Decomposition-Reassembly Synthesis of a Silverton-Type Polyoxometalate 3D Framework: Semiconducting Properties and Photocatalytic Applications.

ABSTRACT

Polyoxometalate-based all-inorganic three-dimensional (3D) frameworks have recently attracted attention as a unique class of materials due to their unique physicochemical properties and a wide field of application with excellent prospects. We herein synthesized a novel all-inorganic 3D framework material based on cobalt-substituted Silverton-type polyoxometalate, H6{Co6W10O42[Co(H2O)4]3}·2H2O (Co9W10), which was successfully constructed using Na12[WCo3II(H2O)2(CoIIW9O34)2]·46-48H2O (Co5W19) and Co(NO3)2·6H2O as starting materials in a hydrothermal reaction via a decomposition-reassembly route together with the rational adjustment of pH values. Co9W10 has been structurally characterized using single-crystal X-ray diffraction. Photocurrent response, band-gap (Eg) value, and the VB-XPS spectrum have been measured to reveal the semiconducting property of Co9W10. Furthermore, we synthesized x% PTh/Co9W10 composites (PTh = polythiophene, x = 0.5, 1, 2, 5) for photodegradation of tetracycline hydrochloride (TH) to evaluate the photocatalytic activities of title composites. Due to the optimal molar ratio of hybrids and matching energy levels, 2% PTh/Co9W10 composites show the best photocatalytic activities among these composites.