@article { ISI:000291715300005, title = {Electrochemical unzipping of multi-walled carbon nanotubes for facile synthesis of high-quality graphene nanoribbons}, journal = {Journal of the American Chemical Society}, volume = {133}, number = {12}, year = {2011}, month = {MAR}, pages = {4168-4171}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Here we report a remarkable transformation of carbon nanotubes (CNTs) to nanoribbons composed of a few layers of graphene by a two-step electrochemical approach. This consists of the oxidation of CNTs at controlled potential, followed by reduction to form graphene nanoribbons (GNRs) having smooth edges and fewer defects, as evidenced by multiple characterization techniques, including Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. This type of {\textquoteleft}{\textquoteleft}unzipping{\textquoteright}{\textquoteright} of CNTs (single-walled, multi-walled) in the presence of an interfacial electric field provides unique advantages with respect to the orientation of CNTs, which might make possible the production of GNRs with controlled widths and fewer defects.

}, issn = {0002-7863}, doi = {10.1021/ja1101739}, author = {Shinde, Dhanraj B. and Debgupta, Joyashish and Kushwaha, Ajay and Aslam, Mohammed and Pillai, Vijayamohanan K.} } @article { ISI:000308879000041, title = {Electrochemical preparation of luminescent graphene quantum dots from multiwalled carbon nanotubes}, journal = {Chemistry-A European Journal}, volume = {18}, number = {39}, year = {2012}, month = {SEP}, pages = {12522-12528}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Green luminescent, graphene quantum dots (GQDs) with a uniform size of 3, 5, and 8.2(+/- 0.3) nm in diameter were prepared electrochemically from MWCNTs in propylene carbonate by using LiClO4 at 90?degrees C, whereas similar particles of 23(+/- 2) nm were obtained at 30?degrees C under identical conditions. Both these sets of GQDs displayed a remarkable quantum efficiency of 6.3 and 5.1?\%, respectively. This method offers a novel strategy to synthesise size-tunable GQDs as evidenced by multiple characterisation techniques like transmission and scanning electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray diffraction (XRD). Photoluminescence of these GQDs can be tailored by size variation through a systematic change in key process parameters, like diameter of carbon nanotube, electric field, concentration of supporting electrolyte and temperature. GQDs are promising candidates for a variety of applications, such as biomarkers, nanoelectronic devices and chemosensors due to their unique features, like high photostability, biocompatibility, nontoxicity and tunable solubility in water.

}, keywords = {electrochemical synthesis, graphene, Nanostructures, photoluminescence, quantum dots}, issn = {0947-6539}, doi = {10.1002/chem.201201043}, author = {Shinde, Dhanraj B. and Pillai, Vijayamohanan K.} } @article { ISI:000315209900016, title = {Electrochemical resolution of multiple redox events for graphene quantum dots}, journal = {Angewandte Chemie-International Edition}, volume = {52}, number = {9}, year = {2013}, month = {JAN}, pages = {2482-2485}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {charging energy, differential pulse voltammetry, graphene, quantum dots, single-electron transfer}, issn = {1433-7851}, doi = {10.1002/anie.201208904}, author = {Shinde, Dhanraj B. and Pillai, Vijayamohanan K.} } @article { ISI:000353831200020, title = {Electrochemical preparation of nitrogen-doped graphene quantum dots and their size-dependent electrocatalytic activity for oxygen reduction}, journal = {Bulletin of Materials Science}, volume = {38}, number = {2}, year = {2015}, month = {APR}, pages = {435-442}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

Here we report a remarkable transformation of nitrogen-doped multiwalled carbon nanotubes (MWCNTs) to size selective nitrogen-doped graphene quantum dots (N-GQDs) by a two-step electrochemical method. The sizes of the N-GQDs strongly depend on the applied anodic potential, moreover increasing potential resulted in a smaller size of N-GQDs. These N-GQDs display many unusual size-dependant optoelectronic (blue emission) and electrocatalytic (oxygen reduction) properties. The presence of N dopants in the carbon framework not only causes faster unzipping of MWCNTs but also provides more low activation energy site for enhancing the electrocatalytic activity for technologically daunting reactions like oxygen reduction. The smaller size of N-GQDs has shown better performance as compared to the large N-GQDs. Interestingly, N-GQDs-3 (size = 2.5 +/- 0.3 nm, onset potential = 0.75 V) show a 30-mV higher positive onset potential shift compared to that of N-GQDs-2 (size = 4.7 +/- 0.3 nm, onset potential = 0.72 V) and 70 mV than that of N-GQDs-1 (size = 7.2 +/- 0.3, onset potential = 0.68 V) for oxygen reduction reaction (ORR) in a liquid phase. These result in the size-dependent electrocatalytic activity of N-GQDs for ORR as illustrated by the smaller sized N-GQDs (2.5 +/- 0.3 nm) undoubtedly promising metal-free electrocatalysts for fuel cell applications.

}, keywords = {fuel cells, MWCNTs, N-GQDs, oxygen reduction reaction, unzipping}, issn = {0250-4707}, doi = {10.1007/s12034-014-0834-3}, author = {Shinde, Dhanraj B. and Dhavale, Vishal M. and Kurungot, Sreekumar and Pillai, Vijayamohanan K.} }