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Keywords = ultraviolet-visible light

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17 pages, 1647 KiB  
Article
Application of Iron Oxides in the Photocatalytic Degradation of Real Effluent from Aluminum Anodizing Industries
by Lara K. Ribeiro, Matheus G. Guardiano, Lucia H. Mascaro, Monica Calatayud and Amanda F. Gouveia
Appl. Sci. 2025, 15(15), 8594; https://doi.org/10.3390/app15158594 (registering DOI) - 2 Aug 2025
Abstract
This study reports the synthesis and evaluation of iron molybdate (Fe2(MoO4)3) and iron tungstate (FeWO4) as photocatalysts for the degradation of a real industrial effluent from aluminum anodizing processes under visible light irradiation. The oxides [...] Read more.
This study reports the synthesis and evaluation of iron molybdate (Fe2(MoO4)3) and iron tungstate (FeWO4) as photocatalysts for the degradation of a real industrial effluent from aluminum anodizing processes under visible light irradiation. The oxides were synthesized via a co-precipitation method in an aqueous medium, followed by microwave-assisted hydrothermal treatment. Structural and morphological characterizations were performed using X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, ultraviolet–visible (UV–vis), and photoluminescence (PL) spectroscopies. The effluent was characterized by means of ionic chromatography, total organic carbon (TOC) analysis, physicochemical parameters (pH and conductivity), and UV–vis spectroscopy. Both materials exhibited well-crystallized structures with distinct morphologies: Fe2(MoO4)3 presented well-defined exposed (001) and (110) surfaces, while FeWO4 showed a highly porous, fluffy texture with irregularly shaped particles. In addition to morphology, both materials exhibited narrow bandgaps—2.11 eV for Fe2(MoO4)3 and 2.03 eV for FeWO4. PL analysis revealed deep defects in Fe2(MoO4)3 and shallow defects in FeWO4, which can influence the generation and lifetime of reactive oxygen species. These combined structural, electronic, and morphological features significantly affected their photocatalytic performance. TOC measurements revealed degradation efficiencies of 32.2% for Fe2(MoO4)3 and 45.3% for FeWO4 after 120 min of irradiation. The results highlight the critical role of morphology, optical properties, and defect structures in governing photocatalytic activity and reinforce the potential of these simple iron-based oxides for real wastewater treatment applications. Full article
(This article belongs to the Special Issue Application of Nanomaterials in the Field of Photocatalysis)
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33 pages, 4142 KiB  
Review
Advances in Wettability-Engineered Open Planar-Surface Droplet Manipulation
by Ge Chen, Jin Yan, Junjie Liang, Jiajia Zheng, Jinpeng Wang, Hongchen Pang, Xianzhang Wang, Zihao Weng and Wei Wang
Micromachines 2025, 16(8), 893; https://doi.org/10.3390/mi16080893 (registering DOI) - 31 Jul 2025
Viewed by 186
Abstract
Firstly, this paper reviews the fundamental theories of solid surface wettability and contact angle hysteresis. Subsequently, it further introduces four typical wettability-engineered surfaces with low hysteresis (superhydrophobic, superamphiphobic, super-slippery, and liquid-like smooth surfaces). Finally, it focuses on the latest research progress in the [...] Read more.
