Photocatalytic Properties of Porous Films Based on α-Fe2O3 Hollow Microspheres
— We have studied photoelectrochemical and photocatalytic properties of porous materials based on hollow α-Fe 2 O 3 microspheres, characterized by the presence of dangling magnetic Fe–O–Fe bonds due to an increased oxygen vacancy concentration on the wall/closed pore interface. Using such powder and...
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Published in | Inorganic materials Vol. 59; no. 3; pp. 272 - 283 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Moscow
Pleiades Publishing
01.03.2023
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | —
We have studied photoelectrochemical and photocatalytic properties of porous materials based on hollow α-Fe
2
O
3
microspheres, characterized by the presence of dangling magnetic Fe–O–Fe bonds due to an increased oxygen vacancy concentration on the wall/closed pore interface. Using such powder and firing slips at an isothermal holding temperature of 400°C, we obtained two series of thin-film samples on glass with a conductive layer from suspensions of two compositions: aqueous Fe(NO
3
)
3
solution + hollow α-Fe
2
O
3
microspheres (series
1
) and aqueous Fe(NO
3
)
3
solution + polyethylene glycol + hollow α-Fe
2
O
3
microspheres (series
2
). The films of series
2
were shown to have a structure with spatially separated particles differing in size: α-Fe
2
O
3
nanoparticles and hollow α-Fe
2
O
3
microspheres. The films of series
1
consisted predominantly of hollow microspheres connected by “necks” formed during heat treatment. The thickness of the films of series
2
was of order 2 μm and that of the films of series
1
was of order 4 μm. The structural distinctions between the films of the two series had a significant effect on the optical properties of the material. In the wavelength range 350–1500 nm, the absorption coefficient of the films of series
2
(3.50 × 10
5
m
–1
) was about twice that of the films of series
1
(1.75 × 10
5
m
–1
). Photoelectrochemical characterization in an aqueous 0.1 M KOH solution showed that the onset potential for the anodic reaction was 0.87 V vs. Ag/AgCl in the case of the films of series
2
and 0.97 V vs. Ag/AgCl in the case of series
1
. The films of both series showed an unusual increase in current density during prolonged illumination at a potential of 1 V vs. Ag/AgCl, due to Fe(IV) formation on the photoanode surface. Photocatalytic properties of the materials were assessed from the rate of methylene blue degradation. The reaction rate constant (
k
) was determined to be 0.015 and 0.018 min
–1
for the films of series
1
and
2
, respectively, whereas the
k
of the photocatalyst-free reaction was 2.8 × 10
–4
min
–1
. |
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ISSN: | 0020-1685 1608-3172 |
DOI: | 10.1134/S0020168523030032 |