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Photochem
Number of Followers: 19  Open Access journalISSN (Online) 2673-7256 Published by MDPI  [258 journals]
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- Photochem, Vol. 4, Pages 285-301: A Systematic Review of Heterogeneous
Catalysis Applied to the Treatment of Pharmaceutical Wastewater:
Operational Conditions and Statistical Analysis
Authors: Raqueline Caldas do Nascimento, Arthur Cahino, Larissa Granjeiro Lucena, Inalmar D. Barbosa Segundo, Jonathan Cawettiere Espíndola, Elisângela M. R. Rocha
First page: 285
Abstract: The use of heterogeneous photocatalysis has garnered significant attention, mainly due to its remarkable efficacy in degrading recalcitrant compounds. The main objective of this research was to investigate this process applied to pharmaceutical treatment. For that, an analysis of a Final Bibliographic Portfolio (FBP), using the systematic review of the PRISMA and the ProKnow-C method, and a meta-analysis study in a historical series from 2010 to 2020, were performed for scientific works published in indexed journals from the Scopus and Web of Science databases and fully available in English. The works were filtered after a careful reading of the titles, followed by the exclusion of repeated documents and those that were not aligned with the research from 3498 articles, 40 of which were chosen to compose the FBP that addressed the classes of antibiotics, antihypertensives, analgesics, and anti-inflammatory drugs after scientific recognition and exclusion due to not fitting into one of the four FBP structured stages: (1) identification, (2) triage, (3) eligibility, and (4) inclusion. The following gaps were highlighted: (i) a limited number of studies working with interactions of the interfering variables; (ii) a large number of experiments not considering the natural constituents of wastewater; (iii) the use of drug concentrations high above the values found in aquatic matrices; (iv) little applicability of the process at the real scale. In this meta-analysis study, operational parameter optimization was fundamental to guarantee degradation efficiencies above 80% with a variety of pharmaceutical pollutants, the main representatives studied of which were tetracycline, nimesulide, diclofenac, ibuprofen, and atenolol. However, there is still a need to determine the best conditions for this technique when using real effluents, which have the utmost importance for the process on a large scale.
Citation: Photochem
PubDate: 2024-06-29
DOI: 10.3390/photochem4030017
Issue No: Vol. 4, No. 3 (2024)
- Photochem, Vol. 4, Pages 302-318: Synthesis of Metallic and Metal Oxide
Nanoparticles Using Homopolymers as Solid Templates: Luminescent
Properties of the Eu+3 Nanoparticle Products
Authors: María Ángeles Cortés, Carlos Díaz, Raquel de la Campa, Alejandro Presa-Soto, María Luisa Valenzuela
First page: 302
Abstract: Starting from poly(4-vinylpyridine) ((P4VP)n), poly(2-vinylpyridine) ((P2VP)n), and [N=P(O2CH2CF3)]m-b-P2VP20 block copolymers, a series of metal-containing homopolymers, (P4VP)n⊕MXm, (P2VP)n⊕MXm, and [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm MXm = PtCl2, ZnCl2, and Eu(NO3)3, have been successfully prepared by using a direct and simple solution methodology. Solid-state pyrolysis of the prepared metal-containing polymeric precursors led to the formation of a variety of different metallic and metal oxide nanoparticles (Pt, ZnO, Eu2O3, and EuPO4) depending on the composition and nature of the polymeric template precursor. Thus, whereas Eu2O3 nanostructures were obtained from europium-containing homopolymers ((P4VP)n⊕MXm and (P2VP)n⊕MXm), EuPO4 nanostructures were achieved using phosphorus-containing block copolymer precursors, [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm with MXm = Eu(NO3)3. Importantly, and although both Eu2O3 and EuPO4 nanostructures exhibited a strong luminescence emission, these were strongly influenced by the nature and composition of the macromolecular metal-containing polymer template. Thus, for P2VP europium-containing homopolymers ((P4VP)n⊕MXm and (P2VP)n⊕MXm), the highest emission intensity corresponded to the lowest-molecular-weight homopolymer template, [P4VP(Eu(NO3)3]6000, whereas the opposite behavior was observed when block copolymer precursors, [N=P(O2CH2CF3)]m-b-P2VP20]⊕MXm MXm= Eu(NO3)3, were used (highest emission intensity corresponded to [N=P(O2CH2CF3)]100-b-[P2VP(Eu(NO3)3)x]20). The intensity ratio of the emission transitions: 5D0 → 7F2/5D0 → 7F1, suggested a different symmetry around the Eu3+ ions depending on the nature of the polymeric precursor, which also influenced the sizes of the prepared Pt°, ZnO, Eu2O3, and EuPO4 nanostructures.
