Black Titania for Superior Photocatalytic Hydrogen Production and Photoelectrochemical Water Splitting

To utilize visible‐light solar energy to meet environmental and energy crises, black TiO 2 as a photocatalyst is an excellent solution to clean polluted air and water and to produce H 2 . Herein, black TiO 2 with a crystalline core–amorphous shell structure reduced easily by CaH 2 at 400 °C is demonstrated to harvest over 80 % solar absorption, whereas white TiO 2 harvests only 7 %, and possesses superior photocatalytic performances in the degradation of organics and H 2 production. Its water decontamination is 2.4 times faster and its H 2 production was 1.7 times higher than that of pristine TiO 2 . Photoelectrochemical measurements reveal that the reduced samples exhibit greatly improved carrier densities, charge separation, and photocurrent (a 4.5‐fold increase) compared with the original TiO 2 . Consequently, this facile and versatile method could provide a promising and cost‐effective approach to improve the visible‐light absorption and performance of TiO 2 in photocatalysis.