Preparation and Catalytic Properties of Graphene-Bismuth Ferrite Nanocrystal Nanocomposite

BiFeO3 (BFO) is a novel recyclable photocatalyst which benefits from its appropriate theoretical band gap and room temperature ferromagnetism, yet the relatively high recombination rate of photogenerated electron-hole pairs and low quantum yield limit its practical catalytic performance. Here, a composite material of reduced graphene oxide and BiFeO3 nanocrystals (RGO-BFO) was successfully prepared via a hydrothermal self-assembly process with about 10wt% RGO loaded 85wt% BFO nanocrystalline (similar to 10 nm). Specific surface area of the composite is about 5 times of that of pure BFO particles. Furthermore, this nanocomposite demonstrates the enhanced ultraviolet absorption behavior as well as its intrinsic visible light absorption, with an energy gap (E-g) of 2.0 eV, which is about 10% lower than BFO particles (2.3 eV). As a result, a significantly higher catalytic efficiency of nearly 100% of the RGO-BFO was obtained as compared to the 25% value of BFO after a 40-min process of adsorption and photodegradation for methylene blue. The improved performances may be attributed to the additional photogenerated electron-hole pairs and lower recombination ratio, which can be proved by the result of photoelectric response. As an intrinsically ferromagnetic material, it could be easily recycled from the solvent system, and its repetitive catalytic efficiency maintained 89.1% after 6 cycles, showing a good catalytic stability.