Citation: Photochem
PubDate: 2024-07-14
DOI: 10.3390/photochem4030018
Issue No: Vol. 4, No. 3 (2024)
- Photochem, Vol. 4, Pages 319-333: Facile Doping of 2,2,2-Trifluoroethanol
to Single-Walled Carbon Nanotubes Electrodes for Durable Perovskite Solar
Cells
Authors: Naoki Ueoka, Achmad Syarif Hidayat, Hisayoshi Oshima, Yoshimasa Hijikata, Yutaka Matsuo
First page: 319
Abstract: Perovskite solar cells with an indium tin oxide (ITO)/SnO2/CH3NH3PbI3/Spiro-OMeTAD/2,2,2-trifluoroethanol (TFE) doped single-walled carbon nanotube (SWCNT) structure were developed by dropping TFE onto SWCNTs, which replaced the metal back electrode, and a conversion efficiency of 14.1% was achieved. Traditionally, acidic doping of the back electrode, SWCNT, has been challenging due to the potential damage it may cause to the perovskite layer. However, TFE has facilitated easy doping of SWCNT as the back electrode. The sheet resistance of the SWCNTs decreased and their ionization potential shifted to deeper levels, resulting in improved hole transport properties with a lower barrier to carrier transport. Furthermore, the Seebeck coefficient (S) increased from 34.5 μV/K to 73.1 μV/K when TFE was dropped instead of EtOH, indicating an enhancement in the behavior of p-type charge carriers. It was observed that hydrophilic substances adhered less to the SWCNT surface, and the formation of PbI2 was suppressed. These effects resulted in higher conversion efficiency and improved solar cell performance. Furthermore, the decrease in conversion efficiency after 260 days was suppressed, showing improved durability. The study suggests that combining SWCNTs and TFEs improves solar cell performance and stability.
Citation: Photochem
PubDate: 2024-07-14
DOI: 10.3390/photochem4030019
Issue No: Vol. 4, No. 3 (2024)
- Photochem, Vol. 4, Pages 334-345: Optimization of CdSe Thin-Film
Photoelectrochemical Cells: Effects of NaOH/Na2S/S Redox Couple
Concentration and Activity on Cell Efficiency
Authors: Ahed H. Zyoud
First page: 334
Abstract: This study investigates the relationships among redox couple activity, electrolyte concentration, and efficiency in CdSe thin-film photoelectrochemical solar cells. A CdSe photo-electrode was prepared using the electro-depositing technique to produce well-staged layering of CdSe, followed by chemical bath deposition to produce a layer with an acceptable thickness to absorb enough photons to create a suitable amount of photocurrent. The CdSe photo-electrochemical cell was tested under various concentrations of a NaOH/Na2S/S electrolyte solution. The results showed that the activity of the redox couple greatly affected the efficiencies of the solar cells. Correlation plots between ionic strength and PEC efficiency with the Debye–Hückel equation yielded an R² value of 0.96, while those between ionic strength and photocurrent density had an R² value of 0.92. The correlation between concentration and PEC efficiency was much weaker. This paper highlights how optimal ionic activity increases the performance of photoelectrochemical solar cells, which consequently improves the conversion efficiency of solar energy.
