Investigation of hydrogen induced fluorescence in C₆₀and its potential use in luminescence down shifting applications

Abstract

Herein the photophysical properties of hydrogenated fullerenes (fulleranes) synthesized by direct hydrogenation utilizing hydrogen pressure (100 bar) and elevated temperatures (350 °C) are compared to the fulleranes CH and CH synthesized by amine reduction and the Birch reduction, respectively. Through spectroscopic measurements and density functional theory (DFT) calculations of the HOMO-LUMO gaps of CH (0 ≤ x ≤ 60), we show that hydrogenation significantly affects the electronic structure of C by decreasing conjugation and increasing sp hybridization. This results in a blue shift of the emission maximum as the number of hydrogen atoms attached to C increases. Correlations in the emission spectra of CH produced by direct hydrogenation and by chemical methods also support the hypothesis of the formation of CH and CH during direct hydrogenation with emission maxima of 435 and 550 nm respectively. We also demonstrate that photophysical tunability, stability, and solubility of CH in a variety of organic solvents make them easily adaptable for application as luminescent down-shifters in heads-up displays, light-emitting diodes, and luminescent solar concentrators. The utilizization of carbon based materials in these applications can potentially offer advantages over commonly utilized transition metal based quantum dot chromophores. We therefore propose that the controlled modification of C provides an excellent platform for evaluating how individual chemical and structural changes affect the photophysical properties of a well-defined carbon nanostructure.

Derived properties from the dipole and generalized oscillator strength distributions of an endohedral confined hydrogen atom

“…Furthermore, the production of a H@C 60 system is an active field of research as a fullerene cavity could be used for hydrogen storage [5] and would present interesting electronic properties, e.g. luminescence [6]. In this regard, a new theoretical method has been recently proposed by Long et al [7] to use the breathing mode of a C 60 cavity under a laser pulse to allow the insertion of a H atom into the fullerene.…”

Optimal hydrogen storage in sodium substituted lithium fullerides

“…Finally, the high occupancy of the t 1g -LUMO states of C 60 by the electrons donated by metals promotes hydrogen chemisorption through the formation of C-H sp 3 covalent bonds. [12][13][14] Since the first study reported by Yoshida et al, 15 lithium and sodium intercalated fullerides have been thoroughly investigated and it was demonstrated that they can reversibly absorb up to 5 and 3.5 wt% H 2 respectively [12][13][14][16][17][18][19][20][21][22][23][24] in their pristine form and up to 6 and 3.7 wt% H 2 when doped with catalysts. 25,26 In particular, Na 6 C 60 can absorb 4 wt% H 2 , 27 with reversible absorption/desorption processes between the Na 6 C 60 H 18 and Na 6 C 60 H 36 species at 375 1C (2.1 wt% H 2 stored), and it can be completely dehydrogenated only at 550 1C.…”

Hydrogenated C60 as High-Capacity Stable Anode Materials for Li Ion Batteries

“…The method for hydrogenating the C 60 has been previously described. 28 Briefly, the C 60 was ground with a mortar and pestle for 5 min to expose more surface area for hydrogenation inside of an argon-filled glovebox. After grinding, the C 60 turns from a shiny black color to a dull brown color.…”