▎ 摘　　要

In this report, we studied the optical properties of hybrid spherical structures consisting of alternating nanosheets of titania (TiO2) and graphene oxide (GO) prepared by a layer-by-layer self-assembly technique. Compared to samples with only TiO2 spheres or GO nanosheets, a blue-to-red light emission band emerges and persists in this novel composite material even after it was further reduced through microwave irradiation. From detailed time-resolved measurements and energy-level structure modeling, this unexpected fluorescent feature was attributed to the indirect optical transitions between TiO2 and the localized sp(2) domains of GO in a charge-separated configuration. (C) 2012 Optical Society of America