Citation: Photochem
PubDate: 2024-08-10
DOI: 10.3390/photochem4030020
Issue No: Vol. 4, No. 3 (2024)
- Photochem, Vol. 4, Pages 151-162: Charge-Selective Photocatalytic
Degradation of Organic Dyes Driven by Naturally Occurring Halloysite
Nanotubes
Authors: Ashim Pramanik, Martina Maria Calvino, Luisa Sciortino, Pooria Pasbakhsh, Giuseppe Cavallaro, Giuseppe Lazzara, Fabrizio Messina, Alice Sciortino
First page: 151
Abstract: This study explores the use of Halloysite NanoTubes (HNTs) as photocatalysts capable of decomposing organic dyes under exposure to visible or ultraviolet light. Through a systematic series of photocatalytic experiments, we unveil that the photodegradation of Rhodamine B, used as a model cationic dye, is significantly accelerated in the presence of HNTs. We observe that the extent of RhB photocatalytic degradation in 100 min in the presence of the HNTs is ~four times higher compared to that of bare RhB. Moreover, under optimized conditions, the as-extracted photodegradation rate of RhB (~0.0022 min−1) is comparable to that of the previously reported work on the photodegradation of RhB in the presence of tubular nanostructures. A parallel effect is observed for anionic Coumarin photodegradation, albeit less efficiently. Our analysis attributes this discrepancy to the distinct charge states of the two dyes, influencing their attachment sites on HNTs. Cationic Rhodamine B molecules preferentially attach to the outer surface of HNTs, while anionic Coumarin molecules tend to attach to the inner surface. By leveraging the unique properties of HNTs, a family of naturally occurring nanotube structures, this research offers valuable insights for optimizing photocatalytic systems in the pursuit of effective and eco-friendly solutions for environmental remediation.
Citation: Photochem
PubDate: 2024-03-28
DOI: 10.3390/photochem4020009
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 163-178: Excited-State Dynamics of Carbazole and
tert-Butyl-Carbazole in Organic Solvents
Authors: Konstantin Moritz Knötig, Domenic Gust, Thomas Lenzer, Kawon Oum
First page: 163
Abstract: Carbazole-based molecular units are ubiquitous in organic optoelectronic materials; however, the excited-state relaxation of these compounds is still underexplored. Here, we provide a detailed investigation of carbazole (Cz) and 3,6-di-tert-butylcarbazole (t-Bu-Cz) in organic solvents using femtosecond and nanosecond UV–Vis–NIR transient absorption spectroscopy, as well as time-resolved fluorescence experiments upon photoexcitation in the deep-UV range. The initially prepared Sx singlet state has a (sub-)picosecond lifetime and decays to the S1 state by internal conversion (IC). The S1 state exhibits absorption peaks at 350, 600 and 1100 nm and has a lifetime of 13–15 ns, which is weakly dependent on the solvent. Energy transfer from vibrationally hot S1 molecules (S1*) to the surrounding solvent molecules takes place with a time constant of 8–20 ps. The T1 triplet state is populated by intersystem crossing (ISC) from S1 with a typical quantum yield of 51–56% and shows a lifetime which is typically in the few microseconds regime. The S1 and T1 states of both carbazole compounds in solution are strongly quenched by O2. Two-photon excitation leads to the formation of a small amount of the respective radical cation. The influence of the tert-butyl substituents on the photophysics is relatively weak and mainly reflects itself in a small increase in the Stokes shift. The results provide important photophysical information for the interpretation of carbazole relaxation in more complex environments.
Citation: Photochem
PubDate: 2024-03-30
DOI: 10.3390/photochem4020010
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 179-197: Excited-State Dynamics of Carbazole and
tert-Butyl-Carbazole in Thin Films
Authors: Konstantin Moritz Knötig, Domenic Gust, Kawon Oum, Thomas Lenzer
First page: 179
Abstract: Thin films of carbazole (Cz) derivatives are frequently used in organic electronics, such as organic light-emitting diodes (OLEDs). Because of the proximity of the Cz units, the excited-state relaxation in such films is complicated, as intermolecular pathways, such as singlet–singlet annihilation (SSA), kinetically compete with the emission. Here, we provide an investigation of two benchmark systems employing neat carbazole and 3,6-di-tert-butylcarbazole (t-Bu-Cz) films and also their thin film blends with poly(methyl methacrylate) (PMMA). These are investigated by a combination of atomic force microscopy (AFM), femtosecond and nanosecond transient absorption spectroscopy (fs-TA and ns-TA) and time-resolved fluorescence. Excitonic J-aggregate-type features are observed in the steady-state absorption and emission spectra of the neat films. The S1 state shows a broad excited-state absorption (ESA) spanning the entire UV–Vis–NIR range. At high S1 exciton number densities of about 4 × 1018 cm−3, bimolecular diffusive S1–S1 annihilation is found to be the dominant SSA process in the neat films with a rate constant in the range of 1–2 × 10−8 cm3 s−1. SSA produces highly vibrationally excited molecules in the electronic ground state (S0*), which cool down slowly by heat transfer to the quartz substrate. The results provide relevant photophysical insight for a better microscopic understanding of carbazole relaxation in thin-film environments.
