The synergistic effect of POM-π interaction and solid phase amidation on the visible light photocatalytic of g–C3N4–based photocatalyst

Abstract

Due to the unique ability of Keggin-type polyoxometalate (POM) to remain stable when accepting electrons to form mixed valence POM, organic-POM hybrid materials can complete multi-electron transfer while maintaining structural stability. The organic-POM hybrids photocatalysts prepared using organic materials and POM as raw materials have been developed to form new energy bands and crystal structures. This not only enhances their quantum efficiency and but also expands their visible light response range. Nevertheless, organic-POM hybrids, featuring organic amines as ligands, are prone to photoetching, impeding g-C3N4's progress in this area. In this paper, the amino group of g-C3N4 was converted into imide ring by solid phase amidation method, which overcame this obstacle and converted g-C3N4 into g-C3N4 based polyimide (CNPI) with enhanced photoelectric properties. XRD, IR spectrum, and XPS data indicate that CNPI is more tightly integrated with potassium phosphotungstate (KPW) than g-C3N4, demonstrating superior electron transport capabilities and potentiated POM-π interactions. In terms of photocatalytic efficacy, CNPI/KPW-30 % exhibits an impressive degradation rate constant of 0.5458 h−1 for imidacloprid, attributed to its compact microstructure and superior charge transfer capability. While maintaining good photocatalytic stability, the mineralization rate of CNPI/KPW-30 % to imidacloprid was 55.25 %. In addition, h+ and ·O2− were identified as active species through trapping agent experiments, and the degradation pathway was advanced by ESR technology analysis.