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

Abstract

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 (λ > 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 ˙O₂⁻ were responsible for the degradation of MO/TC. Finally, the corresponding photocatalytic mechanism was proposed.