Phonon energy transfer in graphene–photoacid hybrids

Abstract

Three water-soluble pyrene derivatives, i.e., 1-pyrenesulfonic acid sodium salt (PAS), 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS), and 6,8-dihydroxy-1,3-pyrenedisulfonic acid disodium salt (DHPDS), were employed in noncovalent functionalization of graphene. The phonon coupling interaction between the HPTS and DHPDS photoacids and graphene was demonstrated by UV–vis and photoluminescence spectroscopies, and the proposed mechanism of the phonon transfer was verified by temperature-dependent absorption spectroscopy. Graphene plays the role as a modulator in these graphene/photoacid hybrid systems, which switches the equilibrium between different species of the photoacids. Current work presents the pioneering investigation of phonon coupling (phonon energy transfer) in the graphene–photoacid systems.