Structural and magnetic property studies on low temperature chemically synthesised one-dimensional Zn1−xNixO nanorods

Mohan Kumar, G.,Ilanchezhiyan, P.,Poongothai, S.,Park, Jinsub,Jayavel, R. Springer-Verlag 2014 Journal of materials science Materials in electron Vol.25 No.3

Solution processed n-In2O3nanostructures for organic-inorganic hybrid p-n junctions

Kumar, G. Mohan,Kumar, A. Madhan,Ilanchezhiyan, P.,Kang, T. W. The Royal Society of Chemistry 2014 Nanoscale Vol.6 No.19

<P>Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 1020 cm-3 were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.</P>

Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

Mohan Kumar, G.,Ilanchezhiyan, P.,Madhan Kumar, A.,Yuldashev, Sh.U.,Kang, T.W. Elsevier 2016 Chemical physics letters Vol.649 No.-

<P>A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current-voltage characteristics on the fabricated PPy/A1 doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications. (C) 2016 Elsevier B.V. All rights reserved.</P>

High performance photodiodes based on chemically processed Cu doped SnS₂ nanoflakes

Mohan Kumar, G.,Xiao, Fu,Ilanchezhiyan, P.,Yuldashev, Sh.,Madhan Kumar, A.,Cho, H.D.,Lee, D.J.,Kang, T.W. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.455 No.-

<P><B>Abstract</B></P> <P>In this work, Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized through a simple hydrothermal method. The influence of Cu doping on the structural, optical and electrical properties of SnS<SUB>2</SUB> were investigated in detail. Optical properties explores the Cu doping in SnS<SUB>2</SUB> crystal lattice to result with a red-shift in absorption spectrum, which benefits visible-light absorption. Photodiodes were further fabricated by spin coating Cu doped SnS<SUB>2</SUB> nanoflakes on p-type silicon (Si). Electrical and photoelectrical parameters of Cu doped SnS<SUB>2</SUB> nanoflakes were determined by studying their impedance and current–voltage (I–V) characteristics, respectively. The diodes were found to exhibit excellent rectifying behavior and good sensitivity on par to pristine photodiodes. Impedance results identified the resistance of device to reduce considerably on Cu doping. The enhanced photoelectrical properties of the heterojunctions has been ascribed to Cu ions, which act as effective dopant and contribute to the varied carrier concentration in SnS<SUB>2</SUB>. Finally the obtained results suggest the potential of Cu-doped SnS<SUB>2</SUB> for application in photodetection and sensors applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized in hexagonal phase. </LI> <LI> Nature of charge carriers/carrier density was determined using Mott-Schottky plots. </LI> <LI> Photodiode based on Cu doped SnS<SUB>2</SUB> nanoflakes were fabricated on p-Si substrate. </LI> <LI> Photodiode revealed improved photocurrent and responsitivity values under illumination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrochemical studies on two-dimensional ZnInO nanoplates for organic–inorganic hybrid photodiode related applications

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T.W. Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.619 No.-

<P><B>Abstract</B></P> <P>An ultra low cost route has been established to fabricate organic–inorganic hybrid <I>p</I> <I>–</I> <I>n</I> junctions <I>via</I> chemical <I>in-situ</I> polymerization of organic monomers on traditionally drop casted inorganic deposits. In this regard, ZnInO nanoplate-like structures were synthesized through a facile solution based chemical approach and their structural property was studied using X-ray diffraction patterns. The nature of charge carriers and donor density in ZnInO made electrodes were studied using electrochemical impedance spectroscopy. The dissemination of polymer matrices on the ZnInO nanoplates was examined through scanning electron microscopy. The current–voltage characteristics obtained across the polypyrrole/ZnInO made hybrid structures revealed an improved rectifying behaviour under illuminated conditions. The mechanism behind the drastic decrease in resistance values that substantiates the improved electron transfer characteristics across the organic–inorganic structures was studied through cyclic voltammetric measurements.</P>

Evidencing enhanced charge-transfer with superior photocatalytic degradation and photoelectrochemical water splitting in Mg modified few-layered SnS₂

Mohan Kumar, G.,Cho, H.D.,Ilanchezhiyan, P.,Siva, C.,Ganesh, V.,Yuldashev, Sh.,Madhan Kumar, A.,Kang, T.W. Elsevier 2019 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.540 No.-

<P><B>Abstract</B></P> <P>Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS<SUB>2</SUB>) for potential employment in energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS<SUB>2</SUB> to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB>. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS<SUB>2</SUB> nanosheets. The value of rate constants obtained for the Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets was found to be 1.4 times higher than that of pristine SnS<SUB>2</SUB>. Finally, the results obtained through the present study projects the huge potential of layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets for future multifunctional applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of polypyrrole/ZnO nanowires based organic–inorganic hybrid p-n junctions

