Is Graphene a Stable Platform for Photocatalysis? Mineralization of Reduced Graphene Oxide With UV-Irradiated TiO₂ Nanoparticles

The recent thrust in utilizing reduced graphene oxide (RGO) as a support for nanostructured catalyst particles has led to the claims of improved efficiency in solar cells, fuel cells, and photocatalytic degradation of pollutants. Specifically, the robust TiO2 system is often coupled with RGO to improve charge separation and facilitate redox reactions. Here, we probe the stability of RGO in the presence of UV-excited TiO2 in aqueous media and establish its reactivity toward OH• radicals, a primary oxidant generated at the TiO2 surface. By probing changes in absorption, morphology, and total organic carbon content (TOC), we conclusively demonstrate the vulnerability of RGO toward OH• attack and raise the concern of its use in many applications where OH• are likely to be formed. On the other hand, the OH• radical-mediated mineralization could also enable new approaches in tackling environmental remediation of nanocarbons such as RGO, carbon nanotubes, and fullerenes.