Firstly, this paper reviews the fundamental theories of solid surface wettability and contact angle hysteresis. Subsequently, it further introduces four typical wettability-engineered surfaces with low hysteresis (superhydrophobic, superamphiphobic, super-slippery, and liquid-like smooth surfaces). Finally, it focuses on the latest research progress in the field of droplet manipulation on open planar surfaces with engineered wettability. To achieve droplet manipulation, the core driving forces primarily stem from natural forces guided by bioinspired gradient surfaces or the regulatory effects of external fields. In terms of bioinspired self-propelled droplet movement, this paper summarizes research inspired by natural organisms such as desert beetles, cacti, self-aligning floating seeds of emergent plants, or water-walking insects, which construct bioinspired special gradient surfaces to induce Laplace pressure differences or wettability gradients on both sides of droplets for droplet manipulation. Moreover, this paper further analyzes the mechanisms, advantages, and limitations of these self-propelled approaches, while summarizing the corresponding driving force sources and their theoretical formulas. For droplet manipulation under external fields, this paper elaborates on various external stimuli including electric fields, thermal fields, optical fields, acoustic fields, and magnetic fields. Among them, electric fields involve actuation mechanisms such as directly applied electrostatic forces and indirectly applied electrocapillary forces; thermal fields influence droplet motion through thermoresponsive wettability gradients and thermocapillary effects; optical fields cover multiple wavelengths including near-infrared, ultraviolet, and visible light; acoustic fields utilize horizontal and vertical acoustic radiation pressure or acoustic wave-induced acoustic streaming for droplet manipulation; the magnetic force acting on droplets may originate from their interior, surface, or external substrates. Based on these different transport principles, this paper comparatively analyzes the unique characteristics of droplet manipulation under the five external fields. Finally, this paper summarizes the current challenges and issues in the research of droplet manipulation on the open planar surfaces and provides an outlook on future development directions in this field. Full article
(This article belongs to the Special Issue Advanced Microfluidic Chips: Optical Sensing and Detection)
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17 pages, 3206 KiB  
Article
Inverse Punicines: Isomers of Punicine and Their Application in LiAlO2, Melilite and CaSiO3 Separation
by Maximilian H. Fischer, Ali Zgheib, Iliass El Hraoui, Alena Schnickmann, Thomas Schirmer, Gunnar Jeschke and Andreas Schmidt
Separations 2025, 12(8), 202; https://doi.org/10.3390/separations12080202 - 30 Jul 2025
Viewed by 86
Abstract
The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. [...] Read more.
The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. These amphoteric molecules were synthesized via a straightforward four-step route and structurally tuned for hydrophobization by alkylation. Their performance as collectors was evaluated in microflotation experiments of lithium aluminate (LiAlO2) and silicate matrix minerals such as melilite and calcium silicate. Characterization techniques including ultraviolet-visible (UV-Vis), nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy as well as contact angle, zeta potential (ζ potential) and microflotation experiments revealed strong pH- and structure-dependent interactions with mineral surfaces. Notably, N-alkylated inverse Punicine derivatives showed high flotation yields for LiAlO2 at pH of 11, with a derivative possessing a dodecyl group attached to the nitrogen as collector achieving up to 86% recovery (collector conc. 0.06 mmol/L). Preliminary separation tests showed Li upgrading from 5.27% to 6.95%. Radical formation and light-response behavior were confirmed by ESR and flotation tests under different illumination conditions. These results demonstrate the potential of inverse Punicines as tunable, sustainable flotation reagents for advanced lithium recycling from complex slag systems. Full article
(This article belongs to the Special Issue Application of Green Flotation Technology in Mineral Processing)
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16 pages, 4296 KiB  
Article
Enhanced Photocathodic Protection Performance of TiO2/NiCo2S4 Composites for 304 Stainless Steel
by Honggang Liu, Hong Li, Xuan Zhang, Baizhao Xing, Zhuangzhuang Sun and Yanhui Li
Coatings 2025, 15(8), 874; https://doi.org/10.3390/coatings15080874 - 25 Jul 2025
Viewed by 283
Abstract
To address the corrosion of 304 stainless steel in marine environments, TiO2/NiCo2S4 composite photoanodes were fabricated via anodic oxidation and hydrothermal methods. X-ray diffraction, scanning electron microscope, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy analyses indicated the growth [...] Read more.
