Chemical State and Environment of Boron Dopant in B,N-Codoped Anatase TiO2 Nanoparticles:  An Avenue for Probing Diamagnetic Dopants in TiO2 by Electron Paramagnetic Resonance Spectroscopy

• Published in: Journal of the American Chemical Society Vol. 130; no. 9; pp. 2760 - 2761
• Main Authors: Gopal, Neeruganti O, Lo, Hsin-Hsi, Ke, Shyue-Chu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.03.2008
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/ja711424d

Boron is diamagnetic in B-doped anatase TiO2 nanoparticles which exhibit photocatalytic activities in the visible light range. Using N as a paramagnetic probe for the formal oxidation state of boron in N/B-codoped TiO2, with more than 90% unpaired spin density in the N2p orbital, we infer that boron enters the oxygen vacancy substitutionally in the form of B -. Combination of spin-Hamiltonian analysis and interpretation of light dependent EPR spectra in terms of a charge compensating mechanism supports a model of [N -B1-]+1 for the new EPR active center which acts as a trap for electrons liberated from [N1-] centers under blue light irradiation. Definite assignment of the boron oxidation state will contribute to the preparation, characterization, and understanding of B−TiO2 photoactivity under visible light which has been the subject of extensive work in the past few years.