Influence of sulfuric-acid-bath pretreatment and soaked in sulfuric acid on surface morphology and photocatalytic activity of titania coatings

Titania (TiO₂) photocatalyst coatings have been fabricated by the low-cost approach of sulfuric-acid-bath pretreatment (SAP) followed soaked in sulfuric acid (SA) at room temperature then oxidated in air. The influence of the SAP and soaked conditions on the surface morphology and photocatalytic activity of TiO₂ on Ti coatings was investigated. With different SAP conditions, the surface morphologies of the TiO₂ on Ti coatings clearly show the formed porous-like structure. With higher SA concentration, the porous-like structure becomes obviously. With extending soaked time, the porous-like structure tends to disappear. Raman spectroscopy reveals that the formed TiO₂ coatings are with mixed-phase of anatase and rutile. Compared with those of SA concentration and SAP time, the influence of the soaked time on the phase transformation is obvious. Notably, the photocatalytic activity of TiO₂ on Ti coatings had been efficiently enhanced by extending the soaked time, compared with those of higher SA concentration and longer SAP time. The enhanced photocatalytic activity of TiO₂ on Ti coatings could be related with the changed surface morphology, mixed-phase of anatase and rutile, and formed hydroxyl groups.