Faculty Publications
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Item Synthesis, Characterization and Performance Studies of a New Metal-Free Organic Sensitizer for DSSC application(Elsevier Ltd, 2018) Naik, P.; Babu, D.D.; Su, R.; El-Shafei, A.; Vasudeva Adhikari, A.V.In this present work we report, design, synthesis and performance studies of a new metal-free organic dye (N, N'-PABA) based on N,N-dimethyl-4-vinyl aniline carrying 4-amino benzoic acid as acceptor, as sensitizers for sensitizing photoanode (TiO2). In the sensitizers, N,N-dimethylaniline ring acts as anelectron donorwhile para amino benzoic acid function as electron acceptor/anchoring units. It was synthesized via condensation reaction starting from simple 4-(N,N-dimethyl amino)benzaldehyde and their structures were confirmed using spectral techniques like FTIR, 1HNMR, 13CNMR, MS and elemental analysis. Further, it was subjected to electrochemical and optical characterization in order to evaluate their band gap and absorption/emission behavior. Further, DFT studies were performed using turbo mole V6.6 software package to evaluate their optimized geometry and FMO levels. Finally, DSSC devices were fabricated using this dye under simulated solar radiation AM1.5G and result revealed that it shows a conversion efficiency of 1%. © 2018 Elsevier Ltd.Item Molecular Engineering of a New Organic Chromophore with D-Ï€-A Architecture for Dye-Sensitized Solar Cells(Elsevier Ltd, 2018) Naik, P.; Vasudeva Adhikari, A.V.Herein, we report design and synthesis of a new metal-free organic dye N1 derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl) acrylonitrile scaffold. In this design, the electron rich carbazole unit is connected to rhodanine-3-acetic acid via cyano vinyl thiophene as Ï€-spacer. Its molecular structure was confirmed by FTIR, NMR, Mass spectral and elemental analyses. The dye was subjected to optical and electrochemical studies in order to investigate their absorption/emission behaviour as well as HOMO/LUMO energies. The DFT studies were performed using Turbomole 7.1V software and the results indicated the existence of proper charge separation between its HOMO and LUMO energy levels. © 2018 Elsevier Ltd. All rights reserved.Item Effect of 1,2,3benzotriazole on the corrosion of aged 18Ni250 grade Maraging steel in Phosphoric acid solution(Institute of Physics Publishing helen.craven@iop.org, 2018) Naik, P.; Nayak, J.; Girish, L.V.; Somashekhar, T.M.; Bhanuprakash, S.H.; Rahul, S.The 18 Ni 250 grade maraging steel is a potential high strength steel for advanced technologies such as aerospace, nuclear, and sporting goods. Phosphoric acid and Nitric acid solutions are used in pickling of delicate and precision items where re-rusting after pickling has to be avoided. The present work addresses the study of corrosion behaviour and inhibition using 1,2,3 benzotriazole of aged 18 Ni 250 grade maraging steel in phosphoric acid medium at higher concentration by Potentiodynamic Polarization Technique. The corrosion rates were determined in 1M, 1.5M and 2M by Tafel extrapolation technique in the temperature range 300C-500C with different concentrations of inhibitor. The results indicate that the corrosion rate increases with increase in acid concentration and temperature.Inhibition efficiency of 1,2,3benzotriazolewas found to increase with the increase in 1,2,3 benzotriazole concentration and decrease with the increase in temperature.The activation energy Ea and other thermodynamic parameters (ΔG,ΔH# andΔS#) have been evaluated and discussed. The standard free energy of adsorptionΔGads values indicates that the adsorption is of mixed type. Scanning electron microscopy (SEM) study confirmed the formation of an adsorbed protective film on the metal surface. © Published under licence by IOP Publishing Ltd.Item One-step simple method for the determination of palladium using 3-acetyl2-thiohydantoin as a releasing agent(2009) Karthikeyan, J.; Naik, P.; Nityananda Shetty, A.N.A simple, rapid and accurate complexometric method for the determination of palladium(II) is proposed, based on the selective masking property of 3-acetyl-2-thiohydantoin (ATH) towards palladium(II). In the presence of diverse metal ions, palladium(II) is complexed with excess of EDTA and the surplus EDTA is back titrated with standard lead nitrate solution at pH 5-6 (acetic acid - sodium acetate buffer) using xylenol orange as indicator. An excess of a 0.5% solution of ATH is then added to displace EDTA from Pd(II) - EDTA complex. The released EDTA is titrated with the same standard lead nitrate solution as before. Reproducible and accurate results are obtained in the concentration range 0.35-11.00 mg of palladium with relative error of ±0.46% and