To date, Ti-based nanostructures have attracted a considerable amount of attention in photocatalysis, phtovoltaics, electrochromic devices, electrochemistry, biointerfaces and corrosion because of their unique and diverse physico-chemical properties. Among them, potassium (K) incorporated Ti-based nanostructured oxides (KTiOx) have received particular attention due to their wide range of applications as previously mentioned and because of their remarkable structure. KTiOx materials are versitle, and through control of the K content, the electrical and optical properties can be fine-tuned. Moreover, whereas other metal oxide particles for photocataysis such as CdS or GaP degrade and produce toxic end-products, the catalytic activity of KTiOx only involves photoenergy without additional chemicals, resulting in an environmentally friendly product. One of the main bottlenecks in using KTiOx for diverse applications is the nanostructures fabrication, which generally involves a complicated process with low reproducibility and high cost of chemical modifications. The physical properties of KTiOxs which are made by chemical modification greatly affected by the incopoarated K in the obtained KTiOxs, thereby inducing the various the size and morphology of the nanostructures. On the basis of this result, the precious amount of the incopoarated K is a key issue to control the desirable porpperites. Herein, the development of a process that allows simple synthesis and tuning of the desired morphology and properties is currently an important roadblock in this research field.
In this contribution, KTiOx nanowires were prepared by wet corrosion process (WCP) and had their photocatalytic effects systematically characterized. In the synthesis of the KTiOxs, the potassium hydroxide (KOH) concentrations were varied durnig the WCP in order to obtain nanostructures with different surface areas and surface charges. Structural and crystalline properties of the KTiOxs were studied by means of X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Chemical composition was determined through 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. Note that the heat treatment was carried out to increase the crystallinity of KTiOxs. The results demonstrated that the negatively charged crystalline KTiOx nanostructures with high surface area showed significantly higher photocatalytic degradation when compared to KTiOxs with low crystallinity. The produced KTiOxs also showed greater efficiency for recovery and re-use. The heat treatment belowe 600 °C yielded nanostructures with improved structural properties, leading to well organized, layered structures with improved photocatalysis. We believe that KTiOx nanostructures produced by WCP are very promising for photocatalysis, due to their high photocatalytic efficiency and potential for high re-useablility.