One step fabrication of C-doped BiVO4 with hierarchical structures for a high-performance photocatalyst under visible light irradiation

A novel sol-gel method was developed for the fabrication of a C-doped BiVO4 (BVOB@xC) photocatalyst with fine hierarchical structures templated from Papilio paris butterfly wings. The fine hierarchical butterfly wing structures of BVOB@xC were confirmed by the SEM and TEM observations. The doped carbon in BVOB@xC was formed in situ from the biotemplate during a calcination process and the amount of doping could be controlled from 0.6-2.4 wt% by adjusting the calcination temperature. It was found that the sample calcined at 400 degrees C with a carbon content of 1.5 wt% (BVOB@1.5C) demonstrated the best photocatalytic activity in both photocatalytic degradation and O-2 evolution from water splitting (ca. 800 mu mol L-1). Under visible light irradiation (lambda > 420 nm), the photocatalytic O-2 evolution from BVOB@1.5C (ca. 800 mu mol L-1, after 5 h) is 16 times higher than that of pure BiVO4 powder (BVOP) (ca. 49 mu mol L-1), and the photocatalytic decomposition efficiency of MB for BVOB@1.5C is 6.3 times higher than that of pure BVOP. The improved photocatalytic performance is attributed to the synergetic effect of the unique morphology and composition control. It is believed that the hierarchical butterfly wing structures of BVOB@1.5C contribute significantly to the absorption enhancement under visible light (480 to 700 nm), which was supported by UV-Vis diffuse reflectance measurements. The photocatalytic performance was further enhanced by the C-doping as it improves the efficient separation and transfer of the photogenerated electrons and holes, as evidenced by the electron paramagnetic resonance (EPR) measurements. This strategy provides a simple one-step method to fabricate a high-performance photocatalyst, which enables the simultaneous control of the crystal phase, morphology, and carbon element doping.