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

Potassium doped titanium oxide (KTiO x ) nanowires were prepared by the wet corrosion process (WCP) and their photocatalytic effects were systematically characterized. For the synthesis of KTiO x , the potassium hydroxide concentration of the WCP was varied in order to obtain nanostructures with different surface area and surface charge. Structural and crystalline properties of KTiO x 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 KTiO x nanostructures with high surface area showed significantly higher photocatalytic degradation compared to their TiO x counterpart. They also showed high efficiency for recovery and re-use. Annealing KTiO x nanostructures improved structural properties leading to well-ordered layered structures and improved photocatalysis. However, annealing at temperatures higher than 600 °C yielded formation of rutile grains at the surface of nanowires, significantly affecting the photocatalytic performance. We believe that KTiO x 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.