Pt/POMs/TiO2 composite nanofibers with an enhanced visible-light photocatalytic performance for environmental remediation

Herein, a novel series of PMo12-TiO2 composites deposited with Pt nanoparticles (NPs), namely X%Pt/PMo12/TiO2 (PMo12 = H3PMo12O40; X stands for wt% of Pt to the PMo12/TiO2 sample and X = 3, 5, 8, and 10), were prepared through a simple electrospinning/calcination method, followed by photoreduction. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that Pt NPs with an average size of 10 +/- 5 nm are well dispersed on the PMo12/TiO2 nanofibers. Photocatalytic tests revealed that the as-prepared Pt/PMo12/TiO2 composite catalysts exhibited excellent and persistent photocatalytic activity for removing methyl orange, tetracycline, Bisphenol A and Cr(vi) under visible-light illumination (lambda > 420 nm). Among the as-prepared composites, the 8%Pt/PMo12/TiO2 sample displayed the best photocatalytic activity with the rate constants of 0.011 min(-1) (MO), 0.043 min(-1) (TC), 0.00615 min(-1) (Bisphenol A) and 0.053 min(-1) (Cr(vi)). The addition of POM PMo12 to the composites enhanced the visible-light adsorption and redox ability of TiO2. Furthermore, Pt NPs exhibited localized surface plasmon resonance (LSPR) absorption, therefore improving the absorption of visible light by PMo12/TiO2. Additionally, intense local electromagnetic fields resulted from LSPR, which greatly facilitated the separation of photo-produced charge carriers in Pt/PMo12/TiO2. The results of free radical- and hole-trapping tests suggested that OH and O-2(-) were responsible for the degradation of MO/TC. Finally, the corresponding photocatalytic mechanism was proposed.