Fabrication of hierarchical BiOCl-CoP heterojunction on magnetic mesoporous silica microspheres with double-cavity structure for effective photocatalysis

In this research, the magnetic mesoporous silica microspheres with double-cavity structure (DHFS) were first synthesized by combining the hydrothermal technique, sol-gel hydrolysis and chemical etching method, then the BiOCl-CoP-x (BC-x, x = 1, 2, 3) heterojunctions were fabricated on the surface of the amino-functionalized DHFS microspheres. The morphologies, crystal characteristics, compositions and photoelectrochemical properties of the samples in different stages were characterized by various technologies. Furthermore, methylene blue (MB), as the targeted organic pollutant, was used to study the enriching property and activity of the photocatalysts by the corresponding adsorption and degradation experiments. Research showed that the introduction of the DHFS microspheres could significantly enhance the adsorption ability of the photocatalyst for the existence of concentration gradient effect of the mesoporous and double-cavity structure, so that the DHFSBC-2 possessed the most superior activity under visible-light illumination (VLI) for the effective fabrication of heterojunction interfaces between BiOCl and CoP NPs. More importantly, this photocatalyst exhibited very strong photo-stability, and no decrease of the photocatalytic activity could be observed after being recycled for several times.