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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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(a) XPS spectra of a α-Fe2O3 nanodisk; (b) high resolution of the Si 2p peak; (c) high resolution of the Fe 2p peak.
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Figure 2: (a) XPS spectra of a α-Fe2O3 nanodisk; (b) high resolution of the Si 2p peak; (c) high resolution of the Fe 2p peak.

Mentions: Even though silicate anions are used in the precursor solution, no diffraction peaks of Si oxide could be observed in any of the XRD patterns due to the small residue of silicate anions in the α-Fe2O3. As examined by XPS, evidence of the existence of Si was obtained, as shown in figure 2(b). Si 2s and Si 2p peaks could be observed in the sample, with a lower binding energy compared with SiO2, indicating the oxygen bridge between Si and Fe atoms, which is consistent with previous reports [28, 34]. The Fe 2p spectrum (figure 2(c)) exhibits the typical 2p1/2 and 2p3/2 peaks of Fe3+ at 724.4 eV and 710.8 eV, with characteristic satellite peaks at 718.8 eV and 732.5 eV [24, 35, 36]. Moreover, the O 1s core levels show dominant oxide peaks at around 531.11 eV, inconsistent with the O2− state [36]. Therefore, it is confirmed that the sample is pure α-Fe2O3 with some Si atoms acting as the oxygen bridges. It is reported that Si [37], Ti [38], Mo [39], Cr [39], and Sn [40] can improve electron-hole separation. With the residual Si in α-Fe2O3, it is reasonable to expect a better photocatalytic performance in dye degradation. Generally, there should be an optimum amount of Si to achieve the best performance. In accordance with this, research into delicate control of the Si in nanodisks is under way.


Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight
(a) XPS spectra of a α-Fe2O3 nanodisk; (b) high resolution of the Si 2p peak; (c) high resolution of the Fe 2p peak.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: (a) XPS spectra of a α-Fe2O3 nanodisk; (b) high resolution of the Si 2p peak; (c) high resolution of the Fe 2p peak.
Mentions: Even though silicate anions are used in the precursor solution, no diffraction peaks of Si oxide could be observed in any of the XRD patterns due to the small residue of silicate anions in the α-Fe2O3. As examined by XPS, evidence of the existence of Si was obtained, as shown in figure 2(b). Si 2s and Si 2p peaks could be observed in the sample, with a lower binding energy compared with SiO2, indicating the oxygen bridge between Si and Fe atoms, which is consistent with previous reports [28, 34]. The Fe 2p spectrum (figure 2(c)) exhibits the typical 2p1/2 and 2p3/2 peaks of Fe3+ at 724.4 eV and 710.8 eV, with characteristic satellite peaks at 718.8 eV and 732.5 eV [24, 35, 36]. Moreover, the O 1s core levels show dominant oxide peaks at around 531.11 eV, inconsistent with the O2− state [36]. Therefore, it is confirmed that the sample is pure α-Fe2O3 with some Si atoms acting as the oxygen bridges. It is reported that Si [37], Ti [38], Mo [39], Cr [39], and Sn [40] can improve electron-hole separation. With the residual Si in α-Fe2O3, it is reasonable to expect a better photocatalytic performance in dye degradation. Generally, there should be an optimum amount of Si to achieve the best performance. In accordance with this, research into delicate control of the Si in nanodisks is under way.

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.


Related in: MedlinePlus