Novel in-situ Ag-decorated trithiocyanuric acid polymer with superior visible light photocatalytic activity

Abstract

A novel Ag-decorated trithiocyanuric acid polymer (Ag-TTCA) was fabricated via a photocatalytic reduction method based on the strong affinity between Ag ion and trithiocyanic acid (TTCA). The as-prepared photocatalysts were characterized, and the paralleled experiments were conducted on the photocatalytic oxidation of bisphenol A (BPA) to evaluate the photocatalytic activity. Compared with TTCA, Ag-TTCA has a much higher photocatalytic activity. The 0.08Ag-TTCA catalyst can remove BPA (20 mg L−1) in 240 min with a degradation efficiency as high as 96.4 %. The improved photocatalytic performance of Ag-TTCA can be attributed to the dispersed nanoparticle morphology and unique electronic structure. The dispersed nanoparticle morphology of Ag-TTCA can provide more active sites for the adsorption and degradation of pollutants. After silver modification, the light absorption threshold of TTCA is redshifted from 466 nm to 522 nm, and the corresponding band gap is reduced from 2.74 eV to 2.54 eV, which broadens the light absorption range of the photocatalyst and significantly enhances the light absorption capacity. Moreover, metal silver can trap photogenerated electrons and generate surface plasmon resonance (SPR) when illuminated by sunlight, which can effectively promote the separation of electron-hole pairs. Trapping experiment indicates that photogenerated holes, singlet oxygen and superoxide free radicals are the main active species in photocatalytic system.