Highly efficient and reusable BiOCl photocatalyst modulating by hydrogel immobilization and oxygen vacancies engineering

Abstract

• BiOCl nanosheets are immobilized by calcium alginate hydrogel through a simple crosslinking process. • BOC-CA hydrogel beads can float on the water surface. • The hydrogel beads show enhanced photocatalytic effect during the cycled ultraviolet irradiated degradation process. • The porous structure of the beads provides channels for the transport of ultraviolet induced OVs of BiOCl photocatalysts. • The hydrogel beads have excellent recovery rate and high photocatalytic efficiency over 24 degradation cycles. Photo-induced oxygen vacancies (OVs) are widely introduced as active sites in BiOCl to improve photocatalytic performance. Herein, we propose a strategy to take advantage of OVs of BiOCl nanosheets, which are immobilized in the network of water-rich calcium alginate (CA) hydrogel beads. By modulating the porous structure of the hydrogel, the OVs irradiated by UV light on the surface of BiOCl can be rapidly diffused to the deep inner of the beads, and then they disappear after the beads are immersed into the water for hours, which further enables the regeneration of even better BiOCl-CA beads. This reactive cyclic channel in a water-rich environment improves the transport of photogenerated carriers and achieves excellent cyclic photocatalytic performance. This work not only improves the recovery efficiency of photocatalytic materials but also puts forward a new system of BiOCl based hydrogel beads that can be used repeatedly in wastewater treatment.