Supporting Information

Transcription

1 1 Supporting Information Photoluminescent Carbogenic Dots A. B. Bourlinos, A. Stassinopoulos, D. Anglos, R. Zboril, V. Georgakilas, E. P. Giannelis *, Institute of Materials Science, NCSR Demokritos, Ag. Paraskevi Attikis, Athens 15310, Greece Institute of Electronic Structure and Laser, Foundation for Research and Technology- Hellas, P.O. Box 1385, GR Heraklion, Crete, Greece Department of Physical Chemistry, Palacky University, Olomouc 77146, Czech Republic Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA Experimental details Synthesis of C-SALT. 2 g H 2 N(CH 2 ) 10 COOH (Aldrich) were added in 25 ml H 2 O and neutralized by 0.45 g NaOH. The solution was filtered and added to 25 ml of an aqueous solution containing 2 g citric acid (Carlo Erba). After vigorous stirring for a few minutes the thick precipitate was collected by filtration and partially dried at room temperature for one day. The resulting wet paste was further dried at 85 o C for 2 h. This drying process is essential in terms of final yield and dispersion properties. The solid was crashed into a fine powder and directly oxidized in air at 300 o C for 2 h at a heating rate of 10 o C min -1 using a muffle oven. The crude product was extracted with 25 ml of hot water using sonication sporadically. The mixture was centrifuged in order to remove any insoluble particles and the supernatant aqueous layer was collected. The ph of the latter was adjusted to 2 with conc. HCl (37 %) yielding a bulk precipitate that was rinsed with water and suspended in 25 ml water. The solid suspension was treated back with 0.2 g NaOH and centrifuged in order to remove excess of NaOH. The remaining precipitate was re-dispersed in 20 ml water and centrifuged in order to remove minor insoluble particles. The resulting clear, deep brown colloidal dispersion consists of ionic carbogenic nanoparticles in water (C-SALT, yield: 10 %). The dispersion is stable for a long period of time with no signs of precipitation. Alumina TLC in water (single band,

2 2 R f ~0) suggested the presence of very pure materials void of any impurities. Elemental analysis gave the average formula: (C 3.3 O 3 H 4 )HN(CH 2 ) 10 COONa. Synthesis of C-ZEO. 1 g NaY zeolite (Aldrich) was suspended in 50 ml water. A solution of 1 g 2,4-diaminophenol dihydrochloride (Fluka) in 5 ml water was added to the zeolite suspension and the mixture was stirred for 30 min before centrifugation and washing of the solid. The same exchange procedure was repeated once more. The resulting solid was re-suspended in 50 ml water followed by the addition of a solution of 3 g 2,4-diaminophenol dihydrochloride in 10 ml water. After overnight stirring the material was centrifuged, washed thoroughly with water and acetone and air-dried. The TGA profile of this derivative under air revealed that the organic fraction decomposes near 240 o C. Thus, the sample was oxidized in air at 300 o C for 2 h at a heating rate of 10 o C min -1 in a muffle oven to produce the zeolite-supported carbogenic nanoparticles (C-ZEO). Note that the reaction temperature is well above the decomposition temperature of the organics present in the zeolite. The carbogenic content of C-ZEO was 10 % w/w with an average composition C 3.3 H 1.7 NO 1.1. Instrumentation. XRD patterns were recorded on a Siemens XD-500 diffractometer using CuKF radiation. IR spectra were taken on an FT-IR spectrometer (Bruker Equinox 55/S) using KBr pellets. TEM was carried out on a JEOL JEM 2010 microscope operated at 200 kv (LaB6 cathode, point resolution 1.94 Å) using a holey-carbon coated copper grid. HR-TEM was performed on a JEOL JEM 3010 microscope operated at 300 kv (LaB6 cathode, point resolution 1.7 Å) equipped with an EDX detector. Images were recorded by a CCD camera at a resolution of pixels. TGA traces were obtained with a Perkin-Elmer Pyris TGA/DTA instrument at a heating rate of 10 o C min -1. The absorption optical spectra were collected on a Cary 50 UV/Vis spectrophotometer (Varian), while fluorescence emission spectra were recorded on a Fluoromax-P fluorimeter (Jobin-Yvon). Elemental analysis (C, H, N) was performed using a Perkin Elmer 2400 analyzer.

3 3 Supporting Information Figures Figure S1. XRD pattern (left) and FT-IR spectrum (right) of C-SALT.

4 4 Figure S2. XRD patterns (left) and FT-IR spectra (right) of NaY zeolite (a) and C-ZEO (b), respectively.

5 5 Figure S3. XRD pattern (left) and FT-IR spectrum (right) of the carbogenic nanoparticles derived after etching C-ZEO with HF.