Highly stable visible-light photocatalytic properties of black rutile TiO2 hydrogenated in ultrafast flow

The hydrogenation and introducing oxygen vacancies (VO) can lead to surface lattice disorder in TiO2, which is a new form of TiO2 named black TiO2, with excellent visible-light photocatalytic activity, but this TiO2 is easy to failure because oxidation makes the concentration of surface VO decrease rapidly in a short time. In this work, black TiO2 nanoparticles with VO almost concentrated inside nanoparticles were fabricated under ultrafast hydrogen flow. These bulk VO shortened the bandgaps of black TiO2, enhanced its visible light absorption, and meanwhile provided extremely strong stability. The location of VO in black TiO2 was evident from EPR, XPS with HRTEM investigation, and other characteristics of black TiO2 were obtained by XRD, UV-Vis, SEM, PL, and photocurrent techniques. The degradation experiments on Cr6+ or rhodamine B demonstrated the good visible-light photocatalytic performance of our material. After 18 months of natural aging treatment (in the air), our samples showed no discoloration and maintained 89.5% photocatalytic efficiency, and further study exhibited that this black TiO2 also contained excellent acid resistance and moderate alkaline resistance. This work could help design lattice disorder to obtain more stable and practical black TiO2.