Citation: Photochem
PubDate: 2024-04-09
DOI: 10.3390/photochem4020011
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 198-218: A Review of Visible Light Responsive
Photocatalysts for Arsenic Remediation in Water
Authors: Isabella Natali Sora, Francesca Fontana, Renato Pelosato, Benedetta Bertolotti
First page: 198
Abstract: This review summarizes the progress over the last fifteen years in visible light reactive photocatalysts for environmental arsenic remediation. The design and performance of several materials including (1) doped and surface functionalized TiO2, (2) binary composites combining TiO2 with another semiconductor that absorbs visible light radiation or a metal (Pt), (3) ternary composites incorporating TiO2, a conductive polymer that can retard electron-hole recombination and an excellent adsorbent material for the removal of As(V), (4) tungsten, zinc, and bismuth oxides, (5) g-C3N4 based catalysts, and (6) M@AgCl core–shell structures. These results show that long reaction time remains a major challenge in achieving high As(III) oxidation.
Citation: Photochem
PubDate: 2024-04-17
DOI: 10.3390/photochem4020012
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 219-221: The Role of Photophysics in
Photochemistry
Authors: Dirk Poelman
First page: 219
Abstract: Photochemistry is a broad subject [...]
Citation: Photochem
PubDate: 2024-04-29
DOI: 10.3390/photochem4020013
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 222-232: Titanium Nanostructures: Advancing
Photocatalysis in Complex Systems
Authors: Alondra A. Lugo-Ruiz, Sonia J. Bailón-Ruiz
First page: 222
Abstract: The use of semiconductor materials, specifically TiO2, for photocatalysis of organic pollutants has gained global interest as an effective method for contaminant removal from wastewater. Titanium dioxide (TiO2) is a widely studied photocatalyst and is considered one of the best for wastewater treatments due to its high stability, affordability, and nontoxicity. The discharge of wastewater from the textile industries, which constitutes around 20% of total textile effluent, has become a significant environmental concern, posing a threat to both the aquatic ecosystem and human health. We aimed to investigate the photodegradation of organic dyes like Amaranth (AM), Methyl Orange (MO), and Quinoline Yellow (QY), individually and in combination, in an aqueous suspension with varying concentrations of TiO2. Results indicate a significant degradation of all three dyes in the multicomponent, with approximately 40% degradation in the presence of the 0.050 g/L TiO2 after 360 min. These findings suggest that TiO2 has a significant potential as a nanocatalyst in complex matrices.
Citation: Photochem
PubDate: 2024-05-06
DOI: 10.3390/photochem4020014
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 233-270: Excitation Wavelength-Dependent
Photochemistry
Authors: Mounir Maafi
First page: 233
Abstract: The dependence of photochemistry on excitation wavelength is not a recently observed phenomenon; nonetheless, it has, surprisingly enough, been largely ignored in the field. The reasons for this situation are not fully understood but might be related to a provisional extension of Kasha’s rule to photochemistry, or perhaps to a difficulty to justify the kind of short time-scales implied in such photochemistry, that challenges the usually held view giving predominance to fast internal conversion and vibrational relaxation. Regardless of the reasons, it is still a matter of fact that a complete and satisfactory interpretation for experimentally proven wavelength-dependent photochemistry is not yet available and the community endeavor to build a holistic understanding and a comprehensive view of the phenomenon. The present review is a non-exhaustive overview of the published data in the field, reporting on some of the most prominent features, issues, and interpretations.
