Search Results (370)

Hydrogen is increasingly recognized as a key energy carrier for decarbonizing hard-to-electrify sectors, yet more than 95% of current global production remains fossil-derived. Biological hydrogen (biohydrogen) produced by dark fermentation (DF), photo-fermentation (PF), or microbial electrolysis cells (MEC) offers the dual advantage of valorizing organic wastes while delivering low-carbon H₂; however, none of these standalone technologies mobilizes more than 25–33% (DF), 40–70% (PF), or 40–60% (MEC) of feedstock organic carbon through H₂-producing oxidation pathways. Most existing reviews compare these pathways on hydrogen yield alone, a metric that conceals where the majority of feedstock carbon and electrons are actually lost and obscures the quantitative rationale for system integration. This review reframes the comparison around carbon and electron flow, explicitly tracking how much input carbon is mobilized through H₂-producing oxidation pathways, how much is retained in volatile fatty acids (VFAs), biomass, or unlinked CO₂, and what happens to the associated electrons. Stoichiometric, mechanistic, and reactor-level evidence is synthesized to show that DF channels only 25–33% of input organic carbon through H₂-yielding decarboxylation on real heterogeneous substrates, with 40–60% retained as residual VFAs and unhydrolyzed solids; PF can recover 60–80% of VFA carbon but is constrained by photon economics and nitrogenase sensitivity; and MEC achieves >85% COD removal only when coupled to an upstream acidogenic stage. Two-stage (DF–PF, DF–MEC) and three-stage (DF–PF–MEC, DF–MEC–AD) configurations are critically evaluated, with theoretical yields separated from experimentally demonstrated performance on real wastes and hidden energy inputs (pretreatment, inter-stage transfer, gas separation, and compression) explicitly accounted for. DF–MEC coupling is identified as the most near-term tractable configuration, achieving 55–70% H₂-pathway carbon mobilization and 80–92% COD removal at an electrical input of 0.9–1.5 kWh/m³ H₂, with levelized hydrogen costs of US$3–5.5/kg under favorable waste-tipping-fee conditions. Multi-stage systems push carbon recovery above 70% but carry unresolved capital, methanogenesis control, and scale-up penalties. This review closes by proposing a standardized ten-descriptor reporting framework including H₂-pathway carbon mobilization (%), cathodic hydrogen recovery (rCAT), net energy recovery (NEB), and LCA carbon intensity under both attributional and consequential boundaries, and demonstrates its backward compatibility by retrospective application to seven studies already in the literature. Research priorities tractable on a 5–10 year horizon are identified, centered on methanogen suppression at pilot scale, real-waste MEC performance, and renewable-electricity coupling. Full article

This study investigates the impact of clinically relevant sterilization methods, such as ethylene oxide (EtO), gamma (γ) irradiation, autoclaving, and hydrogen peroxide gas plasma, on the physical, structural, and functional properties of methacrylated silk fibroin hydrogels obtained by photo- and enzymatic crosslinking. EtO, γ irradiation, and hydrogen peroxide gas plasma were applied as terminal sterilization methods to the fabricated hydrogels, whereas autoclaving was performed on the SilMA precursor solution prior to hydrogel formation. Silk fibroin hydrogels at 5 and 7 wt.% concentrations were evaluated for transparency, rheological behavior, water content, secondary structure, chemical composition, thermal stability, microbial growth, and morphology after sterilization and during storage. EtO sterilization effectively maintained high optical transparency (>98%) but compromised the mechanical properties of the hydrogels. In contrast, γ-irradiation and autoclaving promoted greater β-sheet formation, resulting in increased mechanical stiffness and thermal stability but reduced transparency after autoclaving. Plasma sterilization proved unsuitable, as incomplete cycles related to the high-water content of hydrogels. Overall, the results delineate the influence of different sterilization strategies and identify approaches that best preserve or enhance the performance of silk hydrogels, supporting their clinical translation in tissue engineering. Full article

