RT info:eu-repo/semantics/article
T1 Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity
A1 Kumaravel, Vignesh
A1 Rhatigan, Stephen
A1 Mathew, Snehamol
A1 Michel, Marie Clara
A1 Bartlett, John
A1 Nolan, Michael
A1 Hinder, Steven J.
A1 Gasco Guerrero, Antonio María
A1 Ruiz Palomar, César
A1 Hermosilla Redondo, María Daphne
A1 Pillai, Suresh C.
K1 Photocatalysis
K1 Nanoscience
K1 Nanotechnology
K1 TiO2
AB This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO2. Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO2 (Mo–TiO2). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750 °C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti–O bond. The formation of Ti–O–Mo and Mo–Ti–O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo–TiO2 through oxygen vacancy formation. Mo5+ and Ti3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron–hole recombination process in Mo–TiO2 was exceptionally lower than that of TiO2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO2 surface by Mo6+ and Mo5+ ions to improve the photocatalytic activity.
PB IOP Publishing
SN 2515-7639
YR 2020
FD 2020
LK https://uvadoc.uva.es/handle/10324/57514
UL https://uvadoc.uva.es/handle/10324/57514
LA eng
NO Journal of Physics: Materials, 2020, Vol. 3, Nº. 2, 025008
NO Producción Científica
DS UVaDOC
RD 11-jul-2024