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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.

No MeSH data available.


EIS changes in α-Fe2O3 nanodisk and commercial sample electrodes.
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Figure 8: EIS changes in α-Fe2O3 nanodisk and commercial sample electrodes.

Mentions: Because of the intrinsic short hole diffusion length (2–4 nm) [17, 18], photogenerated electron-hole pairs in α-Fe2O3 cannot be easily separated, resulting in an unsatisfied photocatalytic performance in some samples (140 °C, 160 °C, 180 °C, and commercial). However, the α-Fe2O3 nanodisk is combined with a few nanoplates with a thickness around 3–6 nm (figure 4). As a result of the thin-layered structure, electron-hole pairs can separate and participate in the photo-oxidation process on the surface more effectively. To further confirm the effective separation of electron-hole pairs in the α-Fe2O3 nanodisk, EIS was conducted, as shown in figure 8. Only one semicircle was observed on the EIS plane, suggesting that the photocatalytic reaction involved only the surface charge-transfer process. The semicircle radius of the α-Fe2O3 nanodisk electrode is much smaller than that of the commercial sample, indicating a decrease in the solid-state interface layer resistance. This leads to a higher transfer rate of the electron-hole pairs [44]. As a result, aggregation of the electrons is alleviated, thus reducing their recombination rate. The separation and transmission of electron-hole pairs should be improved, which is crucial to photocatalytic performance [45]. Furthermore, the residual Si as dopant may also improve the photoelectrolysis and electrical properties [37], another potential factor in high photocatalytic activity. Therefore, an α-Fe2O3 nanodisk with a thin-layer structure presents high photocatalytic activity.


Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight
EIS changes in α-Fe2O3 nanodisk and commercial sample electrodes.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: EIS changes in α-Fe2O3 nanodisk and commercial sample electrodes.
Mentions: Because of the intrinsic short hole diffusion length (2–4 nm) [17, 18], photogenerated electron-hole pairs in α-Fe2O3 cannot be easily separated, resulting in an unsatisfied photocatalytic performance in some samples (140 °C, 160 °C, 180 °C, and commercial). However, the α-Fe2O3 nanodisk is combined with a few nanoplates with a thickness around 3–6 nm (figure 4). As a result of the thin-layered structure, electron-hole pairs can separate and participate in the photo-oxidation process on the surface more effectively. To further confirm the effective separation of electron-hole pairs in the α-Fe2O3 nanodisk, EIS was conducted, as shown in figure 8. Only one semicircle was observed on the EIS plane, suggesting that the photocatalytic reaction involved only the surface charge-transfer process. The semicircle radius of the α-Fe2O3 nanodisk electrode is much smaller than that of the commercial sample, indicating a decrease in the solid-state interface layer resistance. This leads to a higher transfer rate of the electron-hole pairs [44]. As a result, aggregation of the electrons is alleviated, thus reducing their recombination rate. The separation and transmission of electron-hole pairs should be improved, which is crucial to photocatalytic performance [45]. Furthermore, the residual Si as dopant may also improve the photoelectrolysis and electrical properties [37], another potential factor in high photocatalytic activity. Therefore, an α-Fe2O3 nanodisk with a thin-layer structure presents high photocatalytic activity.

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.