title: 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.
abstract: 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 B1-. Combination of spin-Hamiltonian analysis and interpretation of light dependent EPR spectra in terms of a charge compensating mechanism supports a model of [N2-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.
authors.affiliation: Physics Department and Nanotechnology Research Center, National Dong Hwa University, Hualien, Taiwan 974-01.
authors.forename: Neeruganti O
authors.initials: NO
authors.lastname: Gopal
authors.forename: Hsin-Hsi
authors.initials: HH
authors.lastname: Lo
authors.forename: Shyue-Chu
authors.initials: SC
authors.lastname: Ke