Synthesis of High-Temperature Stable Anatase TiO2 Photocatalyst
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- 作者：Suresh C. Pillai ; Pradeepan Periyat ; Reenamole George ; Declan E. McCormack ; Michael K. Seery ; Hugh Hayden ; John Colreavy ; David Corr ; Steven J. Hinder
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：February 1, 2007
- 年：2007
- 卷：111
- 期：4
- 页码：1605 - 1611
- 全文大小：124K
- 年卷期：v.111,no.4(February 1, 2007)
- ISSN：1932-7455
文摘
In the absence of a dopant or precursor modification, anatase to rutile transformation in synthetic TiO2 usuallyoccurs at a temperature of 600-700 
C. Conventionally, metal oxide dopants (e.g., Al2O3 and SiO2) are usedto tune the anatase to rutile transformation. A simple methodology is reported here to extend the anataserutile transformation by employing various concentrations of urea. XRD and Raman spectroscopy were usedto characterize various phases formed during thermal treatment. A significantly higher anatase phase (97%)has been obtained at 800 C with use of a 1:1 Ti(OPr)4:urea composition and 11% anatase composition isretained even after calcining the powder at 900 C. By comparison a sample that has been prepared withouturea showed that rutile phases started to form at a temperature as low as 600 C. The effect of smalleramounts of urea such as 1:0.25 and 1:0.5 Ti(OPr)4:urea has also been studied and compared. The investigationconcluded that the stoichiometric modification by urea 1:1 Ti(OPr)4:urea composition is most effective inextending the anatase to rutile phase transformation by 200 C compared to the unmodified sample. In addition,BET analysis carried out on samples calcined at 500 C showed that the addition of urea up to 1:1(Ti(OPr)4:urea) increased the total pore volume (from 0.108 to 0.224 cm3/g) and average pore diameter (11to 30 nm) compared to the standard sample. Samples prepared with 1:1 Ti(OPr)4:urea composition calcinedat 900 C show significantly higher photocatalytic activity compared to the standard sample prepared undersimilar conditions. Kinetic analysis shows a marked increase in the photocatalytic degradation of rhodamine6G on going from the standard sample (0.027 min-1, decoloration in 120 min) to the urea-modified sample(0.073 min-1, decoloration in 50 min).
C. Conventionally, metal oxide dopants (e.g., Al2O3 and SiO2) are usedto tune the anatase to rutile transformation. A simple methodology is reported here to extend the anataserutile transformation by employing various concentrations of urea. XRD and Raman spectroscopy were usedto characterize various phases formed during thermal treatment. A significantly higher anatase phase (97%)has been obtained at 800 C with use of a 1:1 Ti(OPr)4:urea composition and 11% anatase composition isretained even after calcining the powder at 900 C. By comparison a sample that has been prepared withouturea showed that rutile phases started to form at a temperature as low as 600 C. The effect of smalleramounts of urea such as 1:0.25 and 1:0.5 Ti(OPr)4:urea has also been studied and compared. The investigationconcluded that the stoichiometric modification by urea 1:1 Ti(OPr)4:urea composition is most effective inextending the anatase to rutile phase transformation by 200 C compared to the unmodified sample. In addition,BET analysis carried out on samples calcined at 500 C showed that the addition of urea up to 1:1(Ti(OPr)4:urea) increased the total pore volume (from 0.108 to 0.224 cm3/g) and average pore diameter (11to 30 nm) compared to the standard sample. Samples prepared with 1:1 Ti(OPr)4:urea composition calcinedat 900 C show significantly higher photocatalytic activity compared to the standard sample prepared undersimilar conditions. Kinetic analysis shows a marked increase in the photocatalytic degradation of rhodamine6G on going from the standard sample (0.027 min-1, decoloration in 120 min) to the urea-modified sample(0.073 min-1, decoloration in 50 min).