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Synthesis of Cu2O Nanospheres Decorated with TiO2 Nanoislands, Their Enhanced Photoactivity and Stability under Visible Light Illumination, and Their Post-illumination Catalytic Memory
journal contribution
posted on 2014-04-23, 00:00 authored by Lingmei Liu, Weiyi Yang, Qi Li, Shian Gao, Jian Ku ShangA novel Cu2O/TiO2 composite photocatalyst
structure of Cu2O nanospheres decorated with TiO2 nanoislands were synthesized by a facile hydrolyzation reaction
followed by a solvent-thermal process. In this Cu2O/TiO2 composite photocatalyst, Cu2O served as the main
visible light absorber, while TiO2 nanoislands formed heterojunctions
of good contact with Cu2O, beneficial to the photoexcited
electron transfer between them. Their band structure match and inner
electrostatic field from the p–n heterojunction both favored the transfer of photoexcited electrons
from Cu2O to TiO2, which effectively separated
the electron–hole pairs. Photogenerated holes on Cu2O could react with water or organic pollutants/microorganisms in
water to avoid accumulation on Cu2O because of the partial
TiO2 nanoislands coverage, which enhanced their stability
during the photocatalysis process. Their superior photocatalytic performance
under visible light illumination was demonstrated in both the degradation
of methyl orange and the disinfection of Escherichia coli bacteria. An interesting post-illumination catalytic memory was
also observed for this composite photocatalyst as demonstrated in
the disinfection of Escherichia coli bacteria in
the dark after the visible light was shut off, which could be attributed
to the transfer of photoexcited electrons from Cu2O to
TiO2 and their trapping on TiO2 under visible
light illumination, and their release in the dark after the visible
light was shut off.