Preparation of Mo6+, Gd3+-doped TiO2 nanotube arrays and study of their organization and photocatalytic properties

Abstract

Titanium dioxide nanotube arrays doped with [Formula: see text], [Formula: see text], and [Formula: see text]-[Formula: see text] were prepared by anodic oxidation combined with a two-step electrochemical method. The crystalline structure, surface morphology, light absorption properties, and crystalline transformation process were characterized using XRD, SEM, UV–Vis, DSC, and FT-IR. The results show that [Formula: see text] and [Formula: see text] single doping of TiO2 can promote the transformation of amorphous TiO2 to anatase and inhibit the transformation of anatase phase to rutile, but [Formula: see text]–[Formula: see text] co-doping promotes both phase transformations, and the anatase compositions of the TiO2 heat-treated at 450∘C were all over 91%; The tube diameters of TiO2 nanotubes were all around 60–70 nm; the [Formula: see text] - and [Formula: see text] -doped TiO2 light absorption peaks were all significantly red-shifted, with the most obvious change in the [Formula: see text]–[Formula: see text] co-doping, where the forbidden bandwidth was reduced to 3.01 eV; The degradation rate of pure TiO2 photocatalytic degradation of methylene blue for 8 h was only 41.9%, while the degradation rate of [Formula: see text]–[Formula: see text]co-doped TiO2 was as high as 91.51%; [Formula: see text], [Formula: see text], single doping and co-doping could increase the amount of •OH, •OOH adsorbed on the surface of TiO2, which led to the improvement of catalytic performance.