Graphene as a 2D Support Shuttle for Separating Photogenerated Charges: an Example combining Copper and TiO2 Nanotubes

Abstract

SSCI-VIDE+CARE+FDA:CGU:GBEInternational audienceTiO2 nanotubes (NTs), even if better photocatalysts than classical 3D particles, still suffer from recombination of electron-hole pairs. In a previous study, we found that adding graphene oxide (GO) to NTs help to improve the separation of photogenerated charges. However, the driving force for the transfer of electrons from TiO2 to GO was also found to come from the reduction of functional oxygen groups on graphene layers leading to instability under irradiation. Herein, an alternative is proposed through the addition of Cu NPs onto GO without contact with TiO2 NTs leading to a physical separation of charges with GO acting here only as a 2D support shuttle without inactivation. Comparison was performed between Cu/TiO2 NTs and Cu/(R)GO/NTs systems. On Cu/TiO2 NTs, results show a stabilization of Cu NPs at a +I oxidation state due to a strong interaction with TiO2 NTs leading to photocatalytic activity under visible light for the formic acid (FA) photodegradation. On Cu/(R)GO/TiO2 systems, strong activity was observed using non-reduced GO due to a physical separation of Cu NPs and TiO2 nanotubes confirming our assumption while reducing GO leads to a relocation of Cu NPs onto TiO2 NTs and loss of any beneficial effect due to GO. Application for H2 production will also be presented