02077nas a2200169 4500008004100000022001400041245018000055210006900235260007100304300001400375490000800389520130500397100002301702700002401725700003001749856012801779 2009 eng d a1932-744700aPreparation and characterization of rhodium nanostructures through the evolution of microgalvanic cells and their enhanced electrocatalytic activity for formaldehyde oxidation0 aPreparation and characterization of rhodium nanostructures throu a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN a9616-96220 v1133 a

Shape-controlled morphological evolution of nanostructured Rh has been demonstrated with the help of a galvanic displacement reaction using Al in 1 mM aqueous Rh(III) chloride at an open circuit potential 0.99 V and at a temperature of 273 K (room temperature). Nanospheres composed of small nanoparticles of size around 2.9 +/- 0.4 nm having uniform distribution with a FCC pattern have been evolved during the course of the reaction. Electrochemical results coupled with structural and morphological characterization data from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV) suggested the formation of Rh nanostructures. Considering the role of the potential of substrate Al and Rh and diffusion of reactant and product species toward and from the surface of the Al, we proposed the tentative mechanism for the formation of microgalvanic cell. Significantly, these: rhodium nanostructures exhibit enhanced electrocatalytic activity toward many fuel cell reactions as demonstrated by formaldehyde oxidation in 0.5 M NaOH. The present strategy is expected to be valid for preparing many other similar electrocatalysts (Pt, Au, and Pd) capable of exhibiting such a remarkable size- and shape-dependent reactivity.

1 aSathe, Bhaskar, R.1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/preparation-and-characterization-rhodium-nanostructures-through-evolution-microgalvanic-001529nas a2200193 4500008004100000022001400041245012100055210006900176260007100245300001400316490000800330520075400338100002401092700002401116700001901140700002001159700003001179856012601209 2011 eng d a0002-786300aElectrochemical unzipping of multi-walled carbon nanotubes for facile synthesis of high-quality graphene nanoribbons0 aElectrochemical unzipping of multiwalled carbon nanotubes for fa a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a4168-41710 v1333 a

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 ``unzipping'' 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.

1 aShinde, Dhanraj, B.1 aDebgupta, Joyashish1 aKushwaha, Ajay1 aAslam, Mohammed1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/electrochemical-unzipping-multi-walled-carbon-nanotubes-facile-synthesis-high-quality-001961nas a2200217 4500008004100000022001400041245010300055210006900158260007500227300001600302490000700318520113200325653003001457653001301487653001901500653002201519653001701541100002401558700003001582856013101612 2012 eng d a0947-653900aElectrochemical preparation of luminescent graphene quantum dots from multiwalled carbon nanotubes0 aElectrochemical preparation of luminescent graphene quantum dots aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcSEP a12522-125280 v183 a

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.

10aelectrochemical synthesis10agraphene10aNanostructures10aphotoluminescence10aquantum dots1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/electrochemical-preparation-luminescent-graphene-quantum-dots-multiwalled-carbon-nanotubes-001108nas a2200169 4500008004100000022001400041245011100055210006900166260011000235300001400345490000700359520036900366100002400735700002400759700003000783856012500813 2012 eng d a1359-734500aIn situ electrochemical organization of CdSe nanoclusters on graphene during unzipping of carbon nanotubes0 aIn situ electrochemical organization of CdSe nanoclusters on gra aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a3088-30900 v483 a

In situ decoration of very small CdSe quantum dots on graphene nanoribbons (GNRs) has been achieved during the electrochemical unzipping of single walled carbon nanotubes. Critical parameters like the width of the GNRs, size distribution of quantum dots and their organization on GNRs have been shown to be strongly dependent on the electric field and time.

