Advanced nanoporous TiO 2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application

We report an effect involving hydrogen (H 2 )-plasma-treated nanoporous TiO 2 (H-TiO 2 ) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO 2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO 2 (a-TiO 2 ) without annealing process. Compared with the a-TiO 2 , the H-TiO 2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H 2 plasma is a simple strategy to fabricate H-TiO 2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO 2 showed strong · OH free-radical generation on the TiO 2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO 2 120(H 2 -plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) — approximately four-times higher than those of the other photocatalysts (a-TiO 2 and P25) — resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO 2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications.