Helical Anatase Titanium Nanotubes through a Protected Crystallization Strategy for Enhanced Photocatalytic Performance

Helical structure in catalysts has attracted attention and been recently investigated for various catalytic reactions. However, helical transition metal oxides suffer from uncontrollable crystallization processes at high temperatures when being transformed from an amorphous phase into a crystalline structure. Herein, we report a helical anatase TiO₂ nanotube for the first time, which has been prepared using a protected crystallization strategy in the confined space of silica. A single chirality of helical TiO₂ has been used to track the ordering of the twisted structure. The twisted structure in helical anatase TiO₂ nanotube is maintained after a vigorous crystallization process. Helical anatase TiO₂ nanotubes possess more accessible active sites and abundant defects of oxygen vacancy and Ti³⁺ species owing to the twisted structure. The obtained helical anatase TiO₂ nanotube exhibits superior photocatalytic activity for hydrogen production without adding any co-catalysts. This work provides new insights into the role of helical structure in transition metal-based catalysts.