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Duraivel, Malarkodi,Nagappan, Saravanan,Balamuralitharan, B.,Selvam, S.,Karthick, S. N.,Prabakar, K.,Ha, Chang-Sik,Kim, Hee-Je The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.13
<P>In this work, we report the synthesis of sulfur-doped reduced graphene oxide (S-rGO) using sodium borohydride (NaBH4) and sodium sulfide (Na2S) by a facile one-pot approach <I>via</I> refluxing in deionised water. The undoped rGO chemical structure is partially reduced by NaBH4, whereas the addition of a small amount of Na2S with NaBH4 resulted in a better reduction of rGO. XPS analysis confirmed the successful doping of sulfur and Raman spectroscopy verified the increased defect density. The S-rGO electrode exhibits good power density (3202 W kg<SUP>−1</SUP>) with increased specific capacitance (392 F g<SUP>−1</SUP>) and cyclic stability (91%, 2000 cycles) in 1 M Na2SO4 aqueous electrolyte. The obtained results suggest that the simple tuning of the graphene oxide structure using Na2S with NaBH4 enhances the above properties. Moreover, this method is facile and allows the easy reproduction of bulk quantities of materials for use in commercial applications.</P>
Titanium dioxide paste preparation for dye sensitized solar cell using hydrothermal technique
S.N. Karthick 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.S1
The TiO2 pastes were prepared from commercial P25 titanium oxide powder (sample A) and titanium isopropoxide (sample B) using a hydrothermal technique. The pastes were coated on FTO glass plate and sintered at 500 ο C for 30 minutes. The coated films were characterized by XRD, FTIR, SEM, TEM, UV and IV studies. XRD results confirmed that both of anatase and rutile phase were found in the film from sample A but only anatase phase were formed from sample B. The lattice parameters of sample A is a = 3.789 Å and c = 9.526 Å and those of sample B is a = 3.786 Å and c = 9.508 Å. FT-IR studies showed that there is no precursor residue present in both the sample after sintering. The UV-Vis spectrum indicates the amount of dye adsorbed on TiO2 particle. The conversion efficiency, short circuit current (Jsc), open circuit voltage (Voc) is 5.7%, 11.34 mA/cm2 and 0.7111 V, respectively, which is high for sample B compared to sample A.
Selvam, S.,Balamuralitharan, B.,Karthick, S. N.,Hemalatha, K. V.,Prabakar, K.,Kim, Hee-Je The Royal Society of Chemistry 2016 Analytical methods Vol.8 No.44
<▼1><▼1><P>A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance.</P></▼1><▼2><P>A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance. This typical composite electrode was prepared from electrochemically reduced e-rGO followed by the addition of β-cyclodextrin and MnO2 from Mn(CH3COOH)2·4H2O on FTO surfaces. The composite material is indexed to the corresponding crystalline phase of MnO2 in the XRD investigation and Mn 3p, Mn 2p, C 1s, and O 1s signals were identified from XPS analysis. The cyclic voltammetry study reveals that the potential of the caffeine samples and the square wave voltammetry peak currents indicate an increasing trend for caffeine oxidation. The sensor expressed a sensitivity of 0.187 μA cm<SUP>2</SUP> μM<SUP>−1</SUP> with a linear range of 10–550 μM (<I>n</I> = 3.12). The corresponding supercapacitor also exhibited a specific capacitance of 352 F g<SUP>−1</SUP> and it showed a very good life time from a long term cyclic test. The proposed ternary composite electrodes may be suitable electrodes for self-powered sensor devices.</P></▼2></▼1>
Selvam, S.,Balamuralitharan, B.,Jegatheeswaran, S.,Kim, M. Y.,Karthick, S. N.,AnandhaRaj, J.,Boomi, P.,Sundrarajan, M.,Prabakar, K.,Kim, H. J. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.4
<P>Electrolyte-imprinted and copper crosslinked hybrid flexible electrodes have been considered as long-term stability supercapacitors. Graphene oxide, chitosan and copper (copper chloride) were crosslinked under ionic liquid medium using a hydrothermal technique. The fabricated flexible supercapacitor exhibits a maximum 356 F g(-1) specific capacitance and possesses extreme cyclic stability up to 200 000 cycles.</P>
Selvam, S.,Balamuralitharan, B.,Karthick, S. N.,Savariraj, A. Dennyson,Hemalatha, K. V.,Kim, Soo-Kyoung,Kim, Hee-Je The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.19
<▼1><P>A novel sulfated β-cyclodextrin/PVP/MnCO3 composite has been synthesized for a parallel-connected supercapacitor and dye-sensitized solar cell (counter electrode).</P></▼1><▼2><P>A novel sulfated β-cyclodextrin/PVP/MnCO3 composite has been synthesized for a parallel-connected supercapacitor and dye-sensitized solar cell (counter electrode). β-Cyclodextrin has sulfonated, thermally cross-linked with PVP, and incorporated with MnCO3 nanoparticles. The composite electrode exhibited 202.6 F g<SUP>−1</SUP> capacitance, 197.96 W h kg<SUP>−1</SUP> energy density, 5.57% <I>η</I> (DSSC) and 70% performance up to 200 °C with a [BMI][TFSI] electrolyte.</P></▼2>
La-doped ZnO nanoflower as photocatalyst for methylene blue dye degradation under UV irradiation
Hemalatha, P.,Karthick, S. N.,Hemalatha, K. V.,Yi, M.,Kim, H. J.,Alagar, M. Springer Science + Business Media 2016 Journal of materials science Materials in electron Vol.27 No.3
<P>Lanthanum doped ZnO flower-like structured nanoparticles were synthesized through microwave assisted sol-gel technique. X-ray diffraction, scanning electron microscopy, transmission electron microscopy analysis confirmed the size, structural morphology and successful compound formation of the samples. The band gap was calculated from Tauc's plot using UV-Vis spectroscopy data. Lanthanum doped ZnO nanoparticles were used for the photocatalytic degradation of methylene blue dye under UV light irradiation. Compared to pure ZnO sample, La-doped samples exhibited higher photocatalytic dye degradation under UV light irradiation with short time duration. Among the different amounts of dopant, 3 mol% La-doped ZnO nano rods showed the highest degradation with short time UV light irradiation (60 min). Other factors such as particle size, morphology and defects also affect the photocatalytic activity. In our study, the main factor that influence photocatalytic activity is the separation of photo induced electron-hole pair due to defects formation in the sample. The 3 mol% sample has the appropriate electron-hole separation due to defects compared to pure ZnO. The influence of defects on the photocatalytic activity of all samples has been revealed using photoluminescence spectroscopy analysis. Furthermore, the effect of various operational parameters such as photocatalyst quantity, dye concentration and dopant concentrations were also optimized.</P>