Search Results (1,950)

In this study, a Z-scheme Ho₂InSbO₇/Ag₃PO₄ (HAO) heterojunction photocatalyst was successfully fabricated for the first time by ultrasound-assisted solvothermal method. The structural features, compositional components and morphological characteristics of the synthesized materials were thoroughly characterized by a series of techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. A comprehensive array of analytical techniques, including ultraviolet-visible diffuse reflectance absorption spectra, photoluminescence spectroscopy, time-resolved photoluminescence spectroscopy, photocurrent testing, electrochemical impedance spectroscopy, electron paramagnetic resonance, and ultraviolet photoelectron spectroscopy, was employed to systematically investigate the optical, chemical, and photoelectronic properties of the materials. Using oxytetracycline (OTC), a representative tetracycline antibiotic, as the target substrate, the photocatalytic activity of the HAO composite was assessed under visible light irradiation. Comparative analyses demonstrated that the photocatalytic degradation capability of the HAO composite surpassed those of its individual components. Notably, during the degradation process, the application of the HAO composite resulted in an impressive removal efficiency of 99.89% for OTC within a span of 95 min, along with a total organic carbon mineralization rate of 98.35%. This outstanding photocatalytic performance could be ascribed to the efficient Z-scheme electron-hole separation system occurring between Ho₂InSbO₇ and Ag₃PO₄. Moreover, the adaptability and stability of the HAO heterojunction were thoroughly validated. Through experiments involving the capture of reactive species and electron paramagnetic resonance analysis, the active species generated by HAO were identified as hydroxyl radicals (•OH), superoxide anions (•O₂⁻), and holes (h⁺). This identification provides valuable insights into the mechanisms and pathways associated with the photodegradation of OTC. In conclusion, this research not only elucidates the potential of HAO as an efficient Z-scheme heterojunction photocatalyst but also marks a significant contribution to the advancement of sustainable remediation strategies for OTC contamination. Full article

Persistent reactive azo dyes released from textile finishing are a serious threat to water systems, but effective methods using sunlight to break them down are still limited. Everzol Yellow 3RS (EY-3RS) is particularly recalcitrant: past studies have relied almost exclusively on physical adsorption onto natural or modified clays and zeolites, and no photocatalytic pathway employing engineered nanomaterials has been documented to date. This study reports the synthesis, characterization, and performance of a visible-active ternary nanocomposite, Cu₄O₃/ZrO₂/TiO₂, prepared hydrothermally alongside its binary (Cu₄O₃/ZrO₂) and rutile TiO₂ counterparts. XRD, FT-IR, SEM-EDX, UV-Vis, and PL analyses confirm a heterostructured architecture with a narrowed optical bandgap of 2.91 eV, efficient charge separation, and a mesoporous nanosphere-in-matrix morphology. Photocatalytic tests conducted under midsummer sunlight reveal that the ternary catalyst removes 91.41% of 40 ppm EY-3RS within 100 min, markedly surpassing the binary catalyst (86.65%) and TiO₂ (81.48%). Activity trends persist across a wide range of operational variables, including dye concentrations (20–100 ppm), catalyst dosages (10–40 mg), pH levels (3–11), and irradiation times (up to 100 min). The material retains ≈ 93% of its initial efficiency after four consecutive cycles, evidencing good reusability. This work introduces the first nanophotocatalytic strategy for EY-3RS degradation and underscores the promise of multi-oxide heterojunctions for solar-driven remediation of colored effluents. Full article

Background/Objectives: The rapid emergence of multidrug-resistant bacterial infections demands innovative non-antibiotic therapeutic strategies. Dual-modal photoresponse therapy integrating photodynamic (PDT) and photothermal (PTT) effects offers a promising rapid antibacterial approach, yet designing single-material systems with synergistic enhancement remains challenging. This study aims to develop uniform Cu-based metal–organic framework micrometer cubes (Cu-BN) for efficient PDT/PTT synergy. Methods: Cu-BN cubes were synthesized via a one-step hydrothermal method using Cu(NO₃)₂ and 2-amino-p-benzoic acid. The material’s dual-mode responsiveness to visible light (420 nm) and near-infrared light (808 nm) was characterized through UV–Vis spectroscopy, photothermal profiling, and reactive oxygen species (ROS) generation assays. Antibacterial efficacy against multidrug-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was quantified via colony counting under dual-light irradiation. Results: Under synergistic 420 + 808 nm irradiation for 15 min, Cu-BN (200 μg/mL) achieved rapid eradication of multidrug-resistant E. coli (99.94%) and S. aureus (99.83%). The material reached 58.6 °C under dual-light exposure, significantly exceeding single-light performance. Photodynamic analysis confirmed a 78.7% singlet oxygen (¹O₂) conversion rate. This enhancement stems from PTT-induced membrane permeabilization accelerating ROS diffusion, while PDT-generated ROS sensitized bacteria to thermal damage. Conclusions: This integrated design enables spatiotemporal PDT/PTT synergy within a single Cu-BN system, establishing a new paradigm for rapid-acting, broad-spectrum non-antibiotic antimicrobials. The work provides critical insights for developing light-responsive biomaterials against drug-resistant infections. Full article

