Search Results (514)

The modern world is confronting critical environmental and biomedical challenges, underscoring the urgent need for the development of multifunctional materials—an inherently interdisciplinary field, bridging materials science and engineering, environmental science and biomedicine. Titanium dioxide (TiO₂) is widely recognized for its photocatalytic and antiviral properties, enabling the degradation of pollutants and mitigation of viral contamination under solar irradiation. Nevertheless, it exhibits certain limitations, such as wide band gap and high recombination rate of photogenerated electron–hole pairs. To address these limitations, TiO₂ prepared by a co-precipitation method was modified with N-Doped Carbon Dots (N-CDs) via a hydrothermal treatment, which extend light absorption into the visible region and enhance charge separation. Further functionalization with silver nanoparticles (Ag NPs)—well known for their antimicrobial properties—via a simple thermal process under ambient conditions, introduced additional reactive oxygen species generation, creating a synergistic effect. The as-prepared TiO₂, TiO₂/N-CDs and TiO₂/N-CDs/Ag samples were characterized via several techniques, such as XRD, micro-Raman, FT-IR, TEM and UV-Vis. In addition, their photocatalytic and antiviral activity against methylene blue (MB) and nitrogen oxide (NO_x) pollutants, as well as SARS-CoV-2, was evaluated. Based on the results of liquid-phase photocatalysis, TiO₂, TiO₂/N-CDs and TiO₂/N-CDs/Ag presented a degradation efficiency of 78%, 85% and 95%, respectively, whereas different trends were observed under gaseous-phase conditions. The TiO₂/N-CDs/Ag hybrid material demonstrated superior antiviral activity against SARS-CoV-2 (IC₅₀: 1.24 ± 0.34 g/L), compared to both TiO₂ (IC₅₀: 1.78 ± 0.30 g/L) and TiO₂/N-CDs (IC₅₀: >2.5 g/L), highlighting its potential as an effective multifunctional material. Finally, TiO₂/N-CDs/Ag was incorporated onto a paper substrate, demonstrating antiviral activity, showing promising scalability for application across a wide range of future substrates. To the best of our knowledge, this is the first study presenting TiO₂/N-CDs/Ag with dual photocatalytic and antiviral activity. Full article

This paper presents a theoretical engineering feasibility analysis of the RK-X photocatalytic process for In Situ Resource Utilisation (ISRU) on Mars. Experimental validation under simulated Martian conditions is the essential next step before any mission deployment claim can be made. The RK-X process converts the two most abundant Martian resources, atmospheric carbon dioxide (CO₂) and subsurface water ice (H₂O), into formic acid (HCOOH) and oxygen (O₂) through a fulvic acid-based photocatalytic cycle validated at the industrial scale in Hungary. A reference module processing 10 tonnes of CO₂ per Earth year yields 10.459 tonnes of formic acid and 3.636 tonnes of oxygen, sufficient to sustain a six-person crew for approximately two Earth years with a 198% safety margin over nominal respiratory demand. The economic analysis indicates that importing equivalent oxygen from Earth costs $1.82–$3.64 million per year; equivalent energy storage (Li-ion) costs $30.5–$61 million for one-time use. Formic acid stores 15.25 MWh of energy in ambient-stable liquid form at a round-trip efficiency of 68.64% without cryogenic infrastructure. A photovoltaic array of 55.37 m² provides the primary energy source; a kilowatt-class nuclear fission reactor constitutes the strategic opportunity for continuous, dust-storm-immune operation with free thermal co-generation. Three critical research gaps have been identified requiring laboratory validation before Mars deployment: (i) catalyst performance at the Martian CO₂ partial pressure (p(CO₂) < 10 mbar, T = 15 °C); (ii) water ice and dry ice extraction at an operational scale; and (iii) integrated closed-loop system demonstration. Built on Earth-proven chemistry with identified, addressable development pathways, the RK-X process theoretically resolves the problems of oxygen supply, seasonal energy storage, water management, and cryogenic infrastructure within a single closed-loop chemical cycle. Full article

