Copper phthalocyanine modified hydrogel inverse opal beads for enhanced photocatalytic removal of dyes

Photocatalysis is considered as a promising technology for dye wastewater remediation. Due to their excellent hydrophilicity, optical transparency and abundant functional groups, various hydrogel-based catalysts have been developed for photocatalytic degradation of pollutants, but their light absorption efficiency and photocatalytic kinetics still need to be further improved. Herein, we use assembled silica microspheres as sacrificial templates and infuse monomers within the pores for UV polymerization to form poly (acrylamide-acrylic acid copolymer) hydrogel inverse opal beads (PACA HIOBs). The slow light effect of the inverse opal structure can increase the contact time between the catalyst and visible light, thereby enhancing the light absorption and utilization efficiency. The ordered porous scaffold provides more active sites for copper phthalocyanine (CuPc) loading to further improve the separation efficiency of photoexcited electron-hole pairs. Under light irradiation, CuPc-PACA HIOBs exhibit superior degradation efficiency and kinetics for anionic dyes in pore-confined water, and center dot O-2(-) acts as the dominant reactive oxygen species in the photocatalytic process. Moreover, CuPc-PACA HIOBs can be used as an indicator to reveal the degradation process of dyes based on the colour change of the photonic crystal. This work presents a strategy for constructing hydrogel-based catalysts with enhanced photodegradation performance and broadens their application in water treatment.