Hydrogenated blue titania with high solar absorption and greatly improved photocatalysis

Abstract

Hydrogenated black titania, with a crystalline core/amorphous shell structure, has attracted global interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships remains a great challenge and a more effective method to produce hydrogenated titania is desirable. Herein, we report a TiH₂ assisted reduction method to synthesize bluish hydrogenated titania (TiO_2−x:H) that is highly crystallized. The characteristic amorphous shells, which are essential for the enhancement of solar absorption and photocatalysis in many reported hydrogenated titania, are completely removed by hydrogen peroxide. The blue TiO_2−x:H sample without amorphous shells delivers not only significantly improved visible- and infrared-light absorption but also greatly enhanced photocatalytic activity compared to pristine TiO₂. Its water decontamination is 2.5 times faster and the hydrogen production was 1.9-fold higher over pristine TiO₂. Photoelectrochemical measurement reveals greatly improved carrier density and photocurrent (a 4.3-fold increase) in the reduced TiO_2−x:H samples. This work develops a facile and versatile method to prepare hydrogenated titania and proposes a new understanding of the hydrogenated titania that doped hydrogen atoms, instead of the amorphous shells, are essential for its high photocatalytic performance.