Journal
ACS NANO
Volume 9, Issue 10, Pages 10482-10488Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.5b04712
Keywords
black TiO2; nanoparticles; TEM characterization; core-shell structure; nonstoichiometry; reduced band-gap
Categories
Funding
- Materials Sciences and Engineering Division, Basic Energy Sciences, Office of Science, U.S. Department of Energy
- Oak Ridge National Laboratory by the Scientific User Facilities Division, U.S. Department of Energy
- Office of Science of the US DOE [DE-AC02-05CH11231]
Ask authors/readers for more resources
The remarkable properties of black TiO2 are due to its disordered surface shell surrounding a crystalline core. However, the chemical composition and the atomic and electronic structure of the disordered shell and its relationship to the core remain poorly understood. Using advanced transmission electron microscopy methods, we show that the outermost layer of black TiO2 nano-particles consists of a disordered Ti2O3 shell. The measurements show a transition region that connects the disordered Ti2O3 shell to the perfect rutile core consisting first of four to five monolayers of defective rutile, containing clearly visible Ti interstitial atoms, followed by an ordered reconstruction layer of Ti interstitial atoms. Our data suggest that this reconstructed layer presents a template on which the disordered Ti2O3 layers form by interstitial diffusion of Ti ions. In contrast to recent reports that attribute TiO2 band-gap narrowing to the synergistic action of oxygen vacancies and surface disorder of nonspecific origin, our results point to Ti2O3, which is a narrow-band-gap semiconductor. As a stoichiometric compound of the lower oxidation state Ti3+ it is expected to be a more robust atomic structure than oxygen-deficient TiO2 for preserving and stabilizing Ti3+ surface species that are the key to the enhanced photocatalytic activity of black TiO2.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available