In situ FT-IR Studies of Photocatalytic CO2 Reaction on Photocatalysts
Date Issued
2006
Date
2006
Author(s)
Huang, Chao-Wei
DOI
zh-TW
Abstract
Photocatalytic CO2 reaction on TiO2 and transition metal-loaded TiO2 (Cu/TiO2) catalysts under UV irradiation was studied using in situ FT-IR spectroscopy. TiO2 and Cu/TiO2 catalysts were prepared by sol-gel method via controlled hydrolysis of titanium (Ⅳ) butoxide. Copper was loaded onto TiO2 during sol-gel procedure. XRD and UV-Visible tests showed that the structures and the abilities of absorbing UV light.
After treated at 500℃under air flow, a large amount of surface peroxo species and OH groups were detected on the TiO2 and Cu/TiO2 catalysts. Under CO2 flow, CO2 removed original H2O and OH groups on the surface of catalysts and formed carbonate as well as bicarbonate expeditiously via CO2 combining with oxygen-vacancy and OH groups respectively.
Under UV irradiation, photogenegrated holes merged with OH- from H2O dissociation to form OH groups and combined with O2- of TiO2 to form disorbing O2 and oxygen-vacancy. CO2 combined with oxygen-vacancy and OH groups generated from UV irradiation to form carbonate or bicarbonate newly as CO2 in the adsorption sort decreased. Photogenerated electron merged with H+ from H2O dissociation to from H atom which reduced CO2 to formate, formic acid, dioxymethlene species, formaldehyde and methoxy slightly using in situ FT-IR spectroscopy. The IR signals of reduced products are weak. It is inferable that the efficiency of photocatalytic reduction and reaction mechanism is not easy to observe.
Based on the FT-IR result, Photocatalytic CO2 reduction were not apparent. A possible mechanism is proposed for the photocatalytic CO2 reduction on photocatalysts from the weak signals of in situ FT-IR detecting the reduced intermediates and products on the photocatalysts.
Subjects
紅外線偵測
二氧化碳
光觸媒
光催化反應
in situ FT-IR
carbon dioxide
photocatalysts
photocatalytic
Type
thesis
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