Controlled synthesis of a highly dispersed BiPO4 photocatalyst with surface oxygen vacancies.

Highly dispersed BiPO4 with surface oxygen vacancies was synthesized via a solvothermal-calcination method. It can disperse uniformly in water for more than three days and the optimum photocatalytic activity of this highly dispersed BiPO4 was more than twice as high as that of Degussa P25 due to the oxygen vacancies. The high dispersibility is attributed to a layer of organic matter formed on the surface of BiPO4via the solvothermal approach. Most of the organic matter can be removed by calcination at 450 °C, but a small amount remains, thus the calcined BiPO4 retained its high dispersibility. This high dispersibility maintains a good contact between BiPO4 and the pollutants, resulting in the efficient removal of the pollutants by BiPO4. Besides, calcination at 450 °C also induced the formation of oxygen defects in BiPO4, which promotes the separation of photogenerated charge carriers and thus improves the photocatalytic activity of BiPO4.