“…The major peak at 532 nm for pelargonidin chloride corresponds to the HOMO–LUMO gap of 2.33 eV. This value is consistent with the previously reported energy levels of the HOMO (+0.13 V) and LUMO (−2.11 V) relative to standard hydrogen electrode (SHE) for pelargonidin extracted from Ixara Flora . The absorptions for cyanidin (≈543 nm) and delphinidin (553 nm) correspond to the very similar HOMO–LUMO gap values of 2.28 and 2.24 eV, respectively.…”
Section: Resultssupporting
confidence: 89%
“…This value is consistent with the previously reported energy levels of the HOMO (+0.13 V) and LUMO (−2.11 V) relative to standard hydrogen electrode (SHE) for pelargonidin extracted from Ixara Flora. 36 The absorptions for cyanidin (≈543 nm) and delphinidin (553 nm) correspond to the very similar HOMO− LUMO gap values of 2.28 and 2.24 eV, respectively. Conversely, the major peak at 415 nm for the organic dye in PEC-TOM-P04 corresponds to the relatively larger HOMO−LUMO gap of 2.99 eV.…”
Solar
cells and fuel cells are essential devices that convert sustainable
energy into electricity. However, the electromotive forces they provide
are in principle limited to less than 1 V, and consequently, they
need to be connected in series for practical use. In this study, photocatalyst
layers with thicknesses of 0.8–2.1 μm were applied to
both electrodes. The primary particle size of TiO2 was
optimized (15–21 nm), and its performance was further improved
by doping with organic dyes, e.g., anthocyanins. The electron conductivity
of TiO2 was found to be a primary factor in the performance
of the cells, but the film flatness also reduced resistance and improved
cell performance. Interestingly, the efficiency of TiO2 could be evaluated based on the exchangeable surface O atoms via
its 18O2 exchange tests to suppress the reverse
reaction step in water photo-oxidation, which occurs on the anode.
UV and visible light were absorbed by TiO2 and the organic
dyes, respectively, creating an electron flow path from the valence
band to the conduction band of TiO2, then, the highest
occupied molecular orbital (HOMO) to the lowest unoccupied molecular
orbital (LUMO) of the organic dyes, then the anode, and finally the
cathode via the external circuit. The flow of electrons and holes
(separated from electrons in BiOCl on the cathode by UV–visible
light) enabled a V
OC value of 2.11 V and
maximum power of 73.1 μW cm–2.
“…The major peak at 532 nm for pelargonidin chloride corresponds to the HOMO–LUMO gap of 2.33 eV. This value is consistent with the previously reported energy levels of the HOMO (+0.13 V) and LUMO (−2.11 V) relative to standard hydrogen electrode (SHE) for pelargonidin extracted from Ixara Flora . The absorptions for cyanidin (≈543 nm) and delphinidin (553 nm) correspond to the very similar HOMO–LUMO gap values of 2.28 and 2.24 eV, respectively.…”
Section: Resultssupporting
confidence: 89%
“…This value is consistent with the previously reported energy levels of the HOMO (+0.13 V) and LUMO (−2.11 V) relative to standard hydrogen electrode (SHE) for pelargonidin extracted from Ixara Flora. 36 The absorptions for cyanidin (≈543 nm) and delphinidin (553 nm) correspond to the very similar HOMO− LUMO gap values of 2.28 and 2.24 eV, respectively. Conversely, the major peak at 415 nm for the organic dye in PEC-TOM-P04 corresponds to the relatively larger HOMO−LUMO gap of 2.99 eV.…”
Solar
cells and fuel cells are essential devices that convert sustainable
energy into electricity. However, the electromotive forces they provide
are in principle limited to less than 1 V, and consequently, they
need to be connected in series for practical use. In this study, photocatalyst
layers with thicknesses of 0.8–2.1 μm were applied to
both electrodes. The primary particle size of TiO2 was
optimized (15–21 nm), and its performance was further improved
by doping with organic dyes, e.g., anthocyanins. The electron conductivity
of TiO2 was found to be a primary factor in the performance
of the cells, but the film flatness also reduced resistance and improved
cell performance. Interestingly, the efficiency of TiO2 could be evaluated based on the exchangeable surface O atoms via
its 18O2 exchange tests to suppress the reverse
reaction step in water photo-oxidation, which occurs on the anode.
