Mesoporous black N-TiO2-x hollow spheres as efficient visible-light-driven photocatalysts

Mesoporous black N-TiO2-x hollow spheres are successfully fabricated through a facile evaporation induced self-assembly (EISA) process, coupled with an etching procedure and an in-situ solid-state chemical reduction strategy. The resultant black N-TiO2-x hollow spheres with high crystallinity possess a narrow band gap of similar to 2.37 eV, a large specific surface area of similar to 128 m(2) g(-1), and a well defined hollow sphere structure, which exhibit excellent visible-light-driven photocatalytic performance for degradation of phenol, reduction of Cr(IV), and hydrogen production. The photocatalytic reaction apparent rate constants (k) of the black N-TiO2-x for phenol degradation and Cr(IV) reduction are similar to 5 and 6 times higher than that of pristine TiO2, and hydrogen production rate for N-TiO2-x is similar to 160 mu mol h(-1), which is similar to 7 folds higher than that of pristine one. The excellent photocatalytic and photoreduction property can be attributed to the synergy effect of N and Ti3+ codoping narrowing the band gap, the high specific surface area offering more surface active sites, and the mesoporous hollow structure favoring light harvesting and refraction.(C) 2017 Elsevier Inc. All rights reserved.