Cobalt and Nickel (Co, Ni) co-doped magnesium oxide (MgO) nanoparticles (NPs) have been synthesized using the coprecipitation method. The structural, chemical, and optical properties of the as-synthesized NPs are systematically investigated using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV-visible spectroscopy. It is found that the optical bandgap of co-doped MgO NPs reduces from 2.30 to 1.98 eV (14%) with increasing Ni dopant concentrations up to 7%. The Co_0.05Ni_0.07Mg_0.88O NPs exhibit a high photocatalytic degradation efficiency of 93% for methylene blue dye (MB) under natural sunlight irradiation for 240 min. Our findings indicate that the Co_0.05Ni_xMg_0.95−xO NPs have strong potential for use as photocatalysts in industrial wastewater treatment. Full article

Commercially available bismuth subcarbonate (Bi₂O₂CO₃) was treated with nitric acid and the surfactant cetyltrimethylammonium bromide. The treated catalysts exhibited enhanced photocatalytic activity compared to pure Bi₂O₂CO₃ in the decolorization of rhodamine B (RhB) under visible light irradiation. The absorbance at 554 nm gradually decreased over time and disappeared completely within 80 min. The crystal structure, morphology, and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The improved photocatalytic activity of the treated catalysts was attributed to partial carbonate removal and the formation of Bi⁵⁺ species. Scavenger experiments indicated that superoxide radicals (·O₂⁻) and photogenerated holes (h⁺) played significant roles in the photocatalytic decolorization of RhB. Full article

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

Copper-doped indium zinc sulfides were synthesized by heating and stirring a mixture of zinc chloride, indium chloride tetrahydrate, thioacetamide, and copper chloride at 180 °C for 18 h. Among these, Zn_5.7Cu_0.3In₂S₉ exhibited a hydrogen-producing activity of 1660 μmol/g·h, which was approximately five times higher than that of pristine indium zinc sulfide. Therefore, the catalyst was characterized to investigate the effect of Cu addition. PL results revealed that the incorporation of Cu reduced the fluorescence intensity, indicating suppressed recombination of photogenerated electron–hole pairs. DRS showed that the Cu addition enhanced optical absorption in the visible-light region and narrowed the band gap. These findings suggest that the incorporation of copper into indium zinc sulfide improves its photocatalytic activity. Full article

Hexavalent chromium (Cr(VI)), a common contaminant in industrial wastewater, poses severe health risks due to its carcinogenic and mutagenic properties. Consequently, the development of efficient and environmentally friendly methods to reduce Cr(VI) to the less toxic trivalent chromium (Cr(III)) is of great importance. In this study, we present a cost-effective photocatalytic approach using graphitic carbon nitride (g-C₃N₄) modified with 1,3,5-trihydroxybenzene via one-step thermal condensation. The modified photo-catalyst exhibited improved surface area, porosity, visible-light absorption, and a narrowed band gap, all of which contributed to enhanced charge separation. As a result, nearly complete reduction in Cr(VI) was achieved within 90 min under visible-light irradiation. Further optimization of catalyst dosage and EDTA concentration gave even higher reduction efficiency. This work offers a promising strategy for the design of high-performance photocatalysts for environmental remediation. Full article

