Nanoporous hydrogenated TiO2 photocatalysts generated by underwater discharge plasma treatment for solar photocatalytic applications

Abstract In this paper, we report on the mass production, characteristics and application of a hydrogenated TiO 2 photocatalyst (H-TiO 2 ) with high reactivity under solar light irradiation. The H-TiO 2 photocatalyst has been prepared by simple sol-gel method/underwater discharge plasma treatment at room temperature and atmospheric pressure. The optical absorption spectrum of TiO 2 can be extended from the ultraviolet (UV) into the visible range by changing the surface properties. The crystallinity, hydrogenation and porosity of TiO 2 can be greatly enhanced within 90 s through underwater discharge plasma, using amorphous TiO 2 (as-synthesized TiO 2 , a-TiO 2 ) as the precursor. The resultant H-TiO 2 showed high bicrystalline (anatase/brookite phases) and a large surface area (267.5 m 2 /g), thus improving photocatalytic activity. We have demonstrated that H-TiO 2 showed significant photocatalytic efficiencies for degradation of reactive black 5, rhodamine B, and phenol under solar light irradiation, up to 10 times higher than those of commercial TiO 2 and a-TiO 2 , leading to complete water purification. Interestingly, the H-TiO 2 photocatalyst also exhibited strong antimicrobial activities against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus under solar light irradiation, up to 5-times greater than those of commercial TiO 2 and a-TiO 2 . Given that H-TiO 2 can be mass produced and easily processed by underwater discharge plasma, we expect this plasma technology may find important environmental and medical applications.