has a low bandgap of 2.2 eV so that it can absorb visible light within 560 nm,
indicating it can utilize most of the visible light to oxidize organic contaminants.
However, the shortcoming of α-Fe 2 O 3 lies in the high electron–hole recombination
rate and slow conversion of Fe (II) and Fe (III), so the catalytic activity of α-Fe 2 O 3 is
much poor compared to that of γ-Fe 2 O 3 , Fe 3 O 4 , and some other iron catalyst
[49]. Several methods including fabricating composite with carbon material and
forming yolk–shell structure with CdS realized the effective suppression of photogenerated electron and hole of α-Fe 2 O 3 and make it more active in Fenton reaction.
Graphene as a single-layer carbon material has been frequently explored to
prepare composites with α-Fe 2 O 3 as α-Fe 2 O 3 /graphene composites. The large contact interface and strong interaction between graphene and α-Fe 2 O 3 promote the
electron transfer from α-Fe 2 O 3 to graphene, which results in an enhanced
photocatalytic activity. Liu et al. [50] have prepared the composite of α-Fe 2 O 3
anchored on the graphene oxide (GO) nanosheet (α-Fe 2 O 3 /GO) (Fig. 10.2) and
found that the photocatalytic activity of the composite has been enhanced, which
led to approximately 2.9-fold that of classical Degussa P25 TiO 2 and 2.4-fold that of
α-Fe 2 O 3 for the degradation of methylene blue in Photo-Fenton reaction. Guo et al.
[51] have developed a method to synthesize Fe 2 O 3 /GO composite at low temperature (60
C) and found that the degradation rate of Rhodamine B and 4-nitrophenol
was efficiently improved and the catalyst was potential for its good stability, little
iron leaching, simple separation, stable catalytic activity, and wide pH range.
What is further reported is graphene content of the composite, which intensively
influences its photocatalytic activity and other performance. Generally speaking,
there is an optimal value for the composite quantity of graphene. The photocatalytic
activity could be improved using graphene within a certain quantity, but it will
decrease when graphene content is beyond the threshold value through enhancing
absorption and scattering of photons by excess carbon content present in the
composite. Han et al. [52] have explored the photocatalytic activities of the
Table 10.1 (continued)
Photocatalysts Light source
Photocatalytic
application
Photocatalytic activity
enhancement
Reference
ZnFe 2 O 4 /G
Visible light
(λ > 420 nm),
500 W xenon
lamp
Degradation of
MB
–
[73]
ZnFe 2 O 4 /G
Visible light
(λ > 420 nm),
500 W xenon
lamp
Degradation of
RhB, MO, and
MB
–
[74]
α-FeOOH/
RGO
Solar light
Degradation of
phenol
–
[75]
α-FeOOH/
GCA
UV light
(365 nm), 125 W
high-pressure
mercury lamp
Degradation of
MB, RdB, OII,
phenol, and
BPA
–
[76]
10.2 Graphene/Iron (Hydr)oxide Composites Applied in Fenton Reaction
245
indicating it can utilize most of the visible light to oxidize organic contaminants.
However, the shortcoming of α-Fe 2 O 3 lies in the high electron–hole recombination
rate and slow conversion of Fe (II) and Fe (III), so the catalytic activity of α-Fe 2 O 3 is
much poor compared to that of γ-Fe 2 O 3 , Fe 3 O 4 , and some other iron catalyst
[49]. Several methods including fabricating composite with carbon material and
forming yolk–shell structure with CdS realized the effective suppression of photogenerated electron and hole of α-Fe 2 O 3 and make it more active in Fenton reaction.
Graphene as a single-layer carbon material has been frequently explored to
prepare composites with α-Fe 2 O 3 as α-Fe 2 O 3 /graphene composites. The large contact interface and strong interaction between graphene and α-Fe 2 O 3 promote the
electron transfer from α-Fe 2 O 3 to graphene, which results in an enhanced
photocatalytic activity. Liu et al. [50] have prepared the composite of α-Fe 2 O 3
anchored on the graphene oxide (GO) nanosheet (α-Fe 2 O 3 /GO) (Fig. 10.2) and
found that the photocatalytic activity of the composite has been enhanced, which
led to approximately 2.9-fold that of classical Degussa P25 TiO 2 and 2.4-fold that of
α-Fe 2 O 3 for the degradation of methylene blue in Photo-Fenton reaction. Guo et al.
[51] have developed a method to synthesize Fe 2 O 3 /GO composite at low temperature (60
C) and found that the degradation rate of Rhodamine B and 4-nitrophenol
was efficiently improved and the catalyst was potential for its good stability, little
iron leaching, simple separation, stable catalytic activity, and wide pH range.
What is further reported is graphene content of the composite, which intensively
influences its photocatalytic activity and other performance. Generally speaking,
there is an optimal value for the composite quantity of graphene. The photocatalytic
activity could be improved using graphene within a certain quantity, but it will
decrease when graphene content is beyond the threshold value through enhancing
absorption and scattering of photons by excess carbon content present in the
composite. Han et al. [52] have explored the photocatalytic activities of the
Table 10.1 (continued)
Photocatalysts Light source
Photocatalytic
application
Photocatalytic activity
enhancement
Reference
ZnFe 2 O 4 /G
Visible light
(λ > 420 nm),
500 W xenon
lamp
Degradation of
MB
–
[73]
ZnFe 2 O 4 /G
Visible light
(λ > 420 nm),
500 W xenon
lamp
Degradation of
RhB, MO, and
MB
–
[74]
α-FeOOH/
RGO
Solar light
Degradation of
phenol
–
[75]
α-FeOOH/
GCA
UV light
(365 nm), 125 W
high-pressure
mercury lamp
Degradation of
MB, RdB, OII,
phenol, and
BPA
–
[76]
10.2 Graphene/Iron (Hydr)oxide Composites Applied in Fenton Reaction
245