coefficient of variation not exceeding 0.36%. The effects of diverse ions are studied. The method is used for the determination of palladium in alloys, hydrogenation catalyst and complexes with a fair degree of accuracy.Item Carbon-carbon composites by preformed yarn method(2011) Naik, P.; Neelakantha, N.V.; Surendranathan, A.O.; Jayaraju, T.The conventional techniques of manufacturing carbon-carbon(C/C) composites have reportedly encountered problems because the resulting C/C composites exhibit non-uniform properties such as bending strength and density. A novel method of manufacturing C/C composites by preformed yarns (PY) is used. The matrix powder consists of coke powders and the binder. The preformed yarn contains the matrix powders inside the carbon fiber bundle and coated on circumference with nylon-6 polymer. This preformed yarn is then chopped and hot pressed at about 600°C to get bars and pellets. These are again heat treated at 1500°C and further impregnated by one more pitch cycle, again heat treated at 2200°C. The tests for hardness, compression strength, Creep strength, resistance to oxidation, and fracture toughness are conducted on these pellets and bars. The micostructural analysis in SEM is done. These tests reveal that the properties obtained from PY method are superior to the properties obtained from any other conventional method.Item Single step determination of platinum(IV) in alloys, catalysts, complexes, environmental and pharmaceutical samples using p-[N,N-bis(2-chloroethyl)amino] benzaldehyde thiosemicarbazone(Indian Chemical Society, 2013) Karthikeyan, J.; Naik, P.; Nityananda Shetty, A.N.p-[N,N-Bis(2-chloroethyl)amino]benzaldehyde thiosemicarbazone is proposed as an analytical reagent for the spectrophotometric determination of platinum(IV). The reagent forms yellow colored complex with platinum(IV) in the concentration range of 0.016-0.080 M hydrochloric acid medium. Beer's law is obeyed in the concentration range up to 12.48 ?g cm-3. The optimum concentration range for minimum photometric error as determined by Ringbom's plot method is 3.12-10.92 ?g cm-3. The yellowish Pt IV-reagent complex shows a maximum absorbance at 390 nm, with molar absorptivity of 2.05 × 104 dm3 mol-1 cm-1 and Sandell's sensitivity of the complex from Beer's data, for D = 0.001, is 0.012 ?g cm-2. The composition of the Pt IV-CEABT complex is found to be 1:2 (M:L) by Job's method and by mole-ratio method. The relative error and coefficient of variation (n = 6) of the method does not exceed ±0.80% and ±0.32% respectively. The interference of various cations and anions in the method were studied. The proposed method was successfully used for the determination of PtIV in alloys, catalysts, complexes, environmental and pharmaceutical samples. The method is rapid as the PtIV-CEABT complex is soluble in water-ethanol-DMF medium and not requiring any time consuming extraction method for the complex.Item Determination of fracture toughness and fatigue crack growth rate using circumferentially cracked round bar specimens of Al2014T651(Elsevier Masson SAS infos@masson.fr 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2015) Neelakantha, V.L.; Jayaraju, T.; Naik, P.; Kumar K, D.; Rajashekhar, C.R.; Kumar, M.Fracture toughness (KIC) and fatigue crack growth rate (FCGR) are the important material properties in fracture mechanics. ASTM-E399 and ASTM-E647 are the standards for determination of KIC and FCGR of metallic materials. These standards recommend the use of compact tension (CT) or single edge notched bend (SENB) test specimens. Literature review indicates that CT or SENB specimens are complex in nature, difficult to manufacture, require typical fixtures for loading during experimentation and the test procedures using CT or SENB are time consuming and cumbersome. An alternate specimen geometry which can overcome the above said drawbacks is needed by the industry which can be used as standard test specimen geometry. This research work explains use of circumferentially cracked round bar (CCRB) specimens of high strength Al2014T651 alloy for determination of KIC and FCGR.The pre-cracked round bar specimen was loaded in tensile in a universal testing machine and pulled till failure. Using suitable stress intensity factor equations the fracture toughness can be calculated. In case of crack growth test, the pre-cracked round bar specimen is allowed to rotate under fatigue load. The ratio of length of crack propagated to the number of cycles to failure was the crack growth rate. The SEM analysis of fractured surfaces was also done.The results are comparable with the values reported in the literature obtained by using standard test specimens. There are numerous advantages of using round