Study of the influence of anodizing parameters on the photocatalytic activity of preferred oriented TiO2 nanotubes self-doped by carbon

Abstract

Nanotubular TiO2 arrays are obtained by anodizing in a fluorine-ion-containing organic-based electrolyte. Synthesis of the amorphous nanotubular arrays is carried out at different anodizing voltages fixed in the range from 20 to 60 V. The following annealing at 400 °C in hydrogen and air flows enables a highly crystallized anatase crystal structure with a preferred orientation by (101) and (004) planes to be obtained. The film on substrate samples was characterized by SEM, XRD, XPS, and UV–vis absorption methods. The photoelectrochemical properties of chemical pure nanotubular titania are comprehensively studied using the incident photon-to-electron conversion efficiency technique. The bandgap of the obtained material is observed to be tuned from 3.4 to 3.2 eV with changes in anodizing voltage. The effect of self-doping by carbon on the photocatalytic properties for nanotubular titanium oxide with a preferred orientation is presented. The integral photoconversion efficiency in the UV and visible range is increased significantly from 1.07 to 8.30%. The presented study presents peculiarities of the preferred oriented nanotubular TiO2 for photocatalytic decomposition processes and reveals the additional approaches as effective routes to increase the efficiency of this material before further doping and decoration.