Mesoporous black Ti3+/N-TiO2 spheres for efficient visible-light-driven photocatalytic performance

Mesoporous black Ti 3+ /N-TiO 2 spheres with high crystallinity are fabricated by a facile evaporation-induced self-assembly (EISA) method, using urea as nitrogen resource, combined with a mild calcinations (350   °C) after an in-situ hydrogenation under an argon atmosphere. The prepared materials are characterized by X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results indicate the prepared sample is uniform mesoporous black Ti 3+ /N-TiO 2 spheres with high crystallinity of anatase, high surface area of ∼100   m 2   g −1 , large pore size of 6.5   nm and narrow band gap of 2.11   eV, could be easily controlled with the diameter from 200 to 800   nm. Meanwhile, the photoresponse extends to near-infrared region owing to Ti 3+ and N codoping. The visible-light-driven photocatalytic degradation ratio of methyl orange is up to 96% and photocatalytic hydrogen production rate is ∼150   μmol   h −1 , which are several times higher than that of pristine TiO 2 . Besides, the possible photocatalytic mechanism is proposed. The excellent photocatalytic activity can be ascribed to N and Ti 3+ doping resulting in high visible light utilization and enhanced separation of photogenerated charge carriers, and the mesoporous networks offering more surface active sites.