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

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.


Fluorescence quenching to detect OH: (a) full wavelength scan of 200/15 sample and (b) different as-synthesized samples.
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Figure 9: Fluorescence quenching to detect OH: (a) full wavelength scan of 200/15 sample and (b) different as-synthesized samples.

Mentions: Due to its unique multilayered structure, electron-hole pairs can separate in an α-Fe2O3 nanodisk more effectively. As a result, enhanced production of ·OH radicals can be expected. As shown in figure 9(a), after 10 min irradiation, the fluorescence intensity of the 200/15 sample obviously increases, indicating increased production of ·OH radicals in the system. In addition, the fluorescence intensity of the ·OH radicals increases with irradiation time, which is consistent with the photocatalytic activity shown in figure 5(d). The fluorescence spectra of other as-synthesized samples are shown in figure 9(b). The order of the ·OH radicals produced is found to be 200/30 > 180/30 ≈ commercial > blank > 160/30, which seems contradictory to the photodegradation results (figure 5(a)). However, recent studies have pointed out that the role of ·OH radicals in photodegradation is probably overestimated [29, 51–54] in terms of other active oxygen species might also be generated during the irradiation process and contribute to photocatalytic degradation. The generation of other active oxygen species might be the reason for this strange phenomenon. In addition, the number of ·OH radicals produced performed a zero-order kinetic model according to a previous study [55]. However, as shown in figure 9(b), the production of ·OH radicals fits with rather a second-order kinetic model as opposed to zero order in this study. Therefore, it is reasonable to assert that other oxygen species might also contribute to dye degradation.


Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight
Fluorescence quenching to detect OH: (a) full wavelength scan of 200/15 sample and (b) different as-synthesized samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: Fluorescence quenching to detect OH: (a) full wavelength scan of 200/15 sample and (b) different as-synthesized samples.
Mentions: Due to its unique multilayered structure, electron-hole pairs can separate in an α-Fe2O3 nanodisk more effectively. As a result, enhanced production of ·OH radicals can be expected. As shown in figure 9(a), after 10 min irradiation, the fluorescence intensity of the 200/15 sample obviously increases, indicating increased production of ·OH radicals in the system. In addition, the fluorescence intensity of the ·OH radicals increases with irradiation time, which is consistent with the photocatalytic activity shown in figure 5(d). The fluorescence spectra of other as-synthesized samples are shown in figure 9(b). The order of the ·OH radicals produced is found to be 200/30 > 180/30 ≈ commercial > blank > 160/30, which seems contradictory to the photodegradation results (figure 5(a)). However, recent studies have pointed out that the role of ·OH radicals in photodegradation is probably overestimated [29, 51–54] in terms of other active oxygen species might also be generated during the irradiation process and contribute to photocatalytic degradation. The generation of other active oxygen species might be the reason for this strange phenomenon. In addition, the number of ·OH radicals produced performed a zero-order kinetic model according to a previous study [55]. However, as shown in figure 9(b), the production of ·OH radicals fits with rather a second-order kinetic model as opposed to zero order in this study. Therefore, it is reasonable to assert that other oxygen species might also contribute to dye degradation.

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.