To address the corrosion of 304 stainless steel in marine environments, TiO2/NiCo2S4 composite photoanodes were fabricated via anodic oxidation and hydrothermal methods. X-ray diffraction, scanning electron microscope, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy analyses indicated the growth of hexagonal NiCo2S4 particles on anatase TiO2 nanotube arrays, forming a type-II heterojunction. Spectroscopy of ultraviolet-visible diffuse reflectance absorption showed that NiCo2S4 extended TiO2’s light absorption into the visible region. Electrochemical tests revealed that under visible light, the composite photoanode decreased the corrosion potential of 304ss to −0.7 V vs. SCE and reduced charge transfer resistance by 20% compared to pure TiO2. The enhanced performance stemmed from efficient electron-hole separation and transport enabled by the type-II heterojunction. Cyclic voltammetry tests indicated the composite’s electrochemical active surface area increased 1.8-fold, demonstrating superior catalytic activity. In conclusion, the TiO2/NiCo2S4 composite photoanode offers an effective approach for marine corrosion protection of 304ss. Full article
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31 pages, 4667 KiB  
Article
Harnessing Plant-Based Nanoparticles for Targeted Therapy: A Green Approach to Cancer and Bacterial Infections
by Mirela Claudia Rîmbu, Daniel Cord, Mihaela Savin, Alexandru Grigoroiu, Mirela Antonela Mihăilă, Mona Luciana Gălățanu, Viorel Ordeanu, Mariana Panțuroiu, Vasilica Țucureanu, Iuliana Mihalache, Oana Brîncoveanu, Adina Boldeiu, Veronica Anăstăsoaie, Carmen Elisabeta Manea, Roxana-Colette Sandulovici, Marinela Chirilă, Adina Turcu-Știolică, Emilia Amzoiu, Victor-Eduard Peteu, Cristiana Tănase, Bogdan Firtat and Carmen-Marinela Mihăilescuadd Show full author list remove Hide full author list
Int. J. Mol. Sci. 2025, 26(14), 7022; https://doi.org/10.3390/ijms26147022 - 21 Jul 2025
Viewed by 455
Abstract
This study investigates the antioxidant, antimicrobial, and antitumor activities of Taraxacum officinale (Dandelion) and Artemisia annua (Sweet Wormwood) extracts, along with their role in the green synthesis of gold (AuNPs) and silver nanoparticles (AgNPs). Bioreduction was achieved using aqueous and ethanolic extracts (100 [...] Read more.
This study investigates the antioxidant, antimicrobial, and antitumor activities of Taraxacum officinale (Dandelion) and Artemisia annua (Sweet Wormwood) extracts, along with their role in the green synthesis of gold (AuNPs) and silver nanoparticles (AgNPs). Bioreduction was achieved using aqueous and ethanolic extracts (100 mg/mL), enabling solvent-dependent comparisons. Nanoparticles were characterized using ultraviolet–visible spectroscopy (UV–Vis), fluorescence spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and zeta potential analysis. Each technique revealed complementary aspects of nanoparticle morphology, size, and stability, with UV–Vis indicating aggregation states and DLS confirming solvent-related size variation even at 3–5% ethanol. Gold nanoparticles synthesized from Dandelion showed strong antibacterial activity against Staphylococcus aureus, while silver nanoparticles from both plants were effective against Escherichia coli. Cytotoxicity assays indicated that silver nanoparticles obtained from ethanolic Dandelion extract containing 3% ethanol in aqueous solution (AgNPsEETOH3%-D) significantly reduced LoVo (p = 4.58 × 10−3) and MDA-MB-231 (p = 7.20 × 10−5) cell viability, with high selectivity indices (SI), suggesting low toxicity toward normal cells. Gold nanoparticles synthesized from aqueous Dandelion extract (AuNPsEaq-D) also showed favorable SI values (2.16 for LoVo and 8.41 for MDA-MB-231). Although some formulations demonstrated lower selectivity (SI < 1.5), the findings support the therapeutic potential of these biogenic nanoparticles. Further in vivo studies and pharmacokinetic evaluations are required to validate their clinical applicability. Full article
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18 pages, 5775 KiB  
Article
Precision Solar Spectrum Filtering in Aerogel Windows via Synergistic ITO-Ag Nanoparticle Doping for Hot-Climate Energy Efficiency
by Huilin Yang, Maoquan Huang, Mingyang Yang, Xuankai Zhang and Mu Du
Gels 2025, 11(7), 553; https://doi.org/10.3390/gels11070553 - 18 Jul 2025
Viewed by 183
Abstract
Windows are a major contributor to energy loss in buildings, particularly in hot climates where solar radiation heat gain significantly increases cooling demand. An ideal energy-efficient window must maintain high visible light transmittance while effectively blocking ultraviolet and near-infrared radiation, presenting a significant [...] Read more.
