Edge carboxylation-induced charge separation dynamics of graphene quantum dot/cellulose nanocomposites

Graphene quantum dot (GQD)@cellulose nanocomposites possess optoelectronic properties of interest for photovoltaic applications. However, the optoelectronic properties related to the shapes and edge types of GQDs have not been fully explored. In the present work, we investigate the effects of carboxylation on the energy alignment and charge separation dynamics at the interface of GQD@cellulose nanocomposites using density functional theory calculations. Our results show that the GQD@cellulose nanocomposites composed of hexagonal GQDs with armchair edges exhibit better photoelectric performance than those composed of other types of GQDs. Carboxylation stabilizes the energy level of the highest occupied molecular orbital (HOMO) of the triangular GQDs with armchair edges but destabilizes the HOMO energy level of cellulose, resulting in hole transfer from the GQDs to cellulose upon photoexcitation. However, the calculated hole transfer rate is lower than the non -radiative recombination rate because excitonic effects dominate the dynamics of charge separation in GQD@cellulose nanocomposites.

Automated summary

In this study, the effects of carboxylation on the optoelectronic properties of GQD@cellulose nanocomposites were investigated. The results show that hexagonal GQDs with armchair edges exhibit improved photoelectric performance, and carboxylation stabilizes the energy levels of triangular GQDs with armchair edges, facilitating hole transfer to cellulose upon photoexcitation.