Jyoti Jog

MOF derived porous carbon–Fe3O4 nanocomposite as a high performance, recyclable environmental superadsorbent

A high surface area carbon composite with Fe3O4 nanoparticles is synthesized by pyrolysis of an iron containing Metal Organic Framework (MOF). The composite can be prepared by annealing the MOF at different temperatures (500 °C and 600 °C), each case exhibiting unique properties in terms of the hydrophobic behaviour and surface area, resulting in specific applicability domains. We highlight the exceptional behaviour of this material as a magnetically separable and recyclable superadsorbent for removal and recovery of environmental pollutants (oil/hydrocarbon and dye/phenol).

Plasmonic light harvesting of dye sensitized solar cells by Au-nanoparticle loaded TiO2 nanofibers

We report a significant enhancement in the performance of dye sensitized solar cells by using in situ Au nanoparticle (Au NP) loaded TiO2 nanofibers (Au:TiO2 NFs) as the light harvesting (LH) layer as compared to the use of only TiO2 nanofibers (NFs) as the LH layer. The Au NP:TiO2 nanofibers are prepared by electro-spinning of a precursor mixture whereby nanostructured porous TiO2 nanofibers are formed and get in situ loaded with only 4–5 nm AuNPs. The as-synthesized nanofibers are characterized by X-ray diffraction, Raman, photoluminescence (PL) and Mott–Schottky analyses. The presence of gold nanoparticles shows considerable improvements in light harvesting and the electrochemical properties of TiO2 nanofibers. A remarkable enhancement in the efficiency by 25% is achieved with the AuNF LH layer as compared to 12% with the NF layer, over the value without any light harvesting layer. The IPCE and impedance analyses reveal commensurate improvements. The impedance study shows a decrease in the transport resistance (RTiO2) and an increment in the chemical capacitance and life time of the solar cell. Systematic analyses of the optical properties suggest that the enhanced light harvesting by Au NP loaded TiO2 nanofibers is caused by the role of plasmon-polariton modes at the distributed nanoscale Schottky junctions in the Au:TiO2 nanofibers.

Cu2O/ZnO hetero-nanobrush: hierarchical assembly, field emission and photocatalytic properties

Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu2O) nanoneedles to form a Cu2O/ZnO hetero-nanobrush assembly. This increases the overall aspect ratio, which helps to enhance the field emission properties of the system. Also, the charge separation and transport are facilitated because of the multiple p–n junctions formed at p-Cu2O/n-ZnO interfaces and quasi-1-D structures of both the materials, respectively. This helps to significantly enhance the photocatalytic properties. As compared to only Cu2O nanoneedles, the Cu2O/ZnO hetero-nanobrush shows excellent improvement in both field emission and photocatalytic applications.

Magnetite/CdTe magnetic?fluorescent composite nanosystem for magnetic separation and bio-imaging

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

A Quasi-Liquid Iontronic–Electronic Light-Harvesting Hybrid Photodetector with Giant Response

A heterostructure formed by a layer of agarose gel drop-cast on a hydrothermally grown layer of ZnO nanorods on fluorine-doped tin oxide (FTO)-coated glass is examined for photoresponse with a top platinum tip contact. This ionic-gel-based hybrid device shows three orders of magnitude higher photocurrent as compared to the case of bare ZnO nanorods film.

Catalyst free novel synthesis of graphene and its application in high current OFET and phototransistor based on P3HT/G composite

High quality graphene is synthesized by pyrolysis of poly (acrylic acid) sodium salt, a novel catalyst-free cost-effective process. A strong Raman signature at 2698 cm−1 and a small defect (D) band (D/G ratio) confirm the high quality of the synthesized material. Analysis of the Raman parameters implies that it is a 1 or 2 layered material. This graphene is then used to make its composite with semiconducting polymer P3HT for evaluation as a channel in an organic thin film transistor (OTFT) application. The FET based on P3HT-G (composite) yields an order of magnitude high mobility as compared to the case of only P3HT and high current carrying ability. It also exhibits higher on/off ratio as compared to only graphene based TFTs. The P3HT-G composite based FETs are also shown to exhibit improved photo-response as compared to the only P3HT case.

Electrospinning of PHBV/ZnO membranes: Structure and properties

Polyhydroxy butyrate-co-valerate (PHBV) — Zinc oxide (ZnO) nano composite fibers were prepared using electrospinning. The structural and optical properties were studied using Fourier transform infrared spectroscopy (FT-IR), Xray diffraction (XRD) and photoluminescence study (PL). The morphology observed with scanning electron microscope (SEM) revealed no significant changes in the nano composite fibers as compared to bare polymer. The low concentration of ZnO nanoparticles resulted in an increase in overall crystallinity of the polymer matrix which was confirmed from FT-IR and XRD results. The photoluminescence (PL) study indicated the quenching of visible emission in the composite fibers. The ratio of UV to visible emission (Iuv/Ivis) intensity was found to be 12.8 times enhanced in the composite fibers compared to bare ZnO nanoparticles. The nanofibrous mats are self supported and hence offer potential applications in optoelectronic devices and the biomedical imaging.

MAGNETIC AND DIELECTRIC PROPERTIES OF POLYMER-CERAMIC COMPOSITES SYNTHESIZED USING A MELT COMPOUND TECHNIQUE

Polymer composites have emerged as a new class of materials, which have attracted technologist as they display novel properties compared to traditional materials and dramatically improves the performance properties of polymer system. We have synthesized hexaferrite-polymer composites of Polyvinylidene Fluride (PVDF) with BaCa2Fe16O27 (2.0, 5.0 % wt/vol.) using a melt compounding technique. BaCa2Fe16O27 hexaferrite powder was prepared using a microemulsion technique and directly mixed in melted PVDF, following by a low temperature hot pressing. The composites of PVDF with various weight percent of BaCa2Fe16O27 (2.0 & 5.0% wt/vol.) were processed via melt mixing at 200°C, with 60 rpm for 5 minutes. The films of uniform thickness are about 0.5 mm is obtained by a compression molded instrument at 200°C under 5-ton pressure. The influence of BaCa2Fe16O27 hexaferrite contents on magnetic and dielectric properties of composite was investigated. The prepared PVDF- BaCa2Fe16O27 composite thick films were characterized for their magnetic; dielectric and thermal behavior employing magnetic, dielectric and thermal analysis (TGA/DTA). Maximum saturation magnetization was obtained for 5 % wt/vol. of barium calcium hexaferrite composite.