Photo-induced hydrophilicity of brookite TiO₂ prepared by hydrothermal conversion from Mg₂TiO₄

Abstract

Super-hydrophilic titanium dioxide (TiO 2 ) photocatalysts with some mild oxidizing ability are favorable for the self-cleaning applications on plastic films. In this study, we have focused on brookite TiO 2 for such purposes. Brookite TiO 2 powders were synthesized by the hydrothermal conversion method using Mg 2 TiO 4 as a precursor. Mg 2 TiO 4 (1 g) and 1 M HCl (30 mL) were put into a polytetrafluoroethylene (PTFE)-lined autoclave. The hydrothermal conversion was conducted at 110150°C for 24 h. The photocatalytic oxidizing properties of brookite TiO 2 /silicone films on glass substrates, prepared by the flow-coating method, were measured by methylene blue decomposition, and the photo-induced hydrophilicizing properties were evaluated using the contact angle of water under UV irradiation. The brookite TiO 2 /silicone film prepared from the sample treated at 150°C exhibited well-balanced properties for self-cleaning applications.

Facile synthesis of > 99% phase-pure brookite TiO2 by hydrothermal conversion from Mg2TiO4

“…In our previous study [8], we reported that the excessive oxidizing ability of anatase TiO 2 caused some problems in the self-cleaning; it formed CaSO 4 white precipitates on a window from atmospheric pollutants. Hence, in our recent study [9], we have focused on brookite TiO 2 with a mild oxidizing ability, which is suitable for the self-cleaning.…”

“…It is practical to obtain brookite TiO 2 powder, but its phase purity is not as prominent as the Tomita method [13]. In our recent work on the self-cleaning [9], we have synthesized brookite powders via the Kozawa method. Actually, the obtained TiO 2 was a mixture of brookite and rutile, and the highest purity of brookite was 97.2 wt % [9].…”

“…In our recent work on the self-cleaning [9], we have synthesized brookite powders via the Kozawa method. Actually, the obtained TiO 2 was a mixture of brookite and rutile, and the highest purity of brookite was 97.2 wt % [9]. Such residual rutile TiO 2 can be also seen in the original report by Kozawa et al (Fig.…”

Estudo da atividade fotocatalítica de filmes de TiO₂ dopados com enxofre

“…As propriedades auto-limpantes do dióxido de titânio têm sido amplamente pesquisadas por diversos segmentos industriais 53,54 , principalmente em tecnologias de recobrimento em vidros de janelas e em tecidos 55 . Outros estudos abordam seu caráter super-hidrofílico, isto é, superfície polar capaz de absorver a água, ou super-hidrofóbico, que repele a água 56 .…”

“…A formação de filmes finos pode ser dividida em duas classes . As técnicas magnetron sputtering, método hidrotérmico, solvotérmico, e oxidação por micro-arco também têm sido utilizadas 15,17,53,56 . Na Fig.…”