Flower-like ZnO/BiOI p–n heterojunction composites for enhanced photodegradation of formaldehyde and dyes

The fabrication of p–n heterojunctions was considered as a promising strategy to improve the photocatalytic efficiency of the catalyst, because such junction can effectively promote separation of carriers and improve the catalytic performance. Herein, nanoflower like p–n heterojunction photocatalyst ZnO/BiOI (abbreviated as ZB-x) was prepared by simple solution coprecipitation. Under visible light, ZnO/BiOI p–n heterojunction photocatalyst showed enhanced degradation rate toward Rhodamine B (RhB) and formaldehyde (HCHO) photodegradation. The degradation rates of RhB and HCHO by optimized complex ZB-0.5 in 60 min were 95% and 60%, respectively. The p-type BiOI with narrow band gap can effectively enhance the visible light absorption, and its p–n heterojunction with ZnO can significantly improve the separation efficiency and transfer rate of photogenerated electron hole pairs. Meanwhile, multi-dimensional nanoflower structure is not only conducive to light reflection and improve light utilization, but also can expose more catalytic active sites. This p–n heterojunction nanocomposite has a good effect on improving environmental pollution problems.