Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Centre for Nanotechnology Research

Environment-friendly and cost effective green CdS Quantum Dots (QDs) are synthesized using Azadirachta Indica extract as a novel non-toxic stabilizing agent and to excogitate its light harvesting potentiality for QD Sensitized Solar Cells (QDSSCs). The effect of different configuration of green CdS based QDSSCs viz (i) different phase of TiO2 photoanodes (ii) with and without ZnS passivating layer (iii) with Platinum counter electrodes (CE) and (iv) CuS CE have been investigated. Despite tralatitious SILAR CdS based QDSSC showed better efficiency (1.93%) than green CdS based QDSSC (0.77%), the later unveil higher photocurrent density (10.61 mA) possibly due to effective encapsulation of Azadirachta Indica which suppresses the surface defects in green CdS QDs favoring the transport of photo generated carriers. The work facilitate scope for cost effective and environment-friendly green synthesized CdS QDs that significantly modulated photovoltaic properties of QDs based solar cells in an inviolable condition. © 2020 The Author(s). Published by IOP Publishing Ltd.

World University root node

Vellore Campus

Fulltext

Materials Research Express

Facile synthesis of CdS Quantum dots for QDSSC with high photo current density

Chemistry of Materials

Checking in with Women Materials Scientists during a Global Pandemic: May 2020

Hydrogen production using novel catalysts is regarded as one of the most needed technology for the future economic needs and water splitting to give H2 gas, which is a challenging task for large-scale production. This work reports the synthesis of Meso-Cu-BTC metal organic framework and further used for understanding its role in electrochemical hydrogen evolution reaction (HER) in 1 M NaOH solution. Meso-Cu-BTC electrocatalyst showed a less overpotential of 89.32 mV and an onset potential of 25 mV with an appreciable current density. Results show a low Tafel slope of 33.41 mVdec-1 and long-term durability. Thus, the overall results show that Meso-Cu-BTC acted as a good candidate for electrocatalysis towards hydrogen evolution. © 2020 The Author(s). Published by IOP Publishing Ltd.

Department of Physics

School of Advanced Sciences

Department of Bio-Medical Sciences

School of Bio Sciences and Technology

Cu based Metal Organic Framework (Cu-MOF) for electrocatalytic hydrogen evolution reaction

IET Nanobiotechnology

Guest Editorial: Selected extended papers from the 2nd International Conference on Nanoscience and Nanotechnology (ICNAN 2019)

Graphene is an important material for the design of flexible and stretchable electronic and optoelectronic devices on account of its high Young’s modulus and generation of highly confined surface plasmons. In this work, we report the near to far-infrared (FIR) input frequencies required to generate the maximum electric field and magnetic field for the efficient propagation of surface plasmons for differently doped, micron-long, free-standing and poly(methyl methacrylate) (PMMA) sandwiched graphene sheets. The effect of the variation of doping of graphene, graphene sheet length and bent angle of the graphene sheet on the propagating electromagnetic field is analysed at the obtained input excitation frequencies using finite element method. Low attenuation of 0.034 and 0.234 dB along with relatively high confinement of  6 and  13 nm for the surface plasmons are achieved for micron-long, bent, highly doped, freely suspended and PMMA sandwiched graphene sheets at 193.5 and 190 THz, respectively. The knowledge of these optimized NIR–FIR input excitation frequencies producing maximum electric and magnetic field output at the end of graphene sheet is useful for designing compact and efficient graphene-based flexible and wearable devices for medical imaging applications. © 2020, Indian Academy of Sciences.

Electronics

School of Electronics Engineering

Chennai Campus

Bulletin of Materials Science

Efficient surface plasmon propagation on flexible free-standing and PMMA sandwiched graphene at optimized near to far-IR frequencies

Preparation of manganese ferrite (MnFe2O4) nanorods by the reduction of akaganeite seeds in the presence of oleylamine is reported. The Mn-doped β-FeOOH akaganeite seeds have been processed by the hydrolysis of metal-chloride salts in the presence of polyethylenimine (PEI) surfactant. The hydrophobic oleylamine capped nanorods are made hydrophilic using trisodium citrate as a phase transferring agent. The nanorods form with an aspect ratio of 5.47 and possess a high magnetisation value of 69 emu/g at an applied magnetic field of 1.5 T. The colloidal water dispersion of nanorods exhibits superior heating efficiency by the application of alternating magnetic field (AMF). A specific absorption rate value of 798 W/g is achieved at an applied AMF of field strength 500 Oe and frequency 316 kHz. Further, the citrate functionalised nanorods are capable of attaching with doxorubicin (DOX) electrostatically with a loading efficiency of 97% and the drug release is pH responsive. The DOX loaded nanorods show a promising effect on the apoptosis of MCF-7 as experimented in vitro. © 2020 Institution of Engineering and Technology. All rights reserved.

