S.Y. Lee, J.W. Seo
Shibaura Institute of Technology, Japan,
Japan
Keywords: nanoparticles, nanostructures, wet corrosion process, Ti, photocatalysis
Summary:
Up to date, nanostructured Ti-based materials have attracted considerable attention due to their unique and diverse physico-chemical properties and potential for diverse applications. Among them, nanostructured potassium (K) incorporated Ti-based oxide materials (KTiOx) have received particular attention due to their wide range of interesting applications, e.g. in photovoltaic cells, photocatalysis, gas sensors, biomaterials, owing to their remarkable structural and physical properties. However, so far one of the main bottlenecks for diverse applications has been the nanostructures fabrication, which generally involves complicated process, low reproducibility and high cost for chemical modification. Since the physical properties can be greatly affected by the size and morphology of the nanostructures as well as the precise incorporated K amount, several processes had to be combined, exacerbating these drawbacks. Despite great expectations, there is still a lack of systematic research and strategy for nanostructures fabrication while simultaneously controlling the physical properties, resulting in limitation of their fast implementation in potential applications. Hence, elaborating a process that allows easy synthesis and a simple tuning of the desired morphology and properties via a single-step process is currently one of the key issues in this research field. We used the wet corrosion process (WCP) which was developed in my previous research to Ti metal plates. In this work, we extended our studies to Ti-based particles and systematically investigated, for the first time, the characteristics of the resulting KTiOx nanowires. The results clearly indicate optical properties of the KTiOx nanowires could be correlated with their structural properties. Ti-based materials are currently considered as one of the most promising candidates for multifunctional semiconductor photocatalysts as eco-friendly alternative technology because of their chemical and biological inertness, photostability and low cost of production. We have investigated the photocatalytic performance of KTiOx fabricated by WCP. This result can be very interesting for treating water containing organics, removing metals from water and splitting water. We performed a detailed structural and chemical analysis of KTiOx nanostructures produced by the WCP of Ti microspheres. The KTiOx nanowires obtained from 15 mol/L KOH solution yielded the highest surface area and also the highest photocatalytic performance. The KTiOx nanostructures which were annealed at 600°C showed the highest photocatalytic degradation of 92% for MB dye, 99% for CG dye, and 33% for AR dye. This result was attributed to the enhanced active surface area as well as the presence of the crystalline layered structure based on the anatase phase. In addition, the KTiOx nanostructures immobilized on Ti particles offer great advantages for separation from the liquid. Indeed, remarkable recycling performance of 97% for MB dye, 71% for CG dye, and 67% AR dye was obtained after simply washing with deionized water and with organic solvents. We believe that the KTiOx nanostructures produced by the WCP has a great potential for photocatalysis where high catalytic activity and easy cleaning are required.