structured Fe3O4 NPs (crystallite size of ~ 8-10 nm). Magnetic studies confirmed the superparamagnetic (SPM) behaviour for all the NPs with substantial magnetisation (63-68 emu/g) and enhanced magnetic susceptibility is attributed to the greater number of occupations of Fe2+ ions in the lattice as revealed by X-ray photoelectron spectroscopy (XPS). Moreover, distinctive heating response (specific absorption rate, SAR from 130 to 44 W/g) of NPs with similar size and magnetisation is observed. The present study was successful in establishing a direct correlation between relaxation time (~ 9.42-15.92 ns) and heating efficiency of each surface functionalised NPs. Moreover, heat dissipated in different surface grafted NPs is found to be dependent on magnetic susceptibility, magnetic anisotropy and magnetic relaxation time. These results open very promising avenues to design surface functionalised magnetite NPs for effective HT applications.

Adsorption, photodegradation and antibacterial study of graphene???Fe3O4 nanocomposite for multipurpose water purification application

Abstract: Graphene–Fe3O4 (G–Fe3O4) composite was prepared from graphene oxide (GO) and FeCl3·6H2O by a one-step solvothermal route. The as-prepared composite was characterized by field-emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering and X-ray powder diffraction. SEM analysis shows the presence of Fe3O4 spheres with size ranging between 200 and 250 nm, which are distributed and firmly anchored onto the wrinkled graphene layers with a high density. The resulting G–Fe3O4 composite shows extraordinary adsorption capacity and fast adsorption rates for the removal of Pb metal ions and organic dyes from aqueous solution. The adsorption isotherm and thermodynamics were investigated in detail, and the results show that the adsorption data was best fitted with the Langmuir adsorption isotherm model. From the thermodynamics investigation, it was found that the adsorption process is spontaneous and endothermic in nature. Thus, the as-prepared composite can be effectively utilized for the removal of various heavy metal ions and organic dyes. Simultaneously, the photodegradation of methylene blue was studied, and the recycling degradation capacity of dye by G–Fe3O4 was analyzed up to 5 cycles, which remained consistent up to ∼97% degradation of the methylene blue dye. Although iron oxide has an affinity towards bacterial cells, its composite with graphene still show antibacterial property. Almost 99.56% cells were viable when treated with Fe3O4 nanoparticle, whereas with the composite barely 3% cells survived. Later, the release of ROS was also investigated by membrane and oxidative stress assay. Total protein degradation was analyzed to confirm the effect of the G–Fe3O4 composite on E. coli cells.

Visible light-driven novel nanocomposite (BiVO4/CuCr2O4) for efficient degradation of organic dye.

Abstract: In the present study, BiVO4/CuCr2O4 nanocomposites synthesized via a chemical route are applied as a photocatalyst for the degradation of methylene blue (MB) dye. The photocatalytic activity results indicated a substantial degradation of MB dye by ∼90% over the surface of nanocomposite catalyst under visible light illumination. The nanocomposite showed a photocatalytic activity for MB dye degradation which is three times higher compared to that of BiVO4. This has been attributed to photogenerated electron–hole pair charge separation. The prepared photocatalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption and photoluminescence spectroscopy. Furthermore, an oxidizing reagent such as H2O2 was added to the photocatalytic system, which may act as an alternative electron scavenger and resulting in a notably enhanced rate of pollutant destruction. In addition, the effect of polyaniline has also been studied by synthesizing an organic/inorganic hybrid material (BiVO4/CuCr2O4/PANI). It has been observed that 95% photodegradation of organic dye takes place on the nanocomposite surface with visible light. A possible mechanism explaining the origin of enhanced performance of nanocomposite and nanohybrid is proposed.

Study of electropolymerised polyaniline films using cyclic voltammetry, atomic force microscopy and optical spectroscopy

Abstract: Electropolymerisation of polyaniline (PANI) has been investigated using cyclic voltammetry in aqueous bath. The effect of dopant on the structure, morphology & optical properties of electrodeposited PANI has also been studied using x-ray diffraction (XRD), atomic force microscopy (AFM), optical absorbance & luminescence spectroscopy. It is shown that the presence of a neutral salt (KI) in the deposition matrix imparts enhanced crystallinity to PANI films.

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Positive Electrode Materials for Li-Ion and Li-Batteries†

Abstract: Positive electrodes for Li-ion and lithium batteries (also termed “cathodes”) have been under intense scrutiny since the advent of the Li-ion cell in 1991. This is especially true in the past decade. Early on, carbonaceous materials dominated the negative electrode and hence most of the possible improvements in the cell were anticipated at the positive terminal; on the other hand, major developments in negative electrode materials made in the last portion of the decade with the introduction of nanocomposite Sn/C/Co alloys and Si−C composites have demanded higher capacity positive electrodes to match. Much of this was driven by the consumer market for small portable electronic devices. More recently, there has been a growing interest in developing Li−sulfur and Li−air batteries that have the potential for vastly increased capacity and energy density, which is needed to power large-scale systems. These require even more complex assemblies at the positive electrode in order to achieve good properties. This r...

Graphene based metal and metal oxide nanocomposites: synthesis, properties and their applications

Abstract: Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials has increased exponentially. Particularly the development of easy preparation methods for graphene like materials, such as highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail the aspects of graphene-based inorganic nanocomposites.