1 aDebgupta, Joyashish1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/situ-electrochemical-organization-cdse-nanoclusters-graphene-during-unzipping-carbon-001179nas a2200205 4500008004100000022001400041245011900055210006900174260011000243300001400353490000600367520032800373100002400701700002400725700002400749700002400773700002500797700002100822856013000843 2012 eng d a2046-206900aMorphology controlled synthesis of LiV(2)0(5)/Ag nanocomposite nanotubes with enhanced electrochemical performance0 aMorphology controlled synthesis of LiV205Ag nanocomposite nanotu aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR a3231-32330 v23 a

Uniformly embedded silver (Ag) nanoparticles in orthorhombic nanotubes (NTs) of lithium vanadium oxide (LVO) synthesized via a facile template-free hydrothermal treatment at low temperature exhibited an excellent morphology with good crystallinity and may act as an exceptional contender for electronic applications.

1 aDiggikar, Rahul, S.1 aDhavale, Vishal, M.1 aShinde, Dhanraj, B.1 aKanbargi, Nihal, S.1 aKulkarni, Milind, V.1 aKale, Bharat, B. uhttp://library.ncl.res.in/content/morphology-controlled-synthesis-liv205ag-nanocomposite-nanotubes-enhanced-electrochemical-000789nas a2200205 4500008004100000022001400041245008200055210006900137260007700206300001400283490000700297653002000304653003500324653001300359653001700372653002900389100002400418700003000442856011100472 2013 eng d a1433-785100aElectrochemical resolution of multiple redox events for graphene quantum dots0 aElectrochemical resolution of multiple redox events for graphene aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJAN a2482-24850 v5210acharging energy10adifferential pulse voltammetry10agraphene10aquantum dots10asingle-electron transfer1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/electrochemical-resolution-multiple-redox-events-graphene-quantum-dots-001415nas a2200193 4500008004100000022001400041245006000055210006000115260012500175300001100300490000800311520069900319100001801018700002001036700002401056700003001080700002001110856009101130 2013 eng d a0003-695100aHysteresis and charge trapping in graphene quantum dots0 aHysteresis and charge trapping in graphene quantum dots aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScAPR a1431040 v1023 a

We report current hysteresis in response to applied voltage in graphene quantum dots of average diameter 4.5 +/- 0.55 nm, synthesized electrochemically using multiwalled carbon nanotubes. In response to step voltages, transient current decay, characteristic of deep and shallow level charge traps with time constants 186 ms and 6 s, is observed. Discharging current transients indicate charge storage of the order of 100 mu C. Trap states are believed to arise due to the fast physisorption of external adsorbates, which are found to have a significant effect on charge transport and changes the resistance of the prepared device by an order of 3. (C) 2013 American Institute of Physics.

1 aKalita, Hemen1 aHarikrishnan, V1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K.1 aAslam, Mohammed uhttp://library.ncl.res.in/content/hysteresis-and-charge-trapping-graphene-quantum-dots01496nas a2200181 4500008004100000022001400041245014700055210006900202260011000271300001600381490000600397520069100403100002301094700002401117700003001141700002001171856012301191 2013 eng d a2040-336400aStabilization of graphene quantum dots (GQDs) by encapsulation inside zeolitic imidazolate framework nanocrystals for photoluminescence tuning0 aStabilization of graphene quantum dots GQDs by encapsulation ins aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a10556-105610 v53 a

Luminescent graphene quantum dots (GQDs) are encapsulated and stabilized in Zeolitic Imidazolate Framework (ZIF-8) nanocrystals. The GQDs are well confined due to the adsorption on the growing face of the ZIF-8 nanocrystals and have a profound effect on the shape of the nanocrystals from rhombic dodecahedron to spherical. Stabilizing GQDs inside the ZIF-8 nanocrystals results in tailoring of the photoluminescence emission (ca. 32 nm, bathochromic shift) of the GQD@ZIF-8 nanocrystal composite even after 3 months of aging under normal laboratory conditions. Also the water adsorption (at STP) capacity increased for the GQD@ ZIF-8 composite as compared to the pristine ZIF-8.