The interfacial behavior of hybrid nanoparticles on biological substrates governs their functional performance. Here, we investigate how surface properties and colloidal stability dictate the pH-dependent adhesion of oxybenzone-loaded palygorskite nanohybrids to hair—a model biological interface. A series of hybrids with 5–50% oxybenzone loadings were prepared via melt impregnation. XRD and FTIR analyses confirm hydrogen bonding between oxybenzone and palygorskite, forming stable organic–inorganic hybrids. The colloidal stability of these nanohybrids varies non-monotonically with oxybenzone loading, governed by surface hydrophilicity and zeta potential, exhibiting a network-like behavior upon pH change. Optimal stability is achieved at an intermediate loading with a favorable balance of surface properties. While pristine hybrids show no affinity for hair, surface modification with cationic polyquaternium-7 (PQ-7) or non-ionic polyvinylpyrrolidone (PVP) enables effective deposition through distinct pH-dependent mechanisms: PQ-7 operates optimally at pH 10 via electrostatic attraction, whereas PVP performs best at pH 4 through hydrogen bonding, forming a protective coating layer on the hair surface. Deposition fails for PVP-modified hybrids at 50% loading due to excessive surface hydrophobicity. The deposited hybrids provide exceptional UV protection, significantly mitigating cuticle damage, suppressing photo-yellowing, and minimizing protein oxidation. Among the hybrids, hybrid-35 exhibited the best colloidal stability, whereas PQ-7-modified hybrid-50 gave the highest UV protection (color difference ΔE reduced from 10.51 to 1.60). The adhesion rates of the two best-performing hybrids were 2.70% and 2.85%, respectively. Beyond hair protection, we evaluate the environmental interface of these materials. While free oxybenzone is highly toxic to Chlorella vulgaris, hybridization drastically reduces its ecotoxicity. Remarkably, palygorskite and the hybrids promote algal growth, likely by acting as nutrient adsorbents and attachment sites. This work provides fundamental insights into particle–biointerface interactions and offers a strategy for designing functional hybrid materials with tailored surface properties for bio-related applications. Full article

The integration of artificial intelligence (AI), machine learning (ML), and computational modeling with experimental catalysis is reshaping materials design and chemical process development. Tailored heterogeneous catalysts including supported metals, zeolites, defect-engineered materials, and multi-element systems exhibit enhanced activity, selectivity, and stability through engineered active sites and porosity. AI and ML approaches enable predictive modeling, high-throughput screening, mechanistic insight, and rational catalyst design by linking synthesis conditions, structural features, and performance metrics across scales. Applications span CO₂ conversion, methane reforming, hydrogen production, polymer recycling, and photocatalysis, with platforms such as PHOTOREAC, QMOF, and PhotoCatDB facilitating the translation from laboratory experiments to reactor-scale processes. Hybrid strategies that combine mechanistic understanding with data-driven models improve interpretability, predictive accuracy, and process optimization. These advances underscore a paradigm shift toward data-driven catalysis, accelerating discovery, supporting sustainable chemical technologies, and emphasizing the role of human expertise in guiding responsible AI deployment. Full article

In this study, polyhedral self-assembled spherical titania (TS) photocatalyst was successfully synthesized via a one-step hydrothermal method from titanium chloride, sodium dodecyl sulfate and sulfuric acid. Titania modification with iron was carried out through the same procedure by the addition of different amounts of iron(III) chloride to the substrate mixture. Various methods were applied for sample characterization, e.g., XRD, SEM, TEM, XPS, UV-vis DRS, and photo-electrochemical measurements, such as EIS, CV, transient photocurrent, whereas photocatalytic activity was investigated for hydrogen evolution under UV/vis and oxidative decomposition of antibiotics under UV and/or vis, including also tests with scavengers. It has been found that iron was both incorporated in the titania structure (doping) and adsorbed on its surface. Although iron presence has hardly influenced the properties (slight changes in morphology, bandgap energy, and crystallite size), the photocatalytic activity has increased significantly. Therefore, it is proposed that iron might work as an electron sink, hindering the charge carriers’ recombination. Linear evolution of hydrogen, recycling experiments and characterization of samples after recycling have confirmed a good stability of iron-modified titania. Full article

The present study investigates the solar-assisted photo-Fenton-like degradation of a reactive azo dye (Red SPR) using an iron-based metal–organic framework, MIL-100(Fe), as a heterogeneous catalyst. The synthesized MIL-100(Fe) was successfully characterized by XRD, SEM, EDX, and FTIR analyses, confirming the formation of a crystalline, porous structure with well-dispersed Fe active sites. The catalytic performance was systematically evaluated under various operational parameters, including hydrogen peroxide dosage, catalyst loading, pH, circulation flow rate, initial dye concentration, and temperature. The results demonstrated that optimal degradation efficiency was achieved at pH 3.0, H₂O₂ concentration of 400 mg L⁻¹, and catalyst dosage of 40 mg L⁻¹, while a circulation flow rate of 400 mL min⁻¹ ensured optimal hydrodynamic conditions. The system exhibited rapid degradation kinetics, achieving nearly complete dye removal within 60 min under solar irradiation. Kinetic analysis revealed that the degradation process follows pseudo-first-order behavior, with rate constants increasing from 0.1040 to 0.1589 min⁻¹ as temperature increased from 25 to 55 °C. Thermodynamic analysis indicated that the process is endothermic (ΔH` = 8.72 kJ mol⁻¹) and kinetically favorable with a low activation energy (Ea = 11.32 kJ mol⁻¹), while negative entropy values suggested the formation of an ordered transition state. Radical scavenger experiments confirmed that hydroxyl radicals (•OH) are the dominant reactive species, with secondary contributions from superoxide radicals (O₂•⁻). The enhanced performance is attributed to the synergistic effect of solar irradiation and Fe³⁺/Fe²⁺ redox cycling within the MIL-100(Fe) framework. Hence, the study demonstrates that MIL-100(Fe) is a highly efficient and sustainable catalyst for solar-driven wastewater treatment applications. Full article

Hydroxygallium phthalocyanine type V (HOGaPc V) is an excellent photo generator and is applied in xerography. The material is only accessible as polycrystalline substances, and the crystal structure for an evaluation of the structure–property relationship cannot be determined from the few X-ray reflections available by powder X-ray pattern. A new method for crystal structure determination is introduced, utilizing molecular interactions. This proposed structure appears to be superior to the published one by the classical application of the Rietveld analysis. Hydrogen bonds are detected and explain the thermal stability, combined with high photosensitivity, and point towards favorable application in electrophotography. A triclinic two-molecule unit cell P-1 with a = 11.63 Å, b = 12.60 Å, c = 8.88 Å, α = 95.7°, β = 95.2°, γ = 69.1° was established close to the one verified by the Rietveld analysis. The structure obtained was successfully tested by a comparison of the observed contacts and the packing energy of known Pc single-crystal structures and by a similar X-ray residual R factor of the mostly overlapping reflections with other materials. The packing contacts of the crystal determined by the Rietveld analysis show too short contacts and too high packing energies. The molecular and crystal structure of HOGaPc V is represented and discussed. Full article

Silk fibroin (SF)–polyphenol systems have emerged as a versatile class of gels and hydrogels in which supramolecular interactions and dynamic crosslinking regulate network formation, responsiveness, and multifunctional performance. Polyphenols interact with SF through hydrogen bonding, hydrophobic interactions, π–π stacking, metal coordination, and covalent crosslinking, thereby modulating conformational transitions, gelation behavior, structural stability, and interfacial functionality. These interaction mechanisms enable the development of SF–polyphenol gel systems with tunable mechanical properties, wet adhesion, antioxidant activity, self-healing capability, and stimuli responsiveness. This review summarizes recent advances in SF–polyphenol gels and hydrogels, with particular emphasis on molecular interaction mechanisms, gelation and fabrication strategies, responsive behaviors, and structure–property relationships. Representative preparation approaches, including solution blending, electrospinning, impregnation–adsorption, enzymatic crosslinking, metal–phenolic coordination, and photo-initiated processing, are systematically discussed in relation to their effects on network architecture and functional output. The responsive behaviors of these systems under pH, redox, electrical, thermal, and optical stimuli are also analyzed from the perspective of dynamic gel networks and adaptive material design. Emerging applications of SF–polyphenol gels in bioadhesives, delivery platforms, flexible bioelectronics, wound-related materials, and sustainable functional systems are highlighted. Current limitations associated with polyphenol instability, formulation sensitivity, reproducibility, and scale-up are critically discussed, together with future opportunities for predictive design of gel-based natural polymer systems. This review provides a comprehensive framework for understanding SF–polyphenol gelation and for guiding the development of next-generation multifunctional gels and hydrogels. Full article

The performance and mechanism of heterogeneous catalytic reactions are fundamentally governed by the formation, stability, and reactivity of transient surface intermediates. These species—such as isocyanates, alkyl groups, carboxylates, formates, carbonates, alkoxy and acyl intermediates—often exist at low concentrations and with short lifetimes, making their identification challenging. This review summarizes the current knowledge on the formation, spectroscopic identification, and thermal behavior of these intermediates on metal single crystals, metal nanoparticles, and oxide-supported catalysts. Emphasis is placed on key reactions including CO and NO oxidation–reduction, CO and CO₂ hydrogenation, Fischer–Tropsch-related pathways, and reforming of ethanol. Advanced surface-sensitive techniques (TDS, XPS, UPS, IR, HREELS) are highlighted for their role in elucidating intermediate structures and reaction pathways. The isocyanate surface complex is an existing intermediate in NO reduction with CO, and NCO is responsible for NH₃ formation. Alkyl groups can be prepared from thermal- or photo-induced dissociation of alkyl halogenide. Oxygen-containing intermediates relevant to CO₂ hydrogenation are addressed, with particular attention to formate, carboxylate, and related species. M/CeO₂ (M = Pt, Rh, Ir, Ru) seems to be the best catalyst for hydrogen production from ethanol reforming. The nature of support may affect hydrogen production. The review also discusses how metal–support interactions, particle size, and surface morphology influence intermediate stability and catalytic selectivity. Overall, the work provides a comprehensive framework for understanding how transient surface complexes control technologically important catalytic transformations. Full article