Synthesis of manganese doped β-FeOOH and MnFe2O4nanorods for enhanced drug delivery and hyperthermia application

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. © 2020, The Author(s).

Scientific Reports

Assessing magnetic and inductive thermal properties of various surfactants functionalised Fe3O4 nanoparticles for hyperthermia

Cost-effective solutions for improved performance, activity, and stability are the main concern for the development of energy-storage devices. Generally, reduced graphene oxide (rGO) supported cobalt ferrite (CoF) based electrodes possesses enhanced electrochemical properties in supercapacitor applications such as high specific capacitance (CS) and long cyclic stability due to the presence of multiple oxidation states of cobalt ions, high surface area, and porous nanostructure that enables fast ion-diffusion. Herein, we report a one-pot solvothermal synthesis of glycol functionalised CoF nanoparticles and the composite with rGO for the supercapacitor electrode. Further, bare CoF was annealed at 300 and 500 °C to evaluate the dependency glycol functionalization on the electrochemical behaviour. The CoF-rGO nanocomposites in alkaline (2 M KOH) electrolyte exhibit better electrochemical behaviour compared to bare and annealed CoF. CoF-rGO exhibits high CS of 551 F/g at a scan rate of 2 mV/s with 98% capacitance retention after 2000 cycles. The power law and Trasatti method provide a qualitative analysis of the diffusivity of the nanoparticles at the electrode/electrolyte interface. © 2020 Elsevier B.V.

Diamond and Related Materials

Electrochemical properties of CoFe2O4 nanoparticles and its rGO composite for supercapacitor

Heterogeneous SiNx based charge trap flash (CTF) which has varying N/Si ratio (x) along the thickness of the charge-trapping layer (CTL) shows improved program/erase (P/E) transients. In this work, we present the P/E model invoking different nature of traps in N-rich and Si-rich CTL and investigate the physical processes behind the P/E improvement observed in heterogeneous CTF. A set of coupled equations that include Poisson's and rate equations for electrons and holes are solved considering the variation of CTL physical parameters along the thickness. The electron/hole injection current is accurately computed by including quantum effects at Si/SiO2 interface and taking into account the field-dependent relaxation of the energetic injected carriers. The simulation results of our model are in close agreement with the experimentally observed characteristics for five different sets of CTF devices with standard, Si-rich and N-rich homogeneous, and discretely and linearly graded heterogeneous CTF. Our study points out that the improvement in program transient for the heterogeneous CTF devices is attributed to the variation of trap density and trap energy along the CTL thickness and not due to lateral tunneling between the traps. The improvement in erase saturation and speed is due to high electron emission from the traps in Si-rich layer near bottom oxide of heterogeneous CTL. © 2020 Elsevier Ltd

Superlattices and Microstructures

Modeling of program/erase transient in heterogeneous SiNx charge trap flash memories

This article reports the synthesis of MnFe2O4 nanoparticles (NPs) by thermal decomposition method in different solvents such as diphenyl ether, benzyl ether and 1-octadecene with varying boiling point (bp). The physical and chemical properties of all the NPs were systematically studied. The NPs prepared using benzyl ether as solvent formed in cubic shape whereas spherical particles are formed in diphenyl ether and 1-octadecene. The solvent plays a significant role in the reaction and influence the morphology of the NPs. The hydrophobic particles are made hydrophilic by ligand exchange using tetramethyl-ammonium 11-aminoundecanote and the colloidal dispersion of the NPs are used for magnetic induction in varying alternating magnetic field (AMF) of frequency 314 kHz. The specific absorption rates that measure the heat generation in NPs are found to vary with the concentration of the NPs as well as the field strength. The cubic shaped NPs shows comparatively better SAR than the spherical NPs. © 2020 The Author(s). Published by IOP Publishing Ltd.