Windows are a major contributor to energy loss in buildings, particularly in hot climates where solar radiation heat gain significantly increases cooling demand. An ideal energy-efficient window must maintain high visible light transmittance while effectively blocking ultraviolet and near-infrared radiation, presenting a significant challenge for material design. We propose a plasma silica aerogel window utilizing the local surface plasmon resonance effect of plasmonic nanoparticles. This design incorporates indium tin oxide (ITO) nanospheres (for broad-band UV/NIR blocking) and silver (Ag) nanocylinders (targeted blocking of the 0.78–0.9 μm NIR band) co-doped into the silica aerogel. This design achieves a visible light transmittance of 0.8, a haze value below 0.12, and a photothermal ratio of 0.91. Building simulations indicate that compared to traditional glass, this window can achieve annual energy savings of 20–40% and significantly reduce the economic losses associated with traditional glass, providing a feasible solution for sustainable buildings. Full article
(This article belongs to the Section Gel Applications)
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21 pages, 7602 KiB  
Article
Visible-Light-Responsive Ag(Au)/MoS2-TiO2 Inverse Opals: Synergistic Plasmonic, Photonic, and Charge Transfer Effects for Photoelectrocatalytic Water Remediation
by Stelios Loukopoulos, Elias Sakellis, Polychronis Tsipas, Spiros Gardelis, Vassilis Psycharis, Marios G. Kostakis, Nikolaos S. Thomaidis and Vlassis Likodimos
Nanomaterials 2025, 15(14), 1076; https://doi.org/10.3390/nano15141076 - 11 Jul 2025
Viewed by 400
Abstract
Titanium dioxide (TiO2) is a benchmark photocatalyst for environmental applications, but its limited visible-light activity due to a wide band gap and fast charge recombination restricts its practical efficiency. This study presents the development of heterostructured Ag (Au)/MoS2-TiO2 [...] Read more.
Titanium dioxide (TiO2) is a benchmark photocatalyst for environmental applications, but its limited visible-light activity due to a wide band gap and fast charge recombination restricts its practical efficiency. This study presents the development of heterostructured Ag (Au)/MoS2-TiO2 inverse opal (IO) films that synergistically integrate photonic, plasmonic, and semiconducting functionalities to overcome these limitations. The materials were synthesized via a one-step evaporation-induced co-assembly approach, embedding MoS2 nanosheets and plasmonic nanoparticles (Ag or Au) within a nanocrystalline TiO2 photonic framework. The inverse opal architecture enhances light harvesting through slow-photon effects, while MoS2 and plasmonic nanoparticles improve visible-light absorption and charge separation. By tuning the template sphere size, the photonic band gap was aligned with the TiO2-MoS2 absorption edge and the localized surface plasmon resonance of Ag, enabling optimal spectral overlap. The corresponding Ag/MoS2-TiO2 photonic films exhibited superior photocatalytic and photoelectrocatalytic degradation of tetracycline under visible light. Ultraviolet photoelectron spectroscopy and Mott–Schottky analysis confirmed favorable band alignment and Fermi level shifts that facilitate interfacial charge transfer. These results highlight the potential of integrated photonic–plasmonic-semiconductor architectures for efficient solar-driven water treatment. Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
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27 pages, 7247 KiB  
Article
Layered Perovskite La2Ti2O7 Obtained by Sol–Gel Method with Photocatalytic Activity
by Alexandra Ilie, Luminița Predoană, Crina Anastasescu, Silviu Preda, Ioana Silvia Hosu, Ruxandra M. Costescu, Daniela C. Culiță, Veronica Brătan, Ioan Balint and Maria Zaharescu
Appl. Sci. 2025, 15(14), 7665; https://doi.org/10.3390/app15147665 - 8 Jul 2025
Viewed by 295
Abstract
This paper presents the synthesis of La2Ti2O7 nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation [...] Read more.
This paper presents the synthesis of La2Ti2O7 nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH4. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH3CH2OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH3CH2OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article
(This article belongs to the Special Issue Application of Nanomaterials in the Field of Photocatalysis)
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12 pages, 7037 KiB  
Article
Microwave-Assisted Reduction Technology for Recycling of Hematite Nanoparticles from Ferrous Sulfate Residue
by Genkuan Ren
Materials 2025, 18(14), 3214; https://doi.org/10.3390/ma18143214 - 8 Jul 2025
Viewed by 275
Abstract
Accumulation of ferrous sulfate residue (FSR) not only occupies land but also results in environmental pollution and waste of iron resource; thus, recycling of iron from FSR has attracted widespread concern. To this end, this article shows fabrication and system analysis of hematite [...] Read more.
