Highly Transparent Layer-by-Layer Nanoassembled Multicomponent Films of TiO2 and Graphene for Increased Photocatalytic Performance

Abstract

Here, we report novel highly transparent and photoactive multicomponent films for enhanced photocatalytic applications. Some films are based on intimately interfaced TiO2 nanoparticles and few-layer graphene (FLG) assembled through an environmentally friendly aqueous layer-by-layer (LbL) process. In contrast to reduced graphene oxide-based systems, directly exfoliated FLG was employed in order to preserve the intrinsic electronic conductivity of graphene and promote an efficient interfacial charge separation. The highly transparent and nanoporous LbL architecture minimizes photon scattering and enables precise control of film thickness, TiO2 loading, and photon absorption. The incorporation of FLG strongly improves charge separation, limits charge recombination, and reduces catalyst deactivation through enhanced storage of sulfur-containing byproducts. The photocatalytic activity was evaluated through the photo-oxidation of diethyl sulfide (DES), used as a model compound for mustard gas. TiO2/FLG multilayers exhibit photocatalytic activities up to 35-fold higher than conventional drop-cast TiO2 coatings and up to 6-fold higher than LbL films without FLG at comparable TiO2 loadings. Beyond the material composition itself, these results demonstrate that transparent and nanoporous LbL nanoarchitectures provide a powerful strategy for optimizing photon management and interfacial charge transfer in photocatalytic coatings.