Topics in Current Chemistry (2020) 378:2
1 3
US-irradiated for 8 h showed the highest structural parameters, which were double compared to the white sample (surface area: 329 m
2
/g and total pore volume:
0.251 cm
3
/g).
The evaluation of the photocatalytic capability of the samples was performed by
monitoring the decomposition/removal of acid fuchsin (AF) in aqueous solution.
Since the materials were porous, the removal/reactivity in the dark was evaluated
in detail prior the evaluation of photocatalytic performance. It was found that the
black nanomaterial had an almost three times higher removal capability in the dark
compared than the white one, due to the higher surface area and pore volume. The
analysis of the interactions (by eliminating the effect of physical adsorption) showed
that the US-assisted synthesis led to samples that possess an improved solar- and the
visible-light-driven photocatalytic reactivity. The first-order rate constant obtained
by the Langmuir–Hinshelwood model for the black sample was 5.8 and 7.2 times
higher under solar and visible light irradiation, respectively, compared to the nonUS-treated white sample. The decomposition capability was linked to the formation
of hydroxyl radicals. The fact that the photocatalytic reactivity improvement was
more pronounced in the case of visible light was linked to the enhanced light utilization/harvesting, photo-response range, and the narrowing of the bandgap. Photoluminescence tests showed that the increase of the ultrasonication duration led to
a decrement of the photo-generated electrons and holes pairs, with the latter being
trapped at the disordered phase.
Fig. 8 UV–Vis–IR absorbance spectroscopy (a), valance band XPS spectra (b), and a schematic illustration of density of states (DOS) of the original samples and amorphous hydroxylated samples ultrasonicated for different durations. The blue and black arrows indicate the bandgaps after and before localized
band-bending, respectively. Reprinted with permission from [89]. Copyright (2015) Springer Nature
44
Reprinted from the journal
1 3
US-irradiated for 8 h showed the highest structural parameters, which were double compared to the white sample (surface area: 329 m
2
/g and total pore volume:
0.251 cm
3
/g).
The evaluation of the photocatalytic capability of the samples was performed by
monitoring the decomposition/removal of acid fuchsin (AF) in aqueous solution.
Since the materials were porous, the removal/reactivity in the dark was evaluated
in detail prior the evaluation of photocatalytic performance. It was found that the
black nanomaterial had an almost three times higher removal capability in the dark
compared than the white one, due to the higher surface area and pore volume. The
analysis of the interactions (by eliminating the effect of physical adsorption) showed
that the US-assisted synthesis led to samples that possess an improved solar- and the
visible-light-driven photocatalytic reactivity. The first-order rate constant obtained
by the Langmuir–Hinshelwood model for the black sample was 5.8 and 7.2 times
higher under solar and visible light irradiation, respectively, compared to the nonUS-treated white sample. The decomposition capability was linked to the formation
of hydroxyl radicals. The fact that the photocatalytic reactivity improvement was
more pronounced in the case of visible light was linked to the enhanced light utilization/harvesting, photo-response range, and the narrowing of the bandgap. Photoluminescence tests showed that the increase of the ultrasonication duration led to
a decrement of the photo-generated electrons and holes pairs, with the latter being
trapped at the disordered phase.
Fig. 8 UV–Vis–IR absorbance spectroscopy (a), valance band XPS spectra (b), and a schematic illustration of density of states (DOS) of the original samples and amorphous hydroxylated samples ultrasonicated for different durations. The blue and black arrows indicate the bandgaps after and before localized
band-bending, respectively. Reprinted with permission from [89]. Copyright (2015) Springer Nature
44
Reprinted from the journal