Search Results (69)

Environmental contamination by persistent industrial dyes such as Amido Black demands highly efficient photocatalysts for advanced water treatment. Structural, chemical, and optical strategies based on TiO₂ nanotube engineering are widely explored for this purpose. In this work, highly ordered TiO₂ nanotube arrays were fabricated by electrochemical anodization and subsequently decorated with Pd nanoparticles via potentiostatic electrodeposition (10–300 s), enabling precise control of Pd nanoparticle size and loading. The resulting materials were systematically characterized by SEM, TEM, XRD, XPS, UV–vis DRS, and PL spectroscopy, and their properties were correlated with the photocatalytic degradation of Amido Black under both UV and visible light irradiation. The study reveals a clear size-dependent duality in the role of Pd. For intermediate Pd nanoparticles (≈9 nm, 20 s), Pd behaves predominantly as an electron sink, forming an efficient Schottky junction with anatase TiO₂ that markedly suppresses charge carrier recombination. This configuration yields ≈ 97% Amido Black removal after 120 min of UV irradiation, with an apparent rate constant about three times higher than that of bare TiO₂ nanotubes. In contrast, for ultra-small Pd nanoparticles (≈6 nm, 10 s), interfacial defect states sensitize TiO₂ to visible light, enabling ≈ 65% degradation after 270 min and a rate constant roughly four times higher than that of undecorated nanotubes under visible illumination. At long deposition times (≥150 s), Pd agglomeration leads to enhanced photoluminescence and markedly reduced photocatalytic activity, indicating increased recombination and less effective utilization of photogenerated charges. This provides a practical design rule to rationally tailor Pd–TiO₂ nanotube photocatalysts for targeted UV or visible light applications in dye removal and broader environmental remediation scenarios Full article

TiO₂ nanoparticles were synthesized by a simple sol–gel route followed by high-temperature calcination at 800 °C, aiming to obtain an anatase-dominant reference photocatalyst with enhanced structural stability after severe thermal treatment. Raman spectroscopy and X-ray diffraction confirmed that anatase is the major crystalline phase, with only a minor rutile contribution after calcination at 800 °C. Nitrogen adsorption–desorption measurements revealed a narrow mesoporous contribution arising from interparticle voids and a relatively high specific surface area (108 m² g⁻¹) despite the severe thermal treatment, while electron microscopy showed nanometric primary particles assembled into compact agglomerates. Surface hydroxyl groups were identified by Fourier-transform infrared spectroscopy, consistent with sol–gel-derived TiO₂ systems. Diffuse reflectance UV–Vis spectroscopy combined with Kubelka–Munk and Tauc analysis yielded an optical band gap of 3.12 eV, typical of anatase TiO₂. Methylene blue (MB) was used as a probe molecule to evaluate photocatalytic activity under ultraviolet and visible light irradiation. Under UV illumination, degradation kinetics were governed by band-gap excitation and reactive oxygen species generation, whereas a slower but reproducible reference behavior under visible light was predominantly associated with surface-related effects and dye sensitization rather than intrinsic visible-light absorption. Overall, the results establish this anatase-dominant TiO₂ as a reliable high-temperature reference photocatalyst, retaining measurable activity after calcination at 800 °C and exhibiting UV-driven behavior as the dominant contribution. Full article

Titanium dioxide (TiO₂) is a widely used photocatalyst, yet its activity is limited to ultraviolet light due to its large band gap. To extend absorption into the visible spectrum, this study developed a dual-sensitizer strategy by coupling perylene tetracarboxylic acid (PTCA) and copper phthalocyanine tetracarboxylic acid (CuPcTC) onto TiO₂. Both dyes were selected for their strong visible light absorption, photostability, and efficient charge transfer properties. Hybrid photocatalysts were prepared via an ultrasonication–coprecipitation method and incorporated into coatings. Optical, morpho-structural, thermal, and electrochemical methods were used to characterize the hybrid photocatalysts, while photocatalytic performances were evaluated by UV–Vis spectroscopy, hydroxyl radical generation, and Methylene Blue degradation under simulated solar light. The dual-sensitized TiO₂ composites exhibited broