Plasma–induced rapid crystallization and surface engraving of amorphous TiOx(OH)y to enhance adsorption and photocatalytic activity

Abstract

Herein, we highlight a facile, green, and controlled technique commonly known as plasma-liquid interaction for crystal growth, defect engineering, and surface modification of amorphous titanium oxide. Using a novel two-step procedure combining hydrolysis and plasma treatment, we have fabricated defect-enriched anatase TiO2 powder. Rapid crystallization of amorphous titanium oxide is observed due to the interaction of plasma-generated reactive species with the solvated material. However, prolonged treatment time decreases the material's crystallinity due to excess generation of oxygen vacancy defects (OVD) in the TiO2 lattice. The plasma treatment also engraves the material’s surface forming the porous structure, increasing the specific surface area to ∼46 %. At a higher treatment time, TiO2 nanoparticles are grown on the material’s surface. The dye adsorption of the material is quite rapid, and the performance depends on the material’s surface condition. This rapid adsorption speeds up the photo-degradation performance (up to ∼96 %) of the material. The presence of OVD increases the photocatalytic activity of the material. However, an excess amount of OVD quenches the activity. A comparative study between ambient air and argon plasma-assisted material modification for optimized adsorption and photocatalytic performance has been carried out.