Photoelectrocatalytic Degradation of Paraquat by Pt Loaded TiO₂ Nanotubes on Ti Anodes

Materials (Basel). 2018 Sep 13;11(9):1715. doi: 10.3390/ma11091715.

Abstract

Nanotube structured TiO₂ on Ti surface were prepared in ethylene glycol (Ti/TiO₂NTEG) medium by anodic oxidation method with different times and then the plates were calcinated at different temperatures. Non-nanotube structured Ti/TiO₂, prepared by thermal oxidation method, and nanotube structured TiO₂ on Ti plate in hydrogen fluoride solution were also prepared for comparison. Pt loaded Ti/TiO₂NTEG photoanodes were also prepared by cyclic voltammetry method with different cycles and the optimum loaded Pt amount was determined. Photoanodes were characterized by using X-ray Diffraction (XRD), Scanning Electron Microscopy-Energy-Dispersive X-ray Analysis (SEM-EDX), and photocurrent methods. XRD analyses proved that almost all TiO₂ is in anatase phase. SEM analyses show that nanotubes and Pt nanoparticles on nanotube surface are dispersed quite homogeneously. The longest nanotubes were obtained in the ethylene glycol medium and the nanotube length increased by increasing applied anodic oxidation time. In addition, a linear correlation between nanotube length and XRD peak intensity was found. Moreover, SEM-EDX and XRD analyses evidence that Pt nanoparticles on nanotube surface are metallic and in cubic structure. Photoelectrocatalytic degradation of paraquat was performed using the prepared photoanodes. Moreover, electrocatalytic and photocatalytic degradations of paraquat were also investigated for comparison, however lower activities were observed. These results evidence that the photoanodes show a significant synergy for photoelectrocatalytic activity.

Keywords: Pt loaded TiO2; TiO2 nanotube; degradation; paraquat; photoelectrocatalysis; polar herbicide.