Amplifying chlorinated phenol decomposition via Dual-Pathway O₂ Activation: The impact of zirconium loading on BiOCl

The effectiveness of photocatalytic molecular oxygen (O₂) activation in pollutant removal relies on the targeted production of reactive oxygen species (ROS). Herein, we demonstrate the dual-pathway activation of O₂ on BiOCl through zirconium (Zr) loading. The incorporation of Zr onto the surface of BiOCl not only leads to an increased generation of oxygen vacancies (OV) but also fosters a coupling between the d electrons of Zr and OV, forming dual-active sites known as Zr-oxygen vacancies (Zr-OV). Generally, OV adsorbs O₂ and transfers one electron directly to form superoxide radicals (•O₂^-). Contrary to the conventional single-electron direct activation of O₂ to form •O₂^-, Zr-OV exhibits more flexible coordination and superior electron-donating capabilities. It facilitates O₂ conversion to peroxide radicals (O₂^2-) and enables the subsequent generation of •O₂^- from O₂^2-, significantly promotes the dechlorination and mineralization efficiency of chlorophenol under visible light. This study presents a straightforward strategy to precisely regulate ROS production by expanding pathways, shedding light on the critical role of managing ROS generation for effective pollutant purification.