title: In-situ Evidence of the Redox-State Dependence of Photoluminescence in Graphene Quantum Dots.
abstract: Changes in the optical properties of graphene quantum dots (GQD) during electrochemical reduction and oxidation were investigated by photoluminescence (PL) spectroelectrochemistry, which provided direct in situ evidence of the dependence of GQD luminescence on their redox state. We demonstrated that GQD PL intensity was enhanced upon reduction (quantum yield increased from 0.44 to 0.55) and substantially bleached during oxidation (quantum yield ∼0.12). Moreover, PL emission blue/red-shifted upon GQD reduction/oxidation, rendering information about electronic transitions involved in the redox processes, namely, the π → π* and the n → π* transitions between energy levels of the aromatic sp2domains and the functional groups, respectively. PL intensity changes during GQD reduction/oxidation resulted from a variation in structural changes in GQD as a result of charge injection, as corroborated by in situ Raman spectroelectrochemistry.
authors.affiliation: Department of Chemistry, Universidad de Burgos , Pza. Misael Bañuelos s/n, E-09001 Burgos, Spain.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Barrera
authors.affiliation: Department of Chemistry, Universidad de Burgos , Pza. Misael Bañuelos s/n, E-09001 Burgos, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Ibañez
authors.affiliation: Department of Chemistry, Universidad de Burgos , Pza. Misael Bañuelos s/n, E-09001 Burgos, Spain.
authors.forename: Aranzazu
authors.initials: A
authors.lastname: Heras
authors.affiliation: IK4-CIDETEC, Materials Division, P° Miramón 196, E-20009 San Sebastián, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Ruiz
authors.affiliation: Department of Chemistry, Universidad de Burgos , Pza. Misael Bañuelos s/n, E-09001 Burgos, Spain.
authors.forename: Alvaro
authors.identifier: http://orcid.org/0000-0003-0339-356X
authors.initials: A
authors.lastname: Colina