This work reports on the synthesis and electrochemical investigation of sustainable carbon–TiO₂ nanocomposites derived from marine biowaste, designed to elucidate light-assisted charge storage mechanisms in non-aqueous electrolytes. Porous carbons obtained from prawn chitin and blue shark gelatin were decorated in situ with TiO₂ nanoparticles using a deep eutectic solvent (DES) as a green synthesis medium. Structural and morphological characterisation revealed that TiO₂ incorporation induces significant nanoscale reorganisation of the carbon framework, resulting in hierarchical porosity, increased surface area, and intimate semiconductor–carbon interfaces. Electrochemical evaluation in a three-electrode configuration using an ethaline-based DES electrolyte demonstrated that TiO₂ decoration substantially enhances capacitive performance and cycling stability, with the prawn chitin-derived composite achieving a specific capacitance of 54 ± 3 F g⁻¹ and 91% retention after 10,000 cycles. Under illumination, all TiO₂-containing composites exhibited a pronounced increase in anodic current response and discharge time, indicating photo-assisted surface charge accumulation. Although the absolute capacitance values are modest compared to those of aqueous supercapacitor systems, the results provide mechanistic insight into the interplay among nanostructure, semiconductor photoactivity, and ion transport in viscous, hydrogen-bonded DES electrolytes. By combining waste-derived carbons, green synthesis routes, and photo-responsive nanostructures, this study highlights a sustainable strategy for developing multifunctional carbon-based nanomaterials with light-modulated electrochemical behaviour. Full article

The photoelectrochemical water-splitting process for hydrogen production is limited by the large bandgap of semiconductor titanium dioxide (TiO₂) and by interfacial recombination at particle interfaces. The technique used in this paper is that of electrochemical anodization to produce robust, ordered TiO₂ nanotube arrays (TiO₂ nanorod arrays denoted as TNTAs). Using the immersion-annealing method, Nd₂O₃ nanoparticles can be immobilized in situ, and Nd₂O₃/TNTAs composite photoanodes are fabricated. The heterointerface caused between the Nd₂O₃ nanoparticles and TiO₂ results in the alignment of the Fermi levels and the formation of band bending and an internal electric field at the interface. It allows rapid photo-generated electron-hole (e⁻/h⁺) separation at the interface and, simultaneously, introduces novel localized electron states of Nd³⁺ within the TiO₂ bandgap. This triggers hybridisation between the 3d orbitals of Ti and the 2p orbitals of O, thereby altering the band structure of TiO₂. The best-performing Nd₂O₃/TNTAs photoelectrode outperforms pure TNTAs, with a photocurrent density of 1.59 mA·cm⁻² at 1.23 V vs. RHE. It produces 162.6 μmol·cm⁻² of hydrogen in a 3 h photocatalytic hydrogen production experiment, which is about 12.2 times that of pure TNTAs. This approach highlights the unique benefits and creative opportunities of applying rare-earth elements to address the critical issues of photocatalysts, such as significant band gaps and rapid recombination. Full article

Oxidative stress induced by excessive hydrogen peroxide (H₂O₂) is a critical pathological factor in skin aging, inflammatory disorders, and photodamage. While tocopherol (TCP) is a gold-standard antioxidant in cosmetics, its potential in H₂O₂-responsive systems remains underexplored. In this study, we report the design and characterization of ditocopheryl peroxalate (TOT), a novel tocopherol dimer linked via a H₂O₂-cleavable peroxalate linkage. TOT remains chemically stable under physiological conditions but undergoes selective chemiluminescence-like degradation upon exposure to H₂O₂, simultaneously scavenging H₂O₂ and liberating two TCP molecules. Notably, TOT demonstrated superior H₂O₂-scavenging efficiency and enhanced antioxidant and anti-inflammatory effects in H₂O₂-stimulated cells compared to monomeric TCP, while maintaining excellent biocompatibility. Structural analysis revealed that the rigid, linear configuration of TOT facilitates seamless integration into dipalmitoylphosphatidylcholine (DPPC) bilayers, yielding highly stable H₂O₂-responsive liposomes. These findings highlight TOT as a sophisticated multifunctional antioxidant platform for advanced cosmeceutical applications targeting photo-induced oxidative damage. Full article

Our recent work has focused on red light-mediated photoreduction of p-benzoquinones and both o-, and p-naphthoquinones using methylene blue and the chlorophyll metabolite, pheophorbide A as photosensitizers. Photoreduction of biologically relevant quinones mimics photoreduction of plastoquinone by chlorophyll in photosynthesis. We examined photo-oxidation and photoreduction reactions of catechols because their oxidation to o-quinones by reactive oxygen species is implicated in protein damage in neurodegeneration. Photo-oxidation of catecholamines including dopamine, epinephrine and norepinephrine required red light, methylene blue or pheophorbide A, and molecular oxygen. Their cyclized oxidation products, aminochrome, adrenochrome and noradrenochrome, were detected by UV/visible spectroscopy. Hydrogen peroxide was generated during photo-oxidation by singlet oxygen-dependent oxidation of catecholamines. Inclusion of tertiary amine electron donors decreased cyclized products but did not affect hydrogen peroxide yield consistent with concurrent photo-oxidation followed by photoreduction of the o-quinone intermediate. Unreacted dopamine and norepinephrine were quantified using 3-hydroxyphenyl boronic acid following photochemical reactions. Dopamine and norepinephrine boronate esters absorb at 417 and 550 nm. Photo-oxidation of dihydroxycaffeic acid and dihydroxyphenyl acetic acid was also evaluated by detecting their boronate esters at 475 nm. We hypothesize that photoreduction of transient o-quinones by the combination of red light and dietary chlorophyll metabolites may be a path to limit protein damage and to recycle catechol antioxidants. Full article

A carbon-modified attapulgite composite (C-AATP@CTAB) was synthesized via the hydrothermal method using citric acid as the carbon source and cetyltrimethylammonium bromide (CTAB) as a surface modifier for efficient rhodamine B (Rh-B) removal. Carbon modification elevated the composite’s specific surface area (212 m²/g) and negative surface charge (−38.21 mV), significantly enhancing dye adsorption capacity to 666.66 mg/g—nearly double that of unmodified ATP variants (360.4–386.8 mg/g). Kinetic studies confirmed pseudo-second-order adsorption kinetics, attributed to hydrogen bonding and van der Waals interactions between Rh-B and the composite. Under photo-Fenton conditions, C-AATP@CTAB achieved 99.8% Rh-B degradation within 20 min, demonstrating superior catalytic performance in heterogeneous Fenton/photo-Fenton systems. This work establishes a low-cost, high-efficiency adsorbent-catalyst hybrid derived from low-grade attapulgite, offering promising avenues for sustainable wastewater treatment. Full article

A well-defined heterojunction and tailored interface of the photocathode are desired to facilitate the efficient separation and transfer of photogenerated charge carriers for photoelectrochemical (PEC) hydrogen generation. Herein, optimized Z-scheme heterojunction (denoted as F-COF/TiO₂) photoelectrodes were designed and fabricated by solvothermally growing a F-substituted imine-linked covalent organic framework (F-COF) from 1,3,5-tris(3-fluoro-4-formylphenyl)benzene and 1,4-diaminobenzene on the surface of anodized TiO₂ nanotubes for enhanced PEC hydrogen evolution. The F-COF/TiO₂ heterojunction with photo-deposited Pt species as cocatalysts (Pt@F-COF/TiO₂) revealed higher cathodic photocurrent density, decreased interfacial resistance, and improved onset potential due to the improved charge separation and transfer efficiency at the interface. Both the internal electric field between F-COF and TiO₂, as well as the enhanced photophysical nature of F-COF films, contributed to the efficient interfacial charge separation and transfer. The photo-deposited Pt species and applied bias voltage also demonstrated a synergetic effect on facilitating charge separation and transfer for hydrogen production. The Pt@F-COF/TiO₂ photoelectrode featured an improved PEC hydrogen evolution rate under AM 1.5G simulated sunlight irradiation and a durable PEC hydrogen evolution performance. This study provides valuable insights into the design of heterojunction-based photoelectrodes for efficient solar-driven hydrogen production for sustainable energy applications. Full article