Showing papers by "Pawan K. Khanna published in 2021"

Magic-sized CdSe nanoclusters: a review on synthesis, properties and white light potential

Abstract: Magic-sized nanoclusters have gained tremendous attention from researchers as they offer applicability in a variety of fields ranging from chemistry and physics to electronics. The first report on magic-sized nanoclusters of CdSe gave impetus to deepen the understanding of the sub 2 nanometer (<2 nm) dimension regime of II–VI semiconductor quantum dots, which have been vastly documented in the last four decades. One of the major challenges, however, remaining is reproducible synthesis employing a variety of precursors. In the case of synthesis of CdSe, often reagents are challenging to handle in terms of their stability and toxicity. Yet, this semiconductor material alone has been studied by many as a model compound semiconductor in terms of quantum dots and the same has been extended to magic-sized nanoclusters in view of the great potential as white light emitting materials. The present review discusses some of the aspects related to magic-sized CdSe nanoclusters to boost the understanding and possibility of their application in photonics and electronics.

Progress of hybrid nanocomposite materials for thermoelectric applications

Abstract: Presently, the energy crisis and environmental burden have become two major problems due to the mismanagement of thermal power Accordingly, the tremendous amount of waste heat from various energy sectors can be utilized by thermoelectric generators as a green energy source Generally, thermoelectric generators (TEGs) exhibit enormous potential for converting waste heat to electricity without involving any mechanical vibrations and noises However, they suffer from the disadvantages of expensive manufacturing techniques, low reliability, and scarce availability of conventional thermoelectric materials Therefore, there has been significant interest from researchers in developing advanced new thermoelectric materials (TEMs) Recently, the promising thermoelectric properties of organic and inorganic nanomaterial-based hybrid nanocomposites have gained popularity among researchers The grafting of conducting organic and inorganic thermoelectric nanoparticles on graphene/CNT matrices combines the advantages of both inorganic and organic materials The present review comprehensively presents new hybrid nanocomposite-based TEMs used specifically for wearable TEGs To demonstrate the performance requirement of these TEGs, we discuss their material synthesis methods, fabrication techniques and possible mechanisms in detail For comparison, a few traditional TEMs are also reported with the addition of current and potential advanced general applications of TE materials in the form of rigid and wearable devices

Synthesis of biologically active silver nanoparticles by use of N-containing compounds : Dual role of semicarbazones

Abstract: In the current work, the synthesis of silver nanoparticles is carried out by the use of semicarbazones and the potential of such N-compounds is presented as useful reagents for nanotechnology. Nanochemistry of semicrbazones have been practiced in the present work to establish simple and convenient protocol for first use of semicarbazones in the synthesis of silver nanoparticles. It is believed that the chosen semicarbazones played dual role i.e. they acted as reducing agent as well as capping agent. The synthesized silver nanoparticles were investigated by UV/Visible and FTIR spectroscopy, XRD, SEM, TGA, and TEM. The UV/Vis studies revealed surface plasmon resonance (SPR), a characteristic phenomenon in silver nano-particles between 400-450 nm. XRD measurement confirmed face centered cubic (FCC) silver with particle diameter in the range of 20-30 nm. The TEM shows particle size of < 10 nm. The antimicrobial activity of semicarbazone synthesized silver nanoparticles were examined by well-diffusion method against the fungi Aspergillus Niger, Gram-negative bacteria Escherichia coli, and Gram-positive bacteria Bacillus Subtilis. It was found that all the samples showed enhanced antimicrobial properties in comparison to their parent semicarbazones.