Self-assembly of a Ag nanoparticle-modified and graphene-wrapped TiO2 nanobelt ternary heterostructure: surface charge tuning toward efficient photocatalysis

Abstract

In recent years, tremendous research efforts have been made towards developing graphene (GR)-based nanocomposites for photocatalytic applications. In this work, surface-coarsened TiO₂ nanobelts (SC-TNBs) closely enwrapped with monodispersed Ag nanoparticles (NPs) and GR nanosheets (i.e. Ag/GR/SC-TNBs) were fabricated using a facile self-assembly strategy followed by photoreduction. It was found that the as-prepared Ag/GR/SC-TNBs ternary heterostructure exhibited significantly improved photocatalytic performances under irradiation with UV light in comparison with blank SC-TNBs and its binary counterparts owing to the formation of double heterojunctions among the components. The intimate integration of Ag NPs and GR with SC-TNBs achieved by the self-assembly buildup exerts a profound effect on the transfer of photogenerated electrons over the SC-TNBs substrate in which Ag NPs serve as an efficient “electron reservoir” and GR as an electron transporter and collector, thus concurrently prolonging the lifetime of the photogenerated electron–hole pairs and resulting in the remarkably enhanced photoactivity over the Ag/GR/SC-TNBs ternary nanocomposite. In addition, the underlying photocatalytic mechanism was elucidated and the primary active species were determined.