Characterization and Photocatalytic Performance of Potassium-Doped Titanium Oxide Nanostructures Prepared via Wet Corrosion of Titanium Microspheres

Abstract

Potassium doped titanium oxide (KTiOx) nanowires were prepared by the wet corrosion process (WCP) and their photocatalytic effects were systematically characterized. For the synthesis of KTiOx, the potassium hydroxide concentration of the WCP was varied in order to obtain nano-structures with different surface area and surface charge. Structural and crystalline properties of KTiOx were studied by means of X-ray diffraction, scanning and transmission electron microscopy. Chemical composition was determined by X-ray fluorescence and energy-dispersive X-ray analysis. Photocatalytic performance was investigated as a function of the surface area, pH, and crystalline structures by studying the degradation of methylene blue, cardiogreen, and azorubine red dyes upon UV irradiation. The negatively charged crystalline KTiOx nanostructures with high surface area showed significantly higher photocatalytic degradation compared to their TiOx counterpart. They also showed high efficiency for recovery and re-use. Annealing KTiOx nanostructures improved structural properties leading to well-ordered layered structures and improved photocatalysis. However, annealing at temperatures higher than 600 degrees C yielded formation of rutile grains at the surface of nanowires, significantly affecting the photocatalytic performance. We believe that KTiOx nanostructures produced by WCP are very promising for photocatalysis, especially due to their high photocatalytic efficiency as well as their potential for re-use and durability.