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T. W. Springer Science + Business Media 2015 Journal of materials science Materials in electron Vol.26 No.4

Effect of ethylenediamine tetra acetic acid additive on the nucleation kinetics and growth aspects of L-arginine phosphate single crystals

Kumar, R.Mohan,Babu, D.Rajan,Ravi, G.,Jayavel, R. The Korea Association of Crystal Growth 2003 韓國結晶成長學會誌 Vol.13 No.4

Pure and Ethylenediaminetetraacetic acid (EDTA) doped L-arginine phosphate (LAP) single crystals were grown from the aqueous solution by temperature lowering method. The effect of EDTA additive on the solubility and metastable zone width of LAP solution has been investigated. Addition of EDTA has enhanced the metastable zone width of LAP and hence bulk crystals could be grown. The growth rate along the [100] direction increases with EDTA additive. Powder X-ray diffraction and FTIR studies reveal the absence of EDTA in the lattice of LAP, This reveals that the addition of EDTA to LAP doesn't influence the crystallinity. However, the transmittance and NLO properties significantly increase with EDTA additive and hence bulk LAP crystals are useful for laser fusion experiments.

A hybrid method for fundamental heart sound segmentation using group-sparsity denoising and variational mode decomposition

V. G. Sujadevi,Neethu Mohan,S. Sachin Kumar,S. Akshay,K. P. Soman 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.4

Segmentation of fundamental heart sounds–S1 and S2 is important for automated monitoring of cardiac activity includingdiagnosis of the heart diseases. This pa-per proposes a novel hybrid method for S1 and S2 heart sound segmentation usinggroup sparsity denoising and variation mode decomposition (VMD) technique. In the proposed method, the measured phonocardiogram(PCG) signals are denoised using group sparsity algorithm by exploiting the group sparse (GS) property ofPCG signals. The denoised GS-PCG signals are then decomposed into subsequent modes with specifi c spectral characteristicsusing VMD algorithm. The appropriate mode for further processing is selected based on mode central frequencies and modeenergy. It is then followed by the extraction of Hilbert envelope (HEnv) and a thresholding on the selected mode to segmentS1 and S2 heart sounds. The performance advantage of the proposed method is verifi ed using PCG signals from benchmarkdatabases namely eGeneralMedical, Littmann, Washington, and Michigan. The proposed hybrid algorithm has achieved asensitivity of 100%, positive predictivity of 98%, accuracy of 98% and detection error rate of 1.5%. The promising resultsobtained suggest that proposed approach can be considered for automated heart sound segmentation.

Computational design of mould sprue for injection moulding thermoplastics

Lakkannan, Muralidhar,Mohan Kumar, G.C.,Kadoli, Ravikiran Society for Computational Design and Engineering 2016 Journal of computational design and engineering Vol.3 No.1

To injection mould polymers, designing mould is a key task involving several critical decisions with direct implications to yield quality, productivity and frugality. One prominent decision among them is specifying sprue-bush conduit expansion as it significantly influences overall injection moulding; abstruseness anguish in its design criteria deceives direct determination. Intuitively designers decide it wisely and then exasperate by optimising or manipulating processing parameters. To overwhelm that anomaly this research aims at proposing an ideal design criteria holistically for all polymeric materials also tend as a functional assessment metric towards perfection i.e., criteria to specify sprue conduit size before mould development. Accordingly, a priori analytical criterion was deduced quantitatively as expansion ratio from ubiquitous empirical relationships specifically a.k.a an exclusive expansion angle imperatively configured for injectant properties. Its computational intelligence advantage was leveraged to augment functionality of perfectly injecting into an impression gap, while synchronising both injector capacity and desired moulding features. For comprehensiveness, it was continuously sensitised over infinite scale as an explicit factor dependent on in-situ spatio-temporal injectant state perplexity with discrete slope and altitude for each polymeric character. In which congregant ranges of apparent viscosity and shear thinning index were conceived to characteristically assort most thermoplastics. Thereon results accorded aggressive conduit expansion widening for viscous incrust, while a very aggressive narrowing for shear thinning encrust; among them apparent viscosity had relative dominance. This important rationale would certainly form a priori design basis as well diagnose filling issues causing several defects. Like this the proposed generic design criteria, being simple would immensely benefit mould designers besides serve as an inexpensive preventive cliché to moulders. Its adaption ease to practice manifests a hope of injection moulding extremely alluring polymers. Therefore, we concluded that appreciating injectant's polymeric character to design exclusive sprue bush offers a definite a priori advantage.