UV and visible light were absorbed by TiO2 and the organic
dyes, respectively, creating an electron flow path from the valence
band to the conduction band of TiO2, then, the highest
occupied molecular orbital (HOMO) to the lowest unoccupied molecular
orbital (LUMO) of the organic dyes, then the anode, and finally the
cathode via the external circuit. The flow of electrons and holes
(separated from electrons in BiOCl on the cathode by UV–visible
light) enabled a V
OC value of 2.11 V and
maximum power of 73.1 μW cm–2.
“…6(A)), indicating a red-shift upon Cr doping. The obtained absorbance values are used to calculate the direct energy band gap of the films using Tauc equation 18,31,32 .where α, A, hʋ and E g correspond to the absorption coefficient, constant, photon energy (eV), and optical band gap, respectively.Figure 6( A ) Absorbance spectra and ( B ) Band gap energy plots for the ZnO (pure) and 0.5 wt% Cr/ZnO NS films.…”
Low power consumption, fast response and quick recovery times are important parameters for gas sensors performance. Herein, we report the experimental and theoretical studies of ZnO and Cr doped ZnO nanostructures used in low temperature (50 °C) sensors for the detection of CO. The synthesized films were characterized by XRD, UV-Vis, FE-SEM and EDX. The XRD patterns for the ZnO and 0.5 wt% Cr/ZnO films confirm the formation of a single-phase hexagonal wurtzite structure. The reduction of the ZnO optical band gap from 3.12 eV to 2.80 eV upon 0.5 wt% Cr doping is well correlated with the simulation data. The FE-SEM images of the films show spherical morphology with the estimated particle sizes of about ~40 nm and ~ 25 nm were recorded for the ZnO and 0.5 wt% Cr/ZnO films, respectively. Enhanced gas sensing performance is achieved with Cr doping and the sensitivity of ZnO increases from 9.65% to 65.45%, and simultaneously decreasing the response and recovery times from 334.5 s to 172.3 s and from 219 s to 37.2 s, respectively. These improvements in gas sensing performance are due to the reduction in particle size and optical band gap, and an increase in specific surface area.
“…They provide an efficiency of around 2 %, sometimes a little higher, but not so much. Researchers are excited to reduce these limitations by modifying several parameters, such as pH modification, [31][32][33] extraction solvents, [34][35][36] cosensitization, [31,37,38] improvement in TiO 2 size, [39][40][41] adjustment of electrolyte structure, [42,43] surface modification, [36,39] reduction of pigment interactions, [44] improvement of TiO 2 soak time in dye solution, [45,46] etc.…”
The rapid growth of the population severely influences the supply of energy, accordingly ensuring clean energy has become a big challenge now and will be in the future. Fossil fuels have been satisfying the energy demand until now, but fossil fuels, being non‐renewable sources, will not be able to satisfy the energy demand in the future and will have a negative impact on the environment. Renewable energy sources have become the most demanding topic for researchers in this crisis. The solar cell, which is an abundant renewable energy resource, converts solar power into electrical energy without any environmental damage. Silicon solar cells have higher efficiency, but their high manufacturing cost, complicated procedures and environmental issues restrict their usage. Then dye‐sensitized solar cells (DSSCs) have been introduced as an alternative to silicon solar cells. In DSSC, both natural and synthetic dyes are used. Though synthetic dyes provide higher efficiency, they are environmentally harmful. Afterward, the concept of natural dye‐sensitized solar cells (NDSSC) have been materialized where only natural dyes are used. Researchers and environmentalists are looking for natural dyes as a replacement for synthetic dyes in recent times, as natural dyes are plentiful, can be collected naturally and have no environmental effects. Natural dyes in the form of anthocyanins, carotenoids, flavonoids, chlorophylls, tannins and betalains are extracted from various portions of plants that include leaves, roots, flowers, fruits, seeds, barks, etc. In this review, we investigate natural sources of dyes, natural sensitizers (dyes), shortcomings and remedies, improvements in efficiency and stability, developments, and commercialization. In addition, recent advances and the comparison of natural and synthetic dyes have been discussed in this review.
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