Citation: Photochem
PubDate: 2024-06-07
DOI: 10.3390/photochem4020015
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 271-284: Advances in Functional Ceramics for
Water Splitting: A Comprehensive Review
Authors: Julia Exeler, Thomas Jüstel
First page: 271
Abstract: The global demand for sustainable energy sources has led to extensive research regarding (green) hydrogen production technologies, with water splitting emerging as a promising avenue. In the near future the calculated hydrogen demand is expected to be 2.3 Gt per year. For green hydrogen production, 1.5 ppm of Earth’s freshwater, or 30 ppb of saltwater, is required each year, which is less than that currently consumed by fossil fuel-based energy. Functional ceramics, known for their stability and tunable properties, have garnered attention in the field of water splitting. This review provides an in-depth analysis of recent advancements in functional ceramics for water splitting, addressing key mechanisms, challenges, and prospects. Theoretical aspects, including electronic structure and crystallography, are explored to understand the catalytic behavior of these materials. Hematite photoanodes, vital for solar-driven water splitting, are discussed alongside strategies to enhance their performance, such as heterojunction structures and cocatalyst integration. Compositionally complex perovskite oxides and high-entropy alloys/ceramics are investigated for their potential for use in solar thermochemical water splitting, highlighting innovative approaches and challenges. Further exploration encompasses inorganic materials like metal oxides, molybdates, and rare earth compounds, revealing their catalytic activity and potential for water-splitting applications. Despite progress, challenges persist, indicating the need for continued research in the fields of material design and synthesis to advance sustainable hydrogen production.
Citation: Photochem
PubDate: 2024-06-12
DOI: 10.3390/photochem4020016
Issue No: Vol. 4, No. 2 (2024)
- Photochem, Vol. 4, Pages 1-13: Twisted 8-Acyl-1-dialkyl-amino-naphthalenes
Emit from a Planar Intramolecular Charge Transfer Excited State
Authors: Christopher Abelt, Kirsten Sweigart
First page: 1
Abstract: Fluorescence from dialkylamino donor–acyl acceptor substituted 1,8-naphthalene derivatives can occur either from a planar (PICT) or a twisted (TICT) intramolecular charge transfer excited state. The photophysical properties of 8-acetyl-1-(dimethyl-amino)naphthalene (3) and 8-pivaloyl-1-(dimethyl-amino)naphthalene (4) are compared with 1-methyl-2,3-dihydronaphtho[1,8-bc]azepin-4(1H)-one (5). In 3 and 4, both the carbonyl and amino groups are forced to twist out of the plane of the naphthalene ring. In 5, these groups are nearly coplanar with the naphthalene. Neither 3 nor 4 fluoresce as strongly as 5, but all three show similar degrees of solvato-chromism and all are strongly quenched by alcohol solvents. Nitrile 6, 8-cyano-1-(dimethyl-amino)naphthalene, does not show the same degree of solvato-chromism as 3–5, nor is it as affected by alcohols. Calculations corroborate the experimental results, indicating that 3–5 emit from a PICT excited state.
Citation: Photochem
PubDate: 2024-01-04
DOI: 10.3390/photochem4010001
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 14-23: Survey of T1 and T2 Energies of
Intramolecular Singlet Fission Chromophores
Authors: Guoying Yao, Zhenyu Yang, Tao Zeng
First page: 14
Abstract: Singlet fission is a desired process in photovoltaics since it enhances photoelectric conversion efficiency. Intramolecular singlet fission is of special interest as the fission efficiency can be improved through tuning configurations between chromophore units that are covalently connected. However, intramolecular singlet fission chromophores feature a large tetraradical character, and may tend to dissatisfy the ET2>2ET1 criterion for all singlet fission chromophores, intramolecular or not. We performed spin-flip time-dependent density functional theory calculations for a collection of representative intramolecular singlet fission chromophores to show that this is indeed the case.