The rapid increase in polystyrene (PS) production has led to substantial growth in plastic waste, posing serious environmental and waste management challenges. Current disposal techniques are unsustainable, relying heavily on harsh conditions, high energy input, and generating environmentally harmful byproducts. This review critically discusses alternative green approaches for PS treatment through photocatalytic and non-photocatalytic upcycling methods. Photocatalytic methods utilize light energy (UV, visible, or broad-spectrum irradiation) to initiate radical reactions that cleave the inert carbon backbone of PS. In contrast, non-photocatalytic strategies achieve backbone degradation without direct light activation, often employing catalysts and thermal energy. Both approaches effectively transform PS waste into higher-value compounds, such as benzoic acid and acetophenone, though yields remain moderate for most reported methods. Current limitations, including catalyst performance, low yields, and impurities in real-world PS waste, are highlighted. Future directions toward enhancing the efficiency, selectivity, and scalability of PS upcycling processes are proposed to address the growing plastic waste crisis sustainably. Full article

Titanium dioxide (TiO₂), a widely used semiconductor in photocatalysis owing to its adequate potential for water hydrolysis, chemical stability, low toxicity, and low cost. However, its efficiency is limited by fast charge-carrier recombination and poor visible light absorption. Coupling TiO₂ with a p-type semiconductor, such as nickel oxide (NiO), forming a p-n heterojunction, decreases the recombination of charge carriers and increases photocatalytic activity. In this work, the surface of TiO₂ modified with NiO nanoparticles (NPs) induced by radiolysis for photocatalytic hydrogen production was studied. The photocatalytic activity of NiO/TiO₂ was evaluated using methanol as a hole scavenger under UV–visible light. All modified samples presented superior photocatalytic activity compared to bare TiO₂. The dynamics of the charge carriers, a key electronic phenomenon in photocatalysis, was investigated by time-resolved microwave conductivity (TRMC). The results highlight the crucial role of Ni-based NPs modification in enhancing the separation of the charge carrier and activity under UV–visible irradiation. Furthermore, the results revealed that under visible irradiation, NiO-NPs inject electrons into the conduction band of titanium dioxide. Full article

A comparison of two synthesis methods for depositing Au nanoparticles onto TiO₂ was performed: (1) impregnation with HAuCl₄ followed by thermal treatment in argon, and (2) magnetron sputtering from a Au disc. The obtained materials were used for acetaldehyde decomposition in a high temperature reaction chamber and ch aracterised by UV-Vis/DR, XPS, XRD, SEM, and photoluminescence measurements. The process was carried out using an air/acetaldehyde gas flow under UV or UV-Vis LED irradiation. The mechanism of acetaldehyde decomposition and conversion was elaborated by in situ FTIR measurements of the photocatalyst surface during the reaction. Simultaneously, concentration of acetaldehyde in the outlet gas was monitored using gas chromatography. All the Au/TiO₂ samples showed absorption in the visible region, with a maximum around 550 nm. The plasmonic effect of Au nanoparticles was observed under UV-Vis light irradiation, especially at elevated temperatures such as 100 °C, for Au/TiO₂ prepared by the magnetron sputtering method. This resulted in a significant increase in the conversion of acetaldehyde at the beginning, followed by gradual decrease over time. The collected FTIR spectra indicated that, under UV-Vis light, acetaldehyde was strongly adsorbed onto Au/TiO₂ surface and formed crotonaldehyde or aldol. Under UV, acetaldehyde was mainly adsorbed in the form of acetate species. The plasmonic effect of Au nanoparticles increased the adsorption of acetaldehyde molecules onto TiO₂ surface, while reducing their decomposition rate. The increased temperature of the process enhanced the decomposition of the acetaldehyde. Full article

Photodynamic inactivation (aPDI) involves the interaction of three components: non-toxic photosensitizer molecules (PS), low-intensity visible light, and molecular oxygen. This interaction leads to the generation of toxic reactive oxygen species. The present work demonstrated the efficacy of light-induced antimicrobial photodynamic inactivation against Pseudomonas aeruginosa and Pseudomonas putida using 5-aminolevulinic acid (5-ALA) as a prodrug to produce the photosensitizer protoporphyrin IX. The photoeradication efficiency of these pathogens under blue (405 nm; 45 mW cm⁻²) and red (635 nm; 53 mW cm⁻²) light was investigated. Results showed that at least 30 min of blue light irradiation was necessary to achieve a 99.999% reduction of P. aeruginosa, whereas red light was less effective. P. putida exhibited limited susceptibility under similar conditions. To enhance aPDI efficiency, exogenous glucose was added alongside 5-ALA, which significantly increased the photodynamic efficacy—particularly against P. aeruginosa—leading to complete eradication after just 5 min of exposure. Spectroscopic analyses confirmed that glucose increased the levels of protoporphyrin IX, which correlated with enhanced photodynamic efficacy. Furthermore, multiple aPDI exposure reduced key virulence factors, including alkaline protease activity, biofilm formation, and swarming motility (in P. aeruginosa). These findings suggest that 5-ALA-mediated photodynamic inactivation offers a promising strategy to improve efficacy against resistant Gram-negative pathogens. Full article