bar specimen in KIC and FCGR tests. It is concluded that, the methodology of determination of fracture toughness and fatigue crack growth rate using CCRB specimens is relatively simple, reliable, fast and economical. CCRB specimen may be recommended as a standard test specimen for fracture toughness as well as crack growth tests. © 2015 Elsevier Masson SAS. All rights reserved.Item Friction and dry sliding wear of bismaleimide filled with carbon nanotubes(Taylor and Francis Ltd. maney@maney.co.uk, 2016) Kurahatti, R.V.; Surendranathan, A.O.; Mordina, B.; Naik, P.; Auradi, V.Three types of bismaleimide–carbon nanotubes (CNTs) nanocomposites were fabricated using two types of original multiwalled CNTs with different diameters and one amide functionalized CNTs. The influence of diameter, content and functionalization of CNTs on the flexural and dry sliding wear behaviour were measured with universal testing machine and pin-on-disc wear apparatus. The experimental results indicated that at 1.5 wt-%, the bismaleimide-functionalized MWCNTs exhibited highest flexural strength of 156 MPa which is increased by 164% as compared to the neat matrix, and lowest specific wear rate of 1.8 × 10?4 mm3 N?1 m?1 which is decreased by 90% as compared to the neat matrix. This was attributed to the dispersion of CNTs in the matrix and the filler-matrix adhesion and internal strength of the composite. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Item New carbazole based metal-free organic dyes with D-?-A-?-A architecture for DSSCs: Synthesis, theoretical and cell performance studies(Elsevier Ltd, 2017) Naik, P.; Elmorsy, M.R.; Su, R.; Babu, D.D.; El-Shafei, A.; Vasudeva Adhikari, A.V.Herein we report the design, synthesis and photovoltaic performance studies of three new D-?-A-?-A architectured organic chromophores (N1-3) derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl) acrylonitrile scaffold. In the new design, the electron rich carbazole unit is connected to three different electron withdrawing/anchoring species, viz. cyano acetic acid, rhodanine-3-acetic acid and barbituric acid via cyano vinyl thiophene as ?-spacer. Newly synthesized dyes were characterized by spectral, photophysical and electrochemical analyses. Their optical band-gap, GSOP and ESOP values, as calculated from the optical and CV studies were found to be in the range of 2.12–2.21, ?5.52 to ?5.43 and ?5.40 to ?3.25 eV respectively. The DFT and TD-DFT studies were performed using Turbomole 7.1V software and the results indicated the existence of proper charge separation between HOMO and LUMO levels of the dyes. Also, the results revealed good matching of theoretically generated optical spectral data with the experimental values. Finally, DSSC devices were fabricated using these three dyes and the dye N1 containing cyanoacetic acid as an acceptor unit showed better photo conversion efficiency (?) of 3.55% than the other two dyes. It's JSC, VOC, and IPCE parameters were shown to be 9.06 mA cm?2, 0.577 V and 48%, respectively. The obtained EIS data and electron lifetimes of N1–3 sensitized devices are well in accordance with experimental photovoltaic parameters. © 2017 Elsevier LtdItem Exploring the application of new carbazole based dyes as effective p-type photosensitizers in dye-sensitized solar cells(Elsevier Ltd, 2017) Naik, P.; Planchat, A.; Pellegrin, Y.; Odobel, F.; Vasudeva Adhikari, A.V.Herein, we report the design and the synthesis of three new D-A type metal-free carbazole based dyes (C1–3) as effective photosensitizers for p-type DSSCs. In this new design, the electron rich carboxy substituted carbazole unit has been attached to three different electron withdrawing species, viz. N,N-dimethyl barbituric acid, N,N-diethyl thiobarbituric acid and N-ethyl rhodanine. They were well-characterized by spectral, photophysical and electrochemical analyses. Further, their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of structures of C1–3 on their photovoltaic performances. Further, the photovoltaic performance of C1–3 was determined along with the standard dye P1 and their PCE values were found to be in the order of P1 (0.047%) > C2 (0.040%) > C1 (0.016%) > C3 (0.001%). Interestingly, the NiO based p-type DSSC fabricated with C2 carrying electron withdrawing N,N-diethyl thiobarbituric acid displayed VOC as 59 ± 4 mV and FF as 29 ± 1%, which are higher than that of benchmark reference P1. This is attributed to the highest light harvesting ability, the greatest regeneration driving force and the lowest interfacial charge recombination of C2 among the tested dyes. Conclusively, the results showcase the potential of carbazole based D-A type sensitizers in the development of efficient p-type DSSCs. © 2017 Elsevier Ltd