Hexagonal boron nitride (h-BN) is a chemically stable two-dimensional material whose wide band gap and low surface reactivity limit its performance in adsorption and photocatalysis, motivating strategies to tailor its structure. In this work, a mechanochemical approach combining high-energy ball milling with NaOH-assisted treatment was used to induce simultaneous exfoliation and hydroxylation of h-BN, promoting defect generation, reduced crystallinity, interlayer expansion, and incorporation of oxygen-containing groups (B-OH and B-O). These modifications led to band gap narrowing, increased surface polarity, and improved dispersion, enabling the formation of heterogeneous active sites. The hydroxylated material (BN-OH) exhibited high adsorption capacities of 248 mg/g for methylene blue (MB) and 215 mg/g for rhodamine 6G (R6G), following Freundlich behavior, indicative of heterogeneous adsorption governed by electrostatic interactions, π–π stacking, hydrogen bonding, and defect-mediated sites. Under solar irradiation, BN-OH achieved up to 99% degradation of both dyes, following predominantly pseudo-first-order kinetics and outperforming pristine BN; additionally, the kinetic behavior under solar conditions was successfully described using the Behnajady–Modirshahla–Ghanbary (BMG) model, which accurately predicts the two-stage degradation process. Scavenger experiments revealed that ⦁OH radicals dominate MB degradation, while ⦁OH, O₂⦁⁻, and h⁺ contribute to R6G removal. Overall, defect engineering and hydroxyl functionalization synergistically enhance photocatalytic performance, providing a scalable strategy for wastewater treatment. Full article

Hafnia (hafnium oxide) nanostructures, both unmodified and silica-modified with minor and major silica content, were synthesized using an adapted sol–gel method with D-L tartaric acid as an internal template. After thermal treatment, structural non-stoichiometry and light absorptive properties were identified in the resulting hafnium-based nanostructures, indicating their potential for various applications, including photocatalysis. The ability of these materials to photogenerate reactive oxygen species (ROS), namely superoxide anion radicals (•O₂₋) under simulated solar light (AM 1.5) and singlet oxygen (¹O₂) under visible light (λ > 390 nm), was evaluated and monitored by UV–Vis and photoluminescence spectroscopy. Functionalization of hafnium-based oxides with protoporphyrin IX was employed to enhance singlet oxygen photogeneration. The reactivity of the generated (¹O₂) was assessed by quenching of DL α-tocopherol photoluminescence under visible light irradiation. Photocatalytic experiments conducted under anaerobic conditions demonstrated the ability of the hafnia-based nanostructures to reduce 1,4-benzoquinone (BQ) to 1,4-hydroquinone (H₂Q). Furthermore, embedding the hafnia-based powders into polyvinyl alcohol hydrogels enabled the obtainment of photoactive coatings on glass substrates, for which their mechanical properties were evaluated using force–distance spectroscopy measurements. Morphological and structural characterization of the materials was performed using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction and fluorescence (XRD, XRF), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption measurements, UV–Vis spectroscopy, photoluminescence (PL) spectroscopy, and zeta potential measurements. These investigations revealed that adding silica induces significant modifications in the morphology, texture, and structure of the hafnia, thereby enhancing the functional properties of the resulting materials. Full article

Pollution by persistent organic pollutants (POPs) constitutes an environmental and public health crisis of planetary scale due to their toxicity, persistence, and capacity for bioaccumulation in ecosystems. Given the limitations of conventional methods, which are often costly or generate hazardous byproducts, advanced oxidation processes (AOPs) have emerged as critical alternatives for the terminal destruction of these compounds. However, a persistent gap remains between laboratory-scale innovations and their real industrial application. To address this issue, the study employs a systematic and quantitative bibliometric analysis of the scientific literature produced between 2000 and 2026. A total of 5911 documents indexed in Scopus were analyzed using specialized tools such as R Studio (bibliometrix) 2026.04.0+526 and VOSviewer (1.6.20) to map productivity, impact, and the intellectual structure of the field through co-occurrence networks and international collaboration. The results demonstrate exponential growth in research, with an annual rate exceeding 18%. China leads scientific production with 109 publications, while Spain and France record the highest impact per article, with averages of 217.5 and 213.5 citations respectively, underscoring the influence of their researchers as theoretical and methodological benchmarks. Authors such as Malato (Spain) and Oturan (France) act as central nodes of international collaboration, accumulating thousands of citations in areas such as solar photocatalysis and electro-Fenton processes. The analysis confirms that solar photocatalysis and electrochemical processes are the most effective AOP families, consistently reporting degradation efficiencies above 85–90%. Wastewater treatment is identified as the primary research driver, while advanced catalyst design has evolved into a niche technical specialization. Journals such as Chemosphere and Science of the Total Environment have consolidated as the main dissemination channels for this research. Full article

