N-Doped graphene/C₆₀ covalent hybrid as a new material for energy harvesting applications

N-Doped graphene (N-G) was chemically functionalized by N-alkylation with the well-known electron acceptor C₆₀. The degree of functionalization and the key structural features of the N-G/C₆₀ hybrid were systematically investigated by a number of techniques including thermogravimetric analysis, X-ray photoelectron and Raman spectroscopies and transmission electron and atomic force microscopies. Absorption and electrochemical studies revealed interactions between the N-G and C₆₀ while the fluorescence of C₆₀ within the hybrid was found to be fully quenched. Evidence for the occurrence of excited state charge transfer from the singlet excited C₆₀ to N-G in the hybrid was obtained from femtosecond transient absorption studies covering the visible-near-IR regions. Electron-pooling experiments performed in the presence of a sacrificial electron donor and a second electron acceptor, methyl viologen, revealed the accumulation of the one-electron reduced product of methyl viologen upon continuous irradiation of the N-G/C₆₀ nanohybrid, thus revealing the utility of this material in photocatalytic energy harvesting applications.