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Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight

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ABSTRACT

Intrinsic short hole diffusion length is a well-known problem for α-Fe2O3 as a visible-light photocatalytic material. In this paper, a nanodisk morphology was designed to remarkably enhance separation of electron-hole pairs of α-Fe2O3. As expected, α-Fe2O3 nanodisks presented superior photocatalytic activity toward methylene blue degradation: more than 90% of the dye could be photodegraded within 30 min in comparison with a degradation efficiency of 50% for conventional Fe2O3 powder. The unique multilayer structure is thought to play a key role in the remarkably improved photocatalytic performance. Further experiments involving mechanism investigations revealed that instead of high surface area, ·OH plays a crucial role in methylene blue degradation and that O·2− may also contribute effectively to the degradation process. This paper demonstrates a facile and energy-saving route to fabricating homogenous α-Fe2O3 nanodisks with superior photocatalytic activity that is suitable for the treatment of contaminated water and that meets the requirement of mass production.

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XRD patterns of samples: (a) synthesized at different temperatures; (b) synthesized at 200 °C and different durations.
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Figure 1: XRD patterns of samples: (a) synthesized at different temperatures; (b) synthesized at 200 °C and different durations.

Mentions: The XRD patterns of commercial and synthesized Fe2O3 (140 °C, 160 °C, 180 °C, and 200 °C) are shown in figure 1(a). From the diffraction peaks, it is obvious that as the synthesis temperature increases, the as-synthesized samples change from crystalline to amorphous and then to crystalline again. The observed reflection peaks of the 140 °C sample are in good agreement with the standard pattern of pure FeOOH (JCPDS Card No. 01-0662), whereas the reflection peaks of the 180 °C and 200 °C samples belong to α-Fe2O3 (JCPDS Card No. 24-0072). However, the differences at full-width at half-maximum (FWHM) and relative intensities between the 180 °C and 200 °C samples are apparent. Moreover, compared with the 200 °C sample, the (104) peak is slightly shifted and the (113) peak is missing in the 180 °C sample, suggesting that better crystallinity could be achieved at a higher temperature. According to the well-known Scherrer equation, the average crystallite sizes of 140 °C, 180 °C, and 200 °C were estimated to be 56 nm, 47 nm, and 68 nm, respectively (calculated with the main reflection peak at 2θ = 26.734° for the 140 °C sample, 33.0377° for the 180 °C sample, and 33.0522° for the 200 °C sample; table 1). In order to make a comparison, the particle size of commercial Fe2O3 was also calculated.


Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight
XRD patterns of samples: (a) synthesized at different temperatures; (b) synthesized at 200 °C and different durations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036498&req=5

Figure 1: XRD patterns of samples: (a) synthesized at different temperatures; (b) synthesized at 200 °C and different durations.
Mentions: The XRD patterns of commercial and synthesized Fe2O3 (140 °C, 160 °C, 180 °C, and 200 °C) are shown in figure 1(a). From the diffraction peaks, it is obvious that as the synthesis temperature increases, the as-synthesized samples change from crystalline to amorphous and then to crystalline again. The observed reflection peaks of the 140 °C sample are in good agreement with the standard pattern of pure FeOOH (JCPDS Card No. 01-0662), whereas the reflection peaks of the 180 °C and 200 °C samples belong to α-Fe2O3 (JCPDS Card No. 24-0072). However, the differences at full-width at half-maximum (FWHM) and relative intensities between the 180 °C and 200 °C samples are apparent. Moreover, compared with the 200 °C sample, the (104) peak is slightly shifted and the (113) peak is missing in the 180 °C sample, suggesting that better crystallinity could be achieved at a higher temperature. According to the well-known Scherrer equation, the average crystallite sizes of 140 °C, 180 °C, and 200 °C were estimated to be 56 nm, 47 nm, and 68 nm, respectively (calculated with the main reflection peak at 2θ = 26.734° for the 140 °C sample, 33.0377° for the 180 °C sample, and 33.0522° for the 200 °C sample; table 1). In order to make a comparison, the particle size of commercial Fe2O3 was also calculated.

View Article: PubMed Central - PubMed

ABSTRACT

Intrinsic short hole diffusion length is a well-known problem for α-Fe2O3 as a visible-light photocatalytic material. In this paper, a nanodisk morphology was designed to remarkably enhance separation of electron-hole pairs of α-Fe2O3. As expected, α-Fe2O3 nanodisks presented superior photocatalytic activity toward methylene blue degradation: more than 90% of the dye could be photodegraded within 30 min in comparison with a degradation efficiency of 50% for conventional Fe2O3 powder. The unique multilayer structure is thought to play a key role in the remarkably improved photocatalytic performance. Further experiments involving mechanism investigations revealed that instead of high surface area, ·OH plays a crucial role in methylene blue degradation and that O·2− may also contribute effectively to the degradation process. This paper demonstrates a facile and energy-saving route to fabricating homogenous α-Fe2O3 nanodisks with superior photocatalytic activity that is suitable for the treatment of contaminated water and that meets the requirement of mass production.

No MeSH data available.