In-situ fabrication of BiOCl/OVs–BiPO4 heterojunctions with enhanced photocatalytic destruction performance

In this work, BiOCl/OVs–BiPO₄ heterojunction photocatalysts were successfully in-situ prepared by treating of BiPO₄ with dilute hydrochloric acid (HCl) under hydrothermal condition. Systematically characterization results confirm that BiOCl/BiPO₄ heterojunctions have been successfully in-situ constructed and oxygen vacancies (OVs) are significantly increased. The OVs on the surface of the BiOCl/OV_S–BiPO₄ heterojunctions photocatalyst and the interface electric field at the interface of the heterojunctions effectively accelerate the separation and migration of photogenerated carriers, and the surface OVs provide more sites for adsorption and reaction. Consequently, BiOCl/OVs–BiPO₄ heterojunction photocatalysts have higher separation rate of photoexcited e⁻/h⁺ pairs and exhibit ascendant photocatalytic degradation activity. Electron paramagnetic resonance (EPR) technology and free radical capture experiments give strong evidence that ·O₂⁻ exists in the reaction system and is the leading species during the degradation process. The experimental results reveal that the degradation efficiency of rhodamine B (RhB) over BiPO₄ treated with 3 ml of 0.1% dilute hydrochloric acid (3HCl-BPO) is 2.42 times of that over the reference BiPO₄. After ultraviolet (UV) light illumination for 20 min, the destruction degree of RhB on the 3HCl-BPO sample reaches 99%. Moreover, the degradation rate of tetracycline (TC) is also obviously improved over 3HCl-BPO compared with that on the reference BiPO₄ after 40 min exposure to ultraviolet light. The excellent stability of the sample was demonstrated by five cycles. A reasonable enhancement mechanism for BiOCl/OVs–BiPO₄ heterojunctions was proposed to elucidate the boosted photocatalytic performance. This work offers a facile and reliable reference to design high performance BiPO₄-based photocatalysts for environment purification.

Graphical abstract