Enhanced direct degradation of photogenerated holes induced by dissolved O2 chemisorbed on oxygen-deficient nano-TiO2
Due to the high electronegativity , dissolved O 2 molecules can form strong chemisorption on oxygen-deficient nano-TiO 2 , which can alter the photocatalytic degradation process . Regarding this point, there is a lack of sufficient investigation so far, although there have been many reports on oxygen-deficient nano-TiO 2 . Here, we make the dissolved O 2 adsorbed on the oxygen-deficient nano-TiO 2 by simply stirring for a long time. The characterization and theoretical calculation results show that the chemisorption of O 2 significantly enhances the surface hydrogen bonding and results in a substantial increase in the co-adsorbed H 2 O molecules and –OH groups. The co-chemisorbed oxygen species promote the separation of electron-hole pairs, meanwhile accelerate the migration and accumulation of holes to the surface, which effectively enhances the direct oxidation of photogenerated holes. The findings of this work suggest that for long continuous reactions, the role of chemisorbed dissolved O 2 molecules on the photocatalytic degradation activity of oxygen-deficient nano-TiO 2 has to be considered.
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