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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.


UV/vis DRS spectra of samples synthesized (a) at different temperatures and (b) for different durations at 200 °C. The insets of (a) and (b) show the plots of the (F(R)hv)2 versus photon energy (hv) for the photocatalyst.
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Figure 6: UV/vis DRS spectra of samples synthesized (a) at different temperatures and (b) for different durations at 200 °C. The insets of (a) and (b) show the plots of the (F(R)hv)2 versus photon energy (hv) for the photocatalyst.

Mentions: The high photocatalytic activity is first attributed to the large absorption range of light, which is crucial for good photocatalytic activity, especially for visible-light degradation. Figure 6 shows the UV/Vis DRS of the microwave-synthesized samples and the commercial sample. As shown in figure 6(a), there is a clear red shift of about 10–30 nm in the absorption edge of the microwave-synthesized samples (180 °C and 200 °C) compared with the commercial samples, which is attributed to the multilayer plate structure [43]. The curves of (F(R)hν)2 versus (hv) for the samples are also plotted in the inset of figure 6(a). Through extrapolation of the linear portions of these curves to F(R) = 0, the Eg values of the commercial and microwave samples are obtained and shown in table 1. It is obvious that the Eg of the microwave-synthesized samples is smaller than that of the commercial sample. As a result of a smaller Eg, an extended photoresponse range of approximately 640–670 nm could be achieved, leading to more efficient utilization of the solar spectrum. Thus, the microwave-synthesized samples show significant improvement in MB degradation in the visible-light region. For samples synthesized within 15, 30, and 60 min, the UV/Vis DRS and Eg are similar (figure 6(b) and table 1), indicating that the photocatalytic activities of the samples should be similar. This inference can be confirmed by the MB degradation results (figures 5(e) and (f)). Furthermore, the similarity indicates that these three samples should have almost the same size and structure, which is in good agreement with the SEM and TEM results shown in figures 4(a)–(j).


Facile synthesis of α -Fe 2 O 3 nanodisk with superior photocatalytic performance and mechanism insight
UV/vis DRS spectra of samples synthesized (a) at different temperatures and (b) for different durations at 200 °C. The insets of (a) and (b) show the plots of the (F(R)hv)2 versus photon energy (hv) for the photocatalyst.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: UV/vis DRS spectra of samples synthesized (a) at different temperatures and (b) for different durations at 200 °C. The insets of (a) and (b) show the plots of the (F(R)hv)2 versus photon energy (hv) for the photocatalyst.
Mentions: The high photocatalytic activity is first attributed to the large absorption range of light, which is crucial for good photocatalytic activity, especially for visible-light degradation. Figure 6 shows the UV/Vis DRS of the microwave-synthesized samples and the commercial sample. As shown in figure 6(a), there is a clear red shift of about 10–30 nm in the absorption edge of the microwave-synthesized samples (180 °C and 200 °C) compared with the commercial samples, which is attributed to the multilayer plate structure [43]. The curves of (F(R)hν)2 versus (hv) for the samples are also plotted in the inset of figure 6(a). Through extrapolation of the linear portions of these curves to F(R) = 0, the Eg values of the commercial and microwave samples are obtained and shown in table 1. It is obvious that the Eg of the microwave-synthesized samples is smaller than that of the commercial sample. As a result of a smaller Eg, an extended photoresponse range of approximately 640–670 nm could be achieved, leading to more efficient utilization of the solar spectrum. Thus, the microwave-synthesized samples show significant improvement in MB degradation in the visible-light region. For samples synthesized within 15, 30, and 60 min, the UV/Vis DRS and Eg are similar (figure 6(b) and table 1), indicating that the photocatalytic activities of the samples should be similar. This inference can be confirmed by the MB degradation results (figures 5(e) and (f)). Furthermore, the similarity indicates that these three samples should have almost the same size and structure, which is in good agreement with the SEM and TEM results shown in figures 4(a)–(j).

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.