Piezo-enhanced photocatalysis is progressively considered an eco-friendly technology for contaminant removal, harvesting not only solar energy but also mechanical vibrations found in nature. Multiferroic materials present a coupled effect of various properties and can potentially increase the applicability of this process. In this study, Cr- doped bismuth ferrite thin film was deposited on SrTiO₃ substrate by HiPIMS, and its photo-, piezo-, and piezo-photocatalytic efficiencies in Rhodamine B (RhB) degradation were analyzed. The highest removal percentage was found under the simultaneous exposure of visible light and mechanical vibrations, reaching 86.2% after 180 min. The calculated efficiencies for photo- and piezocatalysis were 12.2% and 83.7%, respectively. The rate constant (k) for piezo-photocatalysis was 16.1 times higher than that found during photocatalytic experiments. To assess the contribution of each reactive species to the decomposition process, different reagents were added to the Rhodamine B contaminated solution. The results revealed that when p-benzoquinone was used, the degradation efficiency declined significantly from 86.2% to 37.6%, suggesting that superoxide radicals (O₂^•−) play a key role in decomposing RhB molecules. The structural, chemical, optical, and ferroelectric changes caused by the catalytic processes were analyzed and linked to the proposed degradation mechanisms. The poor photocatalytic efficiency was linked to an improper band structure and an improper polarization orientation of the ferroelectric domains in the as-deposited film. The degradation mechanisms in piezo-photocatalysis were driven partly by the band bending caused by mechanical vibrations and partly by the reorientation of the induced polarization of the domains in the unstrained film. Full article

Photocatalytic hydrogen production represents a promising approach for sustainable fuel generation, particularly when driven by solar irradiation. In this study, a photocatalytic system composed of eosin Y, cobalt sulfate, triethanolamine, and graphene oxide was investigated for hydrogen evolution. The optical and structural properties of the system components were characterized using UV–Vis spectroscopy, FT-IR spectroscopy, Raman spectroscopy, and atomic force microscopy. Photocatalytic activity was evaluated under both artificial light sources (halogen lamp, xenon lamp, and LED 505 nm) and natural sunlight in order to assess system performance under realistic environmental conditions. The addition of graphene oxide significantly enhanced hydrogen production, resulting in an approximately 4-fold increase compared to the three-component system without graphene oxide. Solar-driven experiments conducted over one year demonstrated efficient hydrogen evolution under a wide range of weather and irradiance conditions. Importantly, based on combined experimental and meteorological data, it is shown that high photocatalytic performance is achievable for a substantial fraction of the year, with approximately 55% of days expected to provide at least 80% of the maximum hydrogen production efficiency under Central European climatic conditions. These findings highlight the strong potential of the investigated four-component system for efficient hydrogen generation using low amounts of catalytic material and without external electrical energy input. Overall, the system shows promising performance for solar-driven hydrogen production under real-world solar irradiation conditions. Full article

This study examines the solar-driven photocatalytic degradation of tetracycline hydrochloride in aqueous media using immobilized magnetite. The synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). Photocatalytic experiments revealed that tetracycline degradation followed pseudo-first-order kinetics, achieving 48% removal within 30 min and nearly complete degradation (99%) after 120 min of solar irradiation. The addition of Fenton reagent significantly enhanced degradation efficiency by promoting the generation of reactive oxygen species. The formation of multiple degradation intermediates, along with a substantial reduction in chemical oxygen demand (COD) was observed. The immobilized magnetite catalyst exhibited good stability and reusability with minimal loss of activity over repeated cycles. Overall, the results demonstrate that magnetite-based solar photocatalysis is a cost-effective, efficient, and environmentally sustainable approach for treating TCT-contaminated wastewater. Full article