Accumulation of ferrous sulfate residue (FSR) not only occupies land but also results in environmental pollution and waste of iron resource; thus, recycling of iron from FSR has attracted widespread concern. To this end, this article shows fabrication and system analysis of hematite (HM) nanoparticles from FSR via microwave-assisted reduction technology. Physicochemical properties of HM nanoparticles were investigated by multiple analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV-Vis) spectrum, vibrating sample magnetometer (VSM), and the Brunauer–Emmett–Teller (BET) method. Analytic results indicated that the special surface area, pore volume, and pore size of HM nanoparticles with the average particle size of 45 nm were evaluated to be ca. 20.999 m2/g, 0.111 cm3/g, and 0.892 nm, respectively. Magnetization curve indicated that saturation magnetization Ms for as-synthesized HM nanoparticles was calculated to be approximately 1.71 emu/g and revealed weakly ferromagnetic features at room temperature. In addition, HM nanoparticles exhibited noticeable light absorption performance for potential applications in many fields such as electronics, optics, and catalysis. Hence, synthesis of HM nanoparticles via microwave-assisted reduction technology provides an effective way for utilizing FSR and easing environmental burden. Full article
(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)
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19 pages, 3941 KiB  
Article
Efficient Energy Transfer Down-Shifting Material for Dye-Sensitized Solar Cells
by Emeka Harrison Onah, N. L. Lethole and P. Mukumba
Materials 2025, 18(14), 3213; https://doi.org/10.3390/ma18143213 - 8 Jul 2025
Viewed by 262
Abstract
Dye-sensitized solar cells (DSSCs) are promising alternatives for power generation due to their environmental friendliness, cost effectiveness, and strong performance under diffused light. Conversely, their low spectral response in the ultraviolet (UV) region significantly obliterates their overall performance. The so-called luminescent down-shifting (LDS) [...] Read more.
Dye-sensitized solar cells (DSSCs) are promising alternatives for power generation due to their environmental friendliness, cost effectiveness, and strong performance under diffused light. Conversely, their low spectral response in the ultraviolet (UV) region significantly obliterates their overall performance. The so-called luminescent down-shifting (LDS) presents a practical solution by converting high-energy UV photons into visible light that can be efficiently absorbed by sensitizer dyes. Herein, a conventional solid-state technique was applied for the synthesis of an LDS, europium (II)-doped barium orthosilicate (BaSiO3:Eu2+) material. The material exhibited strong UV absorption, with prominent peaks near 400 nm and within the 200–300 nm range, despite a weaker response in the visible region. The estimated optical bandgap was 3.47 eV, making it well-suited for UV absorbers. Analysis of the energy transfer mechanism from the LDS material to the N719 dye sensitizer depicted a strong spectral overlap of 2×1010M1cm1nm4, suggesting efficient energy transfer from the donor to the acceptor. The estimated Förster distance was approximately 6.83 nm, which matches the absorption profile of the dye-sensitizer. Our findings demonstrate the potential of BaSiO3:Eu2+ as an effective LDS material for enhancing UV light absorption and improving DSSC performance through increased spectral utilization and reduced UV-induced degradation. Full article
(This article belongs to the Special Issue Advanced Luminescent Materials and Applications)
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14 pages, 2742 KiB  
Article
Non-Invasive Painting Pigment Classification Through Supervised Machine Learning
by Michal Piotr Markowski, Solongo Gansukh, Mateusz Madry, Robert Borowiec, Jaroslaw Rogoz and Boguslaw Szczupak
Appl. Sci. 2025, 15(13), 7594; https://doi.org/10.3390/app15137594 - 7 Jul 2025
Viewed by 244
Abstract
Accurate pigment classification is essential for the analysis and conservation of historical paintings. This study presents a non-invasive approach based on supervised machine learning for classifying pigments using image data acquired under three distinct spectral illumination conditions: visible-light reflectography (VIS), ultraviolet false-color imaging [...] Read more.
