Self-assembled hierarchical Bi12TiO20-graphene nanoarchitectures with excellent simulated sunlight photocatalytic activity.

A series of hierarchical Bi12TiO20-graphene nanoarchitectures (Bi12TiO20-GR) with GR loadings from 1% to 10% are fabricated by a single-step solvothermal treatment technique, and the intimate interfacial contact between flexible GR sheets and flower-like Bi12TiO20 nanocrystals is observed in the Bi12TiO20-GR composites. As a novel composite photocatalyst, Bi12TiO20-GR with GR loading of 2% possesses the highest simulated sunlight photocatalytic activity towards the degradation of two typical organic pollutants, methyl orange (MO) and p-nitrophenol (PNP). Furthermore, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Bi12TiO20-GR system is studied, meanwhile, the active species (hVB(+), O2˙(-) and ˙OH) generated in the Bi12TiO20-GR-photocatalyzed PNP degradation system are identified by free radical and hole scavenging experiments. Based on the experimental and theoretical results, the mechanism and pathway of photocatalytic degradation of PNP in the simulated sunlight-irradiating Bi12TiO20-GR system are proposed.