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Zhu P.,National University of Singapore | Reddy M.V.,National University of Singapore | Wu Y.,National University of Singapore | Peng S.,National University of Singapore | And 6 more authors.
Chemical Communications | Year: 2012

Mesoporous SnO 2 agglomerates with hierarchical structures and a high surface area were fabricated through a molten salt method. The SnO 2 demonstrated high photoelectric conversion efficiencies of 3.05% and 6.23% (with TiCl 4 treatment) in dye-sensitized solar cells, which are attributed to its dual functionality of providing high dye-loading and efficient light scattering. © 2012 The Royal Society of Chemistry.


Ranjusha R.,Amrita Center for Nanosciences and Molecular Medicine | Sreekumaran Nair A.,Amrita Center for Nanosciences and Molecular Medicine | Ramakrishna S.,National University of Singapore | Anjali P.,Amrita Center for Nanosciences and Molecular Medicine | And 6 more authors.
Journal of Materials Chemistry | Year: 2012

The present study demonstrates a novel approach by which titanium foils coated with MnO2 nanowires can be processed into a high surface area electrode for rechargeable energy storage applications. A detailed study has been performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes impact the cyclic and capacitive behavior of the electrode. These nanowires were synthesized hydrothermally and exhibited an aspect ratio in the order of 102. BET analysis revealed that these MnO2 nanowires show a high surface area of 44 m2 g -1. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the capacitance, internal resistance and the surface morphology has been deduced and explained on the basis of relative contributions from the faradic properties of the MnO2 in different electrolytes. Depending on the type of surface morphology incorporated, these thin film nanowire electrodes exhibited specific mass capacitance value as high as 1050 F g-1 and 750 F g-1 measured from cyclic voltammetry and charge-discharge curves respectively. It has been shown that electrodes based on such nanowires can allow significant room for improvement in the cyclic stability of a hybrid supercapacitor/battery system. Further, a working model supercapacitor in cylindrical form is also shown exhibiting a capacitance of 10 F. © 2012 The Royal Society of Chemistry.


Ranjusha R.,Amrita Center for Nanosciences and Molecular Medicine | Prathibha V.,Amrita Center for Nanosciences and Molecular Medicine | Ramakrishna S.,National University of Singapore | Sreekumaran Nair A.,Amrita Center for Nanosciences and Molecular Medicine | And 7 more authors.
Scripta Materialia | Year: 2013

The present study investigates a novel approach by which MnO2 nanoparticle and camphoric carbon nanobead blends are coated on Ti-foils for rechargeable energy storage applications. Depending on the amount of nanocarbon blended onto the MnO2 nanoflake system, these thin film nanocomposite electrodes can exhibit a specific mass capacitance value as high as 1020 F g-1. It has been shown that electrodes based on such a composite system can allow significant room for improvement in the cyclic stability of a rechargeable electrode system.© 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Lekha P.,Amrita Center for Nanosciences and Molecular Medicine | Balakrishnan A.,Amrita Center for Nanosciences and Molecular Medicine | Subramanian K.R.V.,Amrita Center for Nanosciences and Molecular Medicine | Nair S.V.,Amrita Center for Nanosciences and Molecular Medicine
Materials Chemistry and Physics | Year: 2013

In this present study, we demonstrate the size dependent charge transfer from CdTe quantum dots (QDs) into TiO2 substrate and relate this charge transfer to the actual behavior of a CdTe sensitized solar cell. CdTe QDs was synthesized using mercaptopropionic acid as the capping agent. The conduction band offset for TiO2 and CdTe QDs indicates thermodynamically favorable band edge positions for smaller QDs for the electron-transfer at the QD-TiO2 interface. Time-resolved emission studies were carried out for CdTe QD on glass and CdTe QD on TiO2 substrates. Results on the quenching of QD luminescence, which relates to the transfer kinetics of electrons from the QD to the TiO2 film, showed that at the smaller QD sizes the transfer kinetics are much more rapid than at the larger sizes. I-V characteristics of quantum dot sensitized solar cells (QDSSC) with different sized QDs were also investigated indicating higher current densities at smaller QD sizes consistent with the charge transfer results. The maximum injection rate constant and photocurrent were obtained for 2.5 nm CdTe QDs. We have been able to construct a solar cell with reasonable characteristics (Voc = 0.8 V, Jsc = 1 mA cm-2, FF = 60%, η = 0.5%)© 2013 Elsevier B.V. All rights reserved.


Mini P.A.,Amrita Center for Nanosciences and Molecular Medicine | Balakrishnan A.,Amrita Center for Nanosciences and Molecular Medicine | Nair S.V.,Amrita Center for Nanosciences and Molecular Medicine | Subramanian K.R.V.,Amrita Center for Nanosciences and Molecular Medicine
Chemical Communications | Year: 2011

We report on the development and characterization of high performance supercapacitor electrodes synthesized using electrophoretic deposition of graphene, upon which the poly(pyrrole)-layer was electropolymerised. The highly capacitive electrode had a specific capacitance of 1510 F g-1, area capacitance of 151 mF cm-2 and volume capacitance of 151 F cm -3 at 10 mV s-1. © 2011 The Royal Society of Chemistry.

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