1 aBiswal, Bishnu, P.1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K.1 aBanerjee, Rahul uhttp://library.ncl.res.in/content/stabilization-graphene-quantum-dots-gqds-encapsulation-inside-zeolitic-imidazolate-001740nas a2200169 4500008004100000022001400041245014100055210006900196260009000265300002300355490000600378520098900384100002401373700002101397700003001418856012201448 2014 eng d a2045-232200aCounter-ion dependent, longitudinal unzipping of multi-walled carbon nanotubes to highly conductive and transparent graphene nanoribbons0 aCounterion dependent longitudinal unzipping of multiwalled carbo aMACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLANDbNATURE PUBLISHING GROUPcMAR aArticle No. : 43630 v43 a

Here we report for the first time, a simple hydrothermal approach for the bulk production of highly conductive and transparent graphene nanoribbons (GNRs) using several counter ions from K2SO4, KNO3, KOH and H2SO4 in aqueous media, where, selective intercalation followed by exfoliation gives highly conducting GNRs with over 80% yield. In these experiments, sulfate and nitrate ions act as a co-intercalant along with potassium ions resulting into exfoliation of multi-walled carbon nanotubes (MWCNTs) in an effective manner. The striking similarity of experimental results in KOH and H2SO4 that demonstrates partially damaged MWCNTs, implies that no individual K+, SO42- ion plays a key role in unwrapping of MWCNTs, rather this process is largely effective in the presence of both cations and anions working in a cooperative manner. The GNRs can be used for preparing conductive 16 k Omega sq(-1), transparent (82%) and flexible thin films using low cost fabrication method.

1 aShinde, Dhanraj, B.1 aMajumder, Mainak1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/counter-ion-dependent-longitudinal-unzipping-multi-walled-carbon-nanotubes-highly-001363nas a2200193 4500008004100000022001400041245012200055210006900177260007100246300001400317490000600331520059200337100001800929700002100947700002400968700003000992700001701022856013001039 2014 eng d a2161-165300aMitigating the cytotoxicity of graphene quantum dots and enhancing their applications in bioimaging and drug delivery0 aMitigating the cytotoxicity of graphene quantum dots and enhanci a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a1064-10680 v33 a

Despite the promising photophysical properties of fluorescent graphene quantum dots (GQDs), their cellular toxicity needs to be addressed before their full potential could be completely realized in biomedicine. A simple method for mitigating the toxicity of GQDs by embedding them in PEG matrix is reported here. The enhanced biocompatibility of polymer modified, P-GQDs, is attributed to reduced reactive oxygen species generation, as measured by an intracellular ROS assay. We also demonstrate the enhanced loading and efficient intracellular delivery of therapeutics by P-GQDs.

1 aChandra, Anil1 aDeshpande, Sonal1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K.1 aSingh, Neetu uhttp://library.ncl.res.in/content/mitigating-cytotoxicity-graphene-quantum-dots-and-enhancing-their-applications-bioimaging-002710nas a2200289 4500008004100000022001400041245014600055210006900201260007100270300001200341490000600353520162200359653005601981653002102037653001302058653002702071653003502098100001602133700002402149700001402173700001502187700001602202700002402218700003002242700002302272856012502295 2014 eng d a1936-085100aSequential electrochemical unzipping of single-walled carbon nanotubes to graphene ribbons revealed by in situ Raman spectroscopy and imaging0 aSequential electrochemical unzipping of singlewalled carbon nano a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN a234-2420 v83 a

