J- and H-aggregates of zinc tetraphenylporphyrin (ZnTPP) on carbon nanotube films (CNTFs) were prepared using the mixed solvent method. This resulted in completely different structures, such as the four-leaf clover and flower, on the CNTF, which were observed by recording SEM images. Characteristic changes in the electronic spectra of the ZnTPP monomer appeared when it underwent J- and H-aggregation. The measured photocurrent significantly varied for the same molecule when it was aggregated in two different ways on ITO and ITO/CNTF. The electron recombination resistance of the two aggregates, which was investigated using electrochemical impedance spectroscopy, was also different. The photocatalytic efficiency of the J- and H-aggregates was examined by performing methylene blue dye decoloration studies. In addition, a scanning electrochemical microscope was used to investigate the photoinduced charge transfer kinetics of the J- and H-aggregates at the electrode/electrolyte interface as a fresh attempt. The heterogeneous charge transfer constants for the J- and H-aggregates in the presence of light at varied intensities were calculated. Thereby, striking differences in the photophysical, photocatalytic, and photoelectrochemical properties of the J- and H-aggregates were visualized throughout our studies.
Background
Iron oxide nanocomposites have received a great attention for their application in various fields like physics, medicine, biology, and material science etc., due to their unique properties, such as magnetism, electrical properties, small size, biocompatibility and low toxicity.
Methods
Fe
3
O
4
/Ag
3
PO
4
@WO
3
nanocomposites with different weight percent of Ag
3
PO
4
were successfully prepared through fabricated Ag
3
PO
4
/Fe
3
O
4
with WO
3
via in situ fabrication method, electrospinning involved precursor solution preparation and spinning to enhance photocatalyst performance under simulated sunlight for the degradation of methylene blue (MB) and antibacterial activity against
Staphylococcus aureus
(
S. aureus
).
Results
The photocatalytic degradation of methylene blue (MB) under simulated light irradiation indicated that the nanocomposite with 0.25 mg of Ag
3
PO
4
has the best activity. An additional advantage of these photocatalysts is magnetic recoverability, using external magnetic field and photocatalytic stability of the nanocomposites was evaluated for three cycles. In addition, using different scavengers, holes (h
+
) and superoxide radical (O
2
·−)
radicals and hydroxide radical (
·
OH) were identified the main oxidative species in the degradation reaction of methylene blue.
Conclusions
The results reveal that Fe
3
O
4
/Ag
3
PO
4
@WO
3
-0.25 nanocomposites have photocatalytic and antibacterial activity against
S. aureus.
The photocatalyst and mechanism based on the enhancement of electron transfer processes between Ag
3
PO
4
and WO
3
nanoparticles.
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