This study explores the development and optimization of TiO₂-based photoactive coatings enhanced with silver (Ag)—to boost photocatalytic performance—for application on glass-fiber-reinforced polyester (GFRP) and epoxy (GFRE) composites. The influence of Ag content on the structural, physicochemical, and functional properties of the coatings was evaluated. The TiO₂-Ag coating showed the best performance and was tested under UV-A irradiation and visible light (Vis), with high efficiency in VOC degradation, self-cleaning, and microbial activity. The tests were repeated in multiple runs, showing high reproducibility in the results obtained. In GFRP, pollutant and microorganism removal ratios of more than 90% were observed. In contrast, GFRE showed a lower adhesion and stability of the coating. This result is attributed to incompatibility problems with the epoxy matrix, which significantly limited its functional performance. The results highlight the feasibility of using the TiO₂-Ag coating on GFRP substrates, even under visible light. Under real-world conditions for 351 days, the coating on GFRP maintained its stability. This type of material has high potential for application in modular building systems using sandwich panels, as well as in facades and automotive components, where self-cleaning and contaminant-control properties are essential. Full article

The Earth Radiation Budget (ERB), a measure of the difference between incoming solar irradiance and outgoing reflected and emitted radiant energy, is a fundamental property of Earth’s climate system. The Libera satellite mission will measure the ERB’s outgoing components to continue the long-term climate data record established by NASA’s Clouds and the Earth’s Radiant Energy System (CERES) mission. In addition to ensuring data continuity, Libera will introduce a novel split-shortwave spectral channel to quantify the partitioning of the outgoing reflected solar component into visible and near-infrared sub-components. However, converting these split-shortwave radiances into the ERB-relevant irradiances requires the development of split-shortwave Angular Distribution Models (ADMs), which demand extensive angular sampling. Here, we show how Rotating Azimuthal Plane Scan (RAPS) parameters—specifically operational cadence and azimuthal scan rate—affect the observational coverage of a defined scene and angular space. Our results show that for a fixed number of azimuthal rotations, a relatively slow azimuthal scan rate of 0.5° per second, combined with more time spent in the RAPS observational mode, provides a more comprehensive sampling of the desired scene and angular space. We also show that operating the Libera instrument in RAPS mode at a cadence between every fifth day and every other day for the first year of space-based operations will provide sufficient scene and angular sampling for the observations to achieve radiance convergence for the scenes that comprise more than half of the expected Libera observations. Obtaining radiance convergence is necessary for accurate ADMs. Full article

In this study, the BPTCD/g-C₃N₄ heterojunction photocatalyst was successfully prepared by the hydrothermal method. BPTCD (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) is immobilised on the surface of g-C₃N₄ by non-covalent π-π stacking. The BPTCD/g-C₃N₄ heterojunction photocatalyst is an all-organic photocatalyst with significantly improved photocatalytic performance compared with g-C₃N₄. BPTCD/g-C₃N₄-60% was able to effectively degrade MO solution (10 mg/L) to 99.9% and 82.8% in 60 min under full spectrum and visible light. The TOC measurement results indicate that MO can ultimately be decomposed into H₂O and CO₂ through photocatalytic action. The photodegradation of methyl orange by BPTCD/g-C₃N₄ composite materials under sunlight is mainly attributed to the successful construction of the heterojunction structure and its excellent π-π stacking effect. Superoxide radicals (^•O₂⁻) were found to be the main active species, while ^•OH and h⁺ played a secondary role. The synthesised BPTCD/g-C₃N₄ also showed excellent stability in the activity of photodegradation of MO in wastewater, with the performance remaining above 90% after three cycles. The mechanism of the photocatalytic removal of MO dyes was also investigated by the trap agent experiments. Additionally, BPTCD/g-C₃N₄-60% demonstrated exceptional photodegradation performance in the degradation of methylene blue (MB). BPTCD/g-C₃N₄ heterojunctions have great potential to degrade organic pollutants in wastewater under solar irradiation conditions. Full article