Effects of pH on the hierarchical structures and photocatalytic performance of Cu-doped BiVO4 prepared via the hydrothermal method

Cu-doped BiVO4 with hierarchical structures was prepared by the hydrothermal method at different pH. The corresponding relationship was obtained among pH values of the precursor to phase, morphology, and photocatalytic ability of as-prepared Cu–BiVO4. The results show that, the pH value of the precursor was 5, 6, the as-prepared Cu–BiVO4 were tetragonal phase crystals with sheet-like, polyhedron-like morphologies. The phase transformation from tetragonal phase to monoclinic phase occurred between pH=6 to pH=7. Spherical morphology Cu–BiVO4 with particle sizes in the range of 5 μm could be prepared under the neutral condition (pH=7), which expressed excellent photocatalytic activities for the photodegradation of phenol under visible light irradiation. Whereas leaf-like and rod-like Cu–BiVO4 with monoclinic phase could be obtained within pH=8 and pH=9 respectively. The photocatalytic activities of the as-prepared Cu–BiVO4 samples were evaluated for the photodegradation of phenol under visible light irradiation. The mechanism analysis shown that superoxide radical anion O2−
• was main active radicals in photocatalytic oxidation of phenol as-prepared Cu–BiVO4 samples. The reaction kinetics of the photodegradation of phenol over the Cu–BiVO4 was also established by the way of the Langmuir–Hinshewood model.