We report an in situ Raman spectroscopic and microscopic investigation of the electrochemical unzipping of single-walled carbon nanotubes (SWNTs). Observations of the radial breathing modes (RBMs) using Raman spectral mapping reveal that metallic SWNTs are opened up rapidly followed by gradual unzipping of semiconducting SWNTs. Consideration of the resonant Raman scattering theory suggests that two metallic SWNTs with chiralities (10,4) and (12, 0) get unzipped first at a lower electrode potential (036 V) followed by the gradual unzipping of another two metallic tubes, (9, 3) and (10, 1), at a relatively higher potential (1.16 V). The semiconducting SWNTs with chiralities (11, 7) and (12, 5), however, get open up gradually at +/- 1.66 V. A rapid decrease followed by a subsequent gradual decrease in the metallicity of the SWNT ensemble as revealed from a remarkable variation of the peak width of the G band complies well with the variations of RBM. Cyclic voltammetry also gives direct evidence for unzipping in terms of improved capacitance after oxidation followed by more important removal of oxygen functionalities during the reduction step, as reflected in subtle changes of the morphology confirming the formation of graphene nanoribbons. The density functional-based tight binding calculations show additional dependence of chirality and diameter of nanotubes on the epoxide binding energies, which is in agreement with the Raman spectroscopic results and suggests a possible mechanism of unzipping determined by combined effects of the structural characteristics of SWNTs and applied field.

10adensity functional-based tight binding calculations10aElectrochemistry10agraphene10aRaman spectral mapping10asingle-walled carbon nanotubes1 aJohn, Robin1 aShinde, Dhanraj, B.1 aLiu, Lili1 aDing, Feng1 aXu, Zhiping1 aVijayan, Cherianath1 aPillai, Vijayamohanan, K.1 aPradeep, Thalappil uhttp://library.ncl.res.in/content/sequential-electrochemical-unzipping-single-walled-carbon-nanotubes-graphene-ribbons-002322nas a2200241 4500008004100000022001400041245014400055210006900199260010200268300001200370490000700382520137800389653001501767653001101782653001101793653003001804653001401834100002401848700002401872700002401896700003001920856013001950 2015 eng d a0250-470700aElectrochemical preparation of nitrogen-doped graphene quantum dots and their size-dependent electrocatalytic activity for oxygen reduction0 aElectrochemical preparation of nitrogendoped graphene quantum do aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACAD SCIENCEScAPR a435-4420 v383 a

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.

10afuel cells10aMWCNTs10aN-GQDs10aoxygen reduction reaction10aunzipping1 aShinde, Dhanraj, B.1 aDhavale, Vishal, M.1 aKurungot, Sreekumar1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/electrochemical-preparation-nitrogen-doped-graphene-quantum-dots-and-their-size-dependent-001615nas a2200205 4500008004100000245005400041210005400095260000800149300002700157490000800184520096300192100002301155700002401178700002401202700002301226700002101249700003001270700002401300856008501324 2015 eng d00aGraphene nanoribbons as prospective field emitter0 aGraphene nanoribbons as prospective field emitter cJAN aArticle Number: 0231110 v1063 a

Field emission characteristics of graphene nanoribbons (GNRs) synthesized by unzipping of multiwall carbon nanotubes using a facile hydrothermal route have been investigated at a base pressure of 1 x 10(-8) mbar. The values of turn-on field, required to draw an emission current densities of 1 and 10 mu A/cm(2), are found to be 2.8 and 5.8 V/mu m, respectively, and a maximum emission current density of 500 mu A/cm(2) has been drawn at an applied field of 9.8 V/mu m. The emission current stability of the GNRs emitter was studied at preset values of 1 and 10 mu A over a period of 3 h, and is found to be excellent. The field emission results demonstrated herein suggest that GNRs based field emitters can open up many opportunities for their potential utilization as large area field emitters in various vacuum micro-nanoelectronic devices such as flexible field emission displays, portable X-ray, and microwave tubes. (C) 2015 AIP Publishing LLC.

1 aKhare, Ruchita, T.1 aShinde, Dhanraj, B.1 aBansode, Sanjeewani1 aMore, Mahendra, A.1 aMajumder, Mainak1 aPillai, Vijayamohanan, K.1 aLate, Dattatray, J. uhttp://library.ncl.res.in/content/graphene-nanoribbons-prospective-field-emitter