Increasing water demand and the rising complexity of wastewater matrices, driven by pharmaceuticals, personal care products, and recalcitrant industrial contaminants, require advanced catalytic solutions capable of efficient mineralization under sustainable conditions. Solar-driven processes have attracted growing attention; however, ultraviolet disinfection, heterogeneous photocatalysis, and photo-Fenton systems are commonly treated as independent approaches without mechanistic integration. This review presents a unified photonic–thermal catalytic framework for solar-driven wastewater treatment, emphasizing the interplay between photon absorption, charge-carrier separation, reactive oxygen species generation, and radical-mediated oxidation pathways. The contributions of ultraviolet, visible, and infrared radiation are analyzed in terms of catalyst activation, persulfate and ozone activation mechanisms, and temperature-enhanced reaction kinetics governed by Arrhenius behavior. Particular attention is given to photothermal effects that modulate surface reaction rates, mass transfer, and catalyst stability. By integrating mechanistic insights with reactor-level considerations, this work provides a rational basis for the design of robust solar catalytic systems with enhanced activity, selectivity, and scalability for real wastewater applications. Full article

A one-pot green combustion route was developed for the synthesis of ashy single-crystalline NiO nanoparticles using date molasses as a biogenic fuel and complexing medium. The obtained DM–NiO showed phase-pure cubic NiO with an average crystallite size of about 18 nm, a mesoporous texture with a BET surface area of 68.9 m² g⁻¹, a pore volume of 0.59 cm³ g⁻¹, an average pore diameter of 17.6 nm, and a mean particle size of 43.6 ± 8.13 nm. Optical characterization revealed defect-mediated light absorption with an energy gap of 3.11 eV, supporting solar-light-driven activity. In the photocatalytic degradation of pyronin Y, the catalyst exhibited strong pH dependence, reaching its best H₂O₂-free performance at pH 11 with a pseudo-first-order rate constant of 0.0072 min⁻¹, nearly six times higher than that at pH 3. The introduction of H₂O₂ markedly intensified the process, and at 9 mM H₂O₂, the rate constant increased to 0.048 min⁻¹, representing more than a sixfold enhancement over photocatalysis alone, while complete disappearance of the main visible absorption band was achieved within 38 min under solar illumination. Radical trapping experiments identified photogenerated holes and hydroxyl radicals as the dominant oxidative species. The catalyst also retained high activity over four successive cycles, with degradation efficiencies decreasing only slightly from 91.8% to 85.7%. These results demonstrate that date-molasses-assisted combustion synthesis provides a sustainable route to defect-active mesoporous NiO with highly enhanced solar photo-Fenton-like performance for dye-contaminated wastewater treatment. Full article

Heterogeneous photocatalysis is one of the most versatile and widely studied photochemical approaches for the degradation of recalcitrant pollutants. Owing to its favorable physicochemical properties, titanium dioxide (TiO₂) remains one of the most investigated semiconductor photocatalysts. However, its wide band-gap energy (3.2 eV) restricts its photoactivity to the UV region, which represents only a small fraction of the solar spectrum. A major challenge in this field is therefore the development of TiO₂-based materials capable of operating efficiently under visible light irradiation, enabling the use of solar energy as a sustainable primary source. Several strategies have been explored to extend the optical response of TiO₂, among which elemental doping remains one of the most effective and commonly applied. In this work, we conducted systematic comparative analysis to evaluate the photocatalytic performance of TiO₂ modified through different doping approaches. Sixty-one scientific reports published between 2015 and 2025 were analyzed, comparing three categories of dopants: (i) metal dopants, (ii) non-metal dopants, and (iii) co-doping systems. In the first section, we discuss fundamental concepts of photocatalysis and recent advances in doping strategies and surface modifications aimed at enhancing the photocatalytic performance of TiO₂. In the second section, we present a comparative analysis based on 61 scientific reports focusing on TiO₂ doping and co-doping processes. Finally, this study summarizes the different categories of doped TiO₂ photocatalysts by comparing the photocatalytic performance employing an alternative performance metric. Full article

