02323nas a2200241   4500008004100000022001400041245014400055210006900199260010200268300001200370490000700382520137800389653001501767653001101782653001101793653003001804653001401834100002401848700002401872700002401896700003001920856013101950       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<p>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.</p>10afuel cells10aMWCNTs10aN-GQDs10aoxygen reduction reaction10aunzipping1 aShinde, Dhanraj, B.1 aDhavale, Vishal, M.1 aKurungot, Sreekumar1 aPillai, Vijayamohanan, K.  uhttps://library.ncl.res.in/content/electrochemical-preparation-nitrogen-doped-graphene-quantum-dots-and-their-size-dependent-0