Accurate pigment classification is essential for the analysis and conservation of historical paintings. This study presents a non-invasive approach based on supervised machine learning for classifying pigments using image data acquired under three distinct spectral illumination conditions: visible-light reflectography (VIS), ultraviolet false-color imaging (UVFC), and infrared false-color imaging (IRFC). A dataset was constructed by extracting 32 × 32 pixel patches from pigment samples, resulting in 200 classes representing 40 unique pigments with five preparation variants each. A total of 600 initial raw images were acquired, from which 4000 image patches were extracted for feature engineering. Feature vectors were obtained from visible reflectography, ultraviolet false-color imaging (UVFC), and infrared false-color imaging (IRFC) using statistical descriptors derived from RGB channels. This study demonstrates that accurate pigment classification can be achieved with a minimal set of three illumination types, offering a practical and cost-effective alternative to hyperspectral imaging in real-world conservation practice. Among the evaluated classifiers, the random forest model achieved the highest accuracy (99.30 ±0.15%). The trained model was subsequently validated on annotated regions of historical paintings, demonstrating its robustness and applicability. The proposed framework offers a lightweight, interpretable, and scalable solution for non-invasive pigment analysis in cultural heritage research that can be implemented with accessible imaging hardware and minimal post-processing. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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20 pages, 6691 KiB  
Article
An Easy and Single-Step Biosynthesis of WO3 with High Photocatalytic Degradation Activity for Dye Degradation
by Azza A. Al-Ghamdi, Reema H. Aldahiri, Elham A. Alzahrani, Naha Meslet Alsebaii, Sumbul Hafeez, Shafiul Haque, Poonam Dwivedi and Seungdae Oh
Nanomaterials 2025, 15(13), 1036; https://doi.org/10.3390/nano15131036 - 3 Jul 2025
Viewed by 300
Abstract
In the present study, a photodegradation technique was employed for the removal of methylene blue dye from aqueous solution using a tungsten oxide-based photocatalyst. The photocatalyst was synthesized via a green synthesis route utilizing a plant extract (PE) under acidic conditions. The synthesized [...] Read more.
In the present study, a photodegradation technique was employed for the removal of methylene blue dye from aqueous solution using a tungsten oxide-based photocatalyst. The photocatalyst was synthesized via a green synthesis route utilizing a plant extract (PE) under acidic conditions. The synthesized photocatalyst was characterized by various spectroscopic and microscopic techniques that confirmed the presence of various functional groups on the catalyst surface and revealed a narrow bandgap of ~3.0 eV. The synthesized particles exhibited a nanoscale dimension ranging from 10 to 15 nm. The photocatalytic activity of the material was evaluated under ultraviolet light, visible light, and sunlight irradiation, demonstrating the efficient degradation of methylene blue under all light sources. Furthermore, catalysis reusability studies indicated excellent stability, with consistent photocatalytic performance observed after five successive cycles. Full article
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20 pages, 4257 KiB  
Article
Photocatalytic Degradation of Toxic Dyes on Cu and Al Co-Doped ZnO Nanostructured Films: A Comparative Study
by Nadezhda D. Yakushova, Ivan A. Gubich, Andrey A. Karmanov, Alexey S. Komolov, Aleksandra V. Koroleva, Ghenadii Korotcenkov and Igor A. Pronin
Technologies 2025, 13(7), 277; https://doi.org/10.3390/technologies13070277 - 1 Jul 2025
Viewed by 311
Abstract
The article suggests a simple one-step sol–gel method for synthesizing nanostructured zinc oxide films co-doped with copper and aluminum. It shows the possibility of forming hierarchical ZnO:Al:Cu nanostructures combining branches of different sizes and ranks and quasi-spherical fractal aggregates. It demonstrates the use [...] Read more.
The article suggests a simple one-step sol–gel method for synthesizing nanostructured zinc oxide films co-doped with copper and aluminum. It shows the possibility of forming hierarchical ZnO:Al:Cu nanostructures combining branches of different sizes and ranks and quasi-spherical fractal aggregates. It demonstrates the use of the synthesized samples as highly efficient photocatalysts providing the decomposition of toxic dyes (methyl orange) under the action of both ultraviolet radiation and visible light. It establishes the contribution of the average crystallite size, the proportion of zinc atoms in the crystalline phase, their nanostructure, as well as X-ray amorphous phases of copper and aluminum to the efficiency of the photocatalysis process. Full article
(This article belongs to the Section Environmental Technology)
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25 pages, 4696 KiB  
Article
Enhancing Photocatalytic Activity with the Substantial Optical Absorption of Bi2S3-SiO2-TiO2/TiO2 Nanotube Arrays for Azo Dye Wastewater Treatment
by Amal Abdulrahman, Zaina Algarni, Nejib Ghazouani, Saad Sh. Sammen, Abdelfattah Amari and Miklas Scholz
Water 2025, 17(13), 1875; https://doi.org/10.3390/w17131875 - 24 Jun 2025
Viewed by 695
Abstract
One-dimensional TiO2 nanotube arrays (TNAs) were vertically aligned and obtained via the electrochemical anodization method. In this study, Bi2S3-TiO2-SiO2/TNA heterojunction photocatalysts were successfully prepared with different amounts of Bismuth(III) sulfide (Bi2S3 [...] Read more.