Peroxydisulfate (PDS, S₂O₈²⁻) is an important oxidant for a wide range of industrial applications, including organic synthesis, polymer preparation, wastewater treatment and environmental remediation. Currently, PDS is commercially produced by electrolysis of sulfate solution. Photoelectrochemistry (PEC) provides an alternative approach to PDS generation by reducing the energy required to drive this process. Because PEC uses solar light as an abundant, free resource, it is an attractive technique for PDS generation compared to electrolysis. WO₃, owing to its excellent stability in acidic environments, is an excellent metal oxide candidate for producing PDS. Withstanding stronger acidic pH as well as absorption of visible light as a major fraction of solar light renders WO₃ a promising material for PEC-based PDS production when compared with other semiconductors. This mini review examines light-assisted, sustainable production of PDS on WO₃ photoanodes. It mainly involves the oxidation of the anion bisulfate, HSO⁴⁻, in a highly acidic pH. The efficiency of photoelectrochemical generation of PDS is greatly influenced by important factors, including suppressing recombination of photoinduced charge carriers, cocatalyst loading, minimizing competing side reactions, and establishing coupled reactions. In this review, we briefly discussed the key highlights to date in the application of WO₃ as a stable photoanode material for producing PDS. It provides insight into the potential of photocatalysis as an emerging route for the sustainable synthesis of PDS as a valuable chemical oxidant. Besides the significant progress made so far, the PDS production rate remains low, and minimizing the recombination tendency to achieve a higher photocurrent density could further boost PEC-based PDS production. Full article

Benzothiophene polymers, as a class of novel organic semiconductor materials, exhibit significant potential in the field of photocatalysis due to their broad light-responsive range and tunable energy level structures. In this study, a benzothiophene-based polymer organic semiconductor (denoted as P42) was integrated with titanium dioxide (TiO₂) via a simple sol–gel method, yielding an organic–inorganic hybrid material. This composite facilitates the modulation of energy level potentials and promotes the effective separation of photogenerated charges, thereby demonstrating remarkable synergistic catalytic performance in the photocatalytic oxidative coupling of benzylamines. By optimizing the ratio of organic to inorganic components and various photocatalytic reaction conditions, the hybrid material 1.7%P42-TiO₂, containing 1.7 wt% of the dithiophene polymer without any metal cocatalysts, exhibited outstanding performance under an air atmosphere and visible light irradiation after 12 h. It achieved a yield of over 88.7% and a selectivity exceeding 89.8% in the synthesis of N-benzoylaniline, significantly surpassing the performance of pure TiO₂ (52.9% yield, 54.9% selectivity) and P42 (54.4% yield, 54.9% selectivity). Structural and photophysical characterizations, including UV–Vis DRS, XRD, SEM, TEM, and EPR, reveal that the enhanced photocatalytic activity originates from broad visible-light absorption, improved charge separation, and well-matched energy levels. Mechanistic investigations suggest a synergistic pathway involving photoinduced hole oxidation and radical-mediated coupling. This work provides valuable insights and a reference for the solar-driven photocatalytic synthesis of nitrogen-containing platform molecules under mild conditions. Full article

To overcome the limitations imposed by the intermittent nature of sunlight in photocatalytic applications, this research constructs a round-the-clock purification system. We integrated an optimized S-scheme CoFe₂O₄/BiVO₄ (CFO/BV) heterojunction (synthesized via ultrasonic self-assembly at a 0.5:0.5 ratio) with a thermal energy storage (TES) unit consisting of SiO₂-encapsulated Na₂SO₄·10H₂O phase change materials (PCMs). Comprehensive characterization techniques, including XRD, HRTEM, UV-Vis DRS, EPR, and DSC, confirmed the successful formation of the interface, a broadened visible-light response (λ > 650 nm), efficient radical production, and a high latent heat storage capacity (>200 J/g). Under simulated solar irradiation, the composite exhibited superior performance, degrading 98% of the Rhodamine B within 6 h (k = 0.00994 min⁻¹), significantly surpassing single-component counterparts. More importantly, during the subsequent 12 h dark period, the heat released from the PCM maintained the reaction temperature above 35 °C, driving a 64% degradation efficiency via a thermocatalytic pathway. The system demonstrated robust stability (>90% efficiency after five cycles), excellent magnetic recoverability (98%), and high tolerance to saline textile wastewater (<10% activity loss). Furthermore, Life Cycle Assessment (LCA) indicated a 40% reduction in energy consumption compared to conventional UV/TiO₂ processes, highlighting a sustainable strategy for continuous wastewater remediation through synergistic photocatalysis and thermocatalysis. Full article