Enhanced photocatalytic activities of Bi2WO6/BiOCl composite synthesized by one-step hydrothermal method with the assistance of HCl

In this work, a Bi2WO6/BiOCl composite phase was successfully prepared by a simple hydrothermal method with the aid of hydrochloric acid (HCl) as Cl source. The influence of concentration of HCl in the hydrothermal reaction solution on the microstructure, composite, optical properties and photocatalytic activities of products was investigated in details. The photocatalytic activity of Bi2WO6/BiOCl composite was evaluated by photodegradation of Rhodamine B (RhB), Malachite green (MG) and Methyl orange (MO) under natural/simulated solar light and/or LED lamp irradiation. Results indicated that nearly 100% of RhB molecules can be degraded over Bi2WO6/BiOCl composite photocatalyst after 80 min natural sun light irradiation, while the degradation over Bi2WO6 and BiOCl under the same condition is 91% and 20%, respectively. Also, after 100 min visible light (LED) irradiation, the degradation efficiency of RhB are about 83%, 91% and 0% for Bi2WO6, Bi2WO6/BiOCl and BiOCl samples, respectively. The significant enhancement in the photocatalytic performance of Bi2WO6/BiOCl composite compared with the Bi2WO6 and BiOCl was attributed to the strong interaction between Bi2WO6 and BiOCl, which effectively inhibits the recombination of photogenerated electron-hole pairs at the interface of two semiconductors. Based on radical-scavenger experiments, the holes (h+) and superoxide radicals (
- O2-) are determined as the main active species in the photocatalytic degradation process of RhB over Bi2WO6/BiOCl composite. Furthermore, based on experimental results, the main reactions for photocatalytic degradation of RhB were proposed.