Synthesis of Mesoporous TiO₂-B Nanobelts with Highly Crystalized Walls toward Efficient H₂ Evolution

Mesoporous TiO₂ is attracting increasing interest due to properties suiting a broad range of photocatalytic applications. Here we report the facile synthesis of mesoporous crystalline TiO₂-B nanobelts possessing a surface area as high as 80.9 m² g^-1 and uniformly-sized pores of 6-8 nm. Firstly, P25 powders are dissolved in NaOH solution under hydrothermal conditions, forming sodium titanate (Na₂Ti₃O₇) intermediate precursor phase. Then, H₂Ti₃O₇ is successfully obtained by ion exchange through acid washing from Na₂Ti₃O₇ via an alkaline hydrothermal treatment. After calcination at 450 °C, the H₂Ti₃O₇ is converted to a TiO₂-B phase. At 600 °C, another anatase phase coexists with TiO₂-B, which completely converts into anatase when annealed at 750 °C. Mesoporous TiO₂-B nanobelts obtained after annealing at 450 °C are uniform with up to a few micrometers in length, 50-120 nm in width, and 5-15 nm in thickness. The resulting mesoporous TiO₂-B nanobelts exhibit efficient H₂ evolution capability, which is almost three times that of anatase TiO₂ nanobelts.