One-dimensional TiO2 nanotube arrays (TNAs) were vertically aligned and obtained via the electrochemical anodization method. In this study, Bi2S3-TiO2-SiO2/TNA heterojunction photocatalysts were successfully prepared with different amounts of Bismuth(III) sulfide (Bi2S3) loading on the TNAs by the successive ionic layer adsorption and reaction (SILAR) method and characterized by X-ray diffraction (XRD) patterns, field-emission scanning electron microscope–energy-dispersive spectroscopy (FESEM-EDS), Fourier transform infrared (FTIR) spectra, ultraviolet-visible diffuse reflectance spectra (UV–Vis/DRS), and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic performances of the samples were investigated by degrading Basic Yellow 28 (BY 28) under visible-light irradiation. Optimization of the condition using the response surface methodology (RSM) and central composite rotatable design (CCRD) technique resulted in the degradation of BY 28 dye, showing that the catalyst with 9.6 mg/cm2 (designated as Bi2S3(9.6)-TiO2-SiO2/TNA) showed the maximum yield in the degradation process. The crystallite size of about 17.03 nm was estimated using the Williamson–Hall method. The band gap energies of TiO2-SiO2/TNA and Bi2S3(9.6)-TiO2-SiO2/TNA were determined at 3.27 and 1.87 eV for the direct electronic transitions, respectively. The EIS of the ternary system exhibited the smallest arc diameter, indicating an accelerated charge transfer rate that favors photocatalytic activity. Full article
(This article belongs to the Special Issue Global Water Resources Management)
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23 pages, 3592 KiB  
Article
Enhancing Optical Properties and Cost-Effectiveness of Sol–Gel TiO2 Nanomaterials Through Experimental Design
by Felipe Anchieta e Silva, Timóteo Adorno de Almeida, Argimiro R. Secchi, José Carlos Pinto and Thenner Silva Rodrigues
Processes 2025, 13(7), 1988; https://doi.org/10.3390/pr13071988 - 24 Jun 2025
Viewed by 484
Abstract
The sol–gel synthesis of titanium dioxide (TiO2) nanostructures is investigated in the present work in order to optimize synthesis parameters and enhance the optical properties and cost-effectiveness of the obtained materials. TiO2 is widely used in photocatalysis, photovoltaics, and environmental [...] Read more.
The sol–gel synthesis of titanium dioxide (TiO2) nanostructures is investigated in the present work in order to optimize synthesis parameters and enhance the optical properties and cost-effectiveness of the obtained materials. TiO2 is widely used in photocatalysis, photovoltaics, and environmental applications due to its high stability, tunable band gap, and strong light absorption. The sol–gel method offers a scalable, cost-effective route for producing nanostructured TiO2, although the precise control over particle morphology remains challenging. For this reason, in the present work, a statistical design of experiments (DOE) approach is employed to systematically refine reaction conditions through the manipulation of precursor concentrations, solvent ratios, and reaction volume. The experimental results obtained indicate that acetic acid is a key catalyst and stabilizing agent, significantly improving nucleation control and particle formation. Moreover, it is also shown that solvent dilution, particularly with acetic acid, leads to the formation of TiO2 nanorods with enhanced optical properties. Additionally, scanning electron micrographs revealed that controlled synthesis conditions can reduce the particle size distribution and improve structural uniformity. Moreover, X-ray diffraction analyses confirmed the formation of a pure anatase crystalline phase, while ultraviolet–visible spectroscopy analyses indicated the existence of an optimal band gap for photocatalytic applications. Finally, the cost analysis showed that acetic acid-assisted synthesis can reduce production costs and simultaneously maintain high optical properties. Therefore, the present study highlights that proper manipulation and control of reaction conditions during sol–gel syntheses can allow the manufacture of high-performance TiO2 nanomaterials for advanced technological applications, also providing a foundation for the development of cost-effective materials. Full article
(This article belongs to the Special Issue Metal Oxides and Their Composites for Photocatalytic Degradation)
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