Citation: Photochem
PubDate: 2024-01-10
DOI: 10.3390/photochem4010002
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 24-39: Interactions of CdSe Nanocrystals with
Cationic Proteins Extracted from Moringa oleifera Seeds
Authors: Likius Shipwiisho Daniel, Salatiel Kapofi, Martha Kandawa-Schulz, Habauka Majority Kwaambwa
First page: 24
Abstract: Even with significant developments in nanoscience, relatively little is known about the interactions of nanocrystal semiconducting materials with bio-macromolecules. To investigate the interfacial phenomena of cadmium selenide quantum dot (CdSe QD) nanocrystals with proteins extracted from Moringa oleifera seeds, different concentrations of cadmium selenide quantum dots–Moringa oleifera seed protein (CdSe–MSP) complexes were prepared. Respective CdSe QDs with hexagonal phase and crystalline size in the range of 4–7 nm were synthesized and labelled with the purified mesoporous MSP having a surface area of 8.4 m2/g. The interaction mechanism between CdSe QDs and MSP was studied using UV–Vis absorption, fluorescence emission and Fourier Transform Infrared spectroscopies. The UV–Vis absorption spectra showed absorption bands of CdSe–MSP complexes at 546.5 nm. The fluorescence intensity of CdSe QDs was found to decrease with increasing concentration of MSP. The thermodynamic potentials ∆Hθ (−321.3 × 103 Jmol−1); ∆Sθ (156.0 JK−1mol−1) and ∆Gθ (−46.6 × 103 Jmol−1) were also calculated. The stability of the complex found is strongly influenced by electrostatics interaction and surface-bound complexation equilibrium attraction. This information can help to elucidate the surface characteristics of MSP and its potential interactions with other molecules or nanoparticles.
Citation: Photochem
PubDate: 2024-01-15
DOI: 10.3390/photochem4010003
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 40-56: The Rhodamine–Perylene Compact
Electron Donor–Acceptor Dyad: Spin-Orbit Charge-Transfer Intersystem
Crossing and the Energy Balance of the Triplet Excited States
Authors: Muhammad Imran, Dongyi Liu, Kaiyue Ye, Xue Zhang, Jianzhang Zhao
First page: 40
Abstract: We prepared a rhodamine (RB)–perylene (Pery) compact electron donor/acceptor dyad (RB–Pery) to study the spin-orbit charge-transfer intersystem crossing (SOCT–ISC). The UV–vis absorption spectrum indicates a negligible electronic interaction between the donor and acceptor at ground state. However, the fluorescence of both the RB and Pery units are quenched in the dyad, which is attributed to the photoinduced electron transfer, supported by the electrochemical studies. Nanosecond transient absorption (ns-TA) spectra show delocalized triplet states, i.e., there is an excited-state equilibrium between Pery and the RB triplet states. The triplet state lifetime was determined as 109.8 μs. With intermolecular triplet–triplet energy transfer, monitored using ns-TA spectra, the triplet-state energy balance between RB and Pery in RB–Pery was confirmed. The proposed cascade photophysical processes of the dyad are 1RB*-Pery→RB–Pery+•→[3RB*-Pery↔RB-3Pery*]. Moreover, long-lived rhodamine radical cation (in milliseconds) was detected in both deaerated/aerated non-polar or low-polarity solvents (i.e., p-xylene, toluene). The potential energy curve of the dyad against the variation in the dihedral angle between the two units indicates large torsional freedom (53°~128°) in RB–Pery, which leads to inefficient SOCT–ISC; consequently, low singlet-oxygen quantum yields (ΦΔ = 2~8%) were observed.
Citation: Photochem
PubDate: 2024-01-29
DOI: 10.3390/photochem4010004
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 57-110: Inverse Problems in Pump–Probe
Spectroscopy
Authors: Denis S. Tikhonov, Diksha Garg, Melanie Schnell
First page: 57
Abstract: Ultrafast pump–probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates’ lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte-Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution.
Citation: Photochem
PubDate: 2024-01-31
DOI: 10.3390/photochem4010005
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 111-127: Physicochemical Properties of Tungsten
Trioxide Photoanodes Fabricated by Wet Coating of Soluble, Particulate,
and Mixed Precursors
Authors: Valli Kamala Laxmi Ramya Chittoory, Marketa Filipsika, Radim Bartoš, Marcela Králová, Petr Dzik
First page: 111
Abstract: Advanced oxidation processes are emerging technologies for the decomposition of organic pollutants in various types of water by harnessing solar energy. The purpose of this study is to examine the physicochemical characteristics of tungsten(VI) oxide (WO3) photoanodes, with the aim of enhancing oxidation processes in the treatment of water. The fabrication of WO3 coatings on conductive fluorine-doped tin oxide (FTO) substrates was achieved through a wet coating process that utilized three different liquid formulations: a dispersion of finely milled WO3 particles, a fully soluble WO3 precursor (acetylated peroxo tungstic acid), and a combination of both (applying a brick-and-mortar strategy). Upon subjecting the WO3 coatings to firing at a temperature of 450 °C, it was observed that their properties exhibited marked variations. The fabricated photoanodes are examined using a range of analytical techniques, including profilometry, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and voltammetry. The experimental data suggest that the layers generated through the combination of particulate ink and soluble precursor (referred to as the brick-and-mortar building approach) display advantageous physicochemical properties, rendering them suitable for use as photoanodes in photoelectrochemical cells.
Citation: Photochem
PubDate: 2024-02-01
DOI: 10.3390/photochem4010006
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 128-137: Evaluation of MAA Analogues as Potential
Candidates to Increase Photostability in Sunscreen Formulations
Authors: Jacobo Soilán, Leonardo López-Cóndor, Beatriz Peñín, José Aguilera, María Victoria de Gálvez, Diego Sampedro, Raúl Losantos
First page: 128
Abstract: Avobenzone is one of the most widely used sunscreens in skin care formulations, but suffers from some drawbacks, including photo instability. To mitigate this critical issue, the use of octocrylene as a stabilizer is a common approach in these products. However, octocrylene has been recently demonstrated to show potential phototoxicity. The aim of this work is to analyze the performance of a series of mycosporine-like amino acid (MAA)-inspired compounds to act as avobenzone stabilizers as an alternative to octocrylene. Different avobenzone/MAA analogue combinations included in galenic formulations were followed under increasing doses of solar-simulated UV radiation. Some of the synthetic MAA analogues analyzed were able to increase by up to two times the UV dose required for 50% of avobenzone photobleaching. We propose some of these MAA analogues as new candidates to act as avobenzone-stabilizing compounds in addition to their UV absorbance and antioxidant properties, together with a facile synthesis.
Citation: Photochem
PubDate: 2024-02-06
DOI: 10.3390/photochem4010007
Issue No: Vol. 4, No. 1 (2024)
- Photochem, Vol. 4, Pages 138-150: Torsional Disorder in Tetraphenyl
[3]-Cumulenes: Insight into Excited State Quenching
Authors: David Bain, Julia Chang, Yihuan Lai, Thomas Khazanov, Phillip J. Milner, Andrew J. Musser
First page: 138
Abstract: Cumulenes are linear molecules consisting of consecutive double bonds linking chains of sp-hybridized carbon atoms. They have primarily been of interest for potential use as molecular wires or in other nanoscale electronic devices, but more recently, other applications such as catalysis or even light harvesting through singlet fission have been speculated. Despite the recent theoretical and experimental interest, the photoexcitation of cumulenes typically results in quenching on the picosecond timescale, and the exact quenching mechanism for even the simplest of [3]-cumulenes lacks a clear explanation. In this report, we perform transient absorption spectroscopy on a set of model [3]-cumulene derivatives in a wide range of environmental conditions to demonstrate that the planarization of phenyl groups ultimately quenches the excited state. By restricting this intramolecular motion, we increase the excited state lifetime by a few nanoseconds, strongly enhancing photoluminescence and demonstrating an approach to stabilize them for photochemical applications.
Citation: Photochem
PubDate: 2024-02-09
DOI: 10.3390/photochem4010008
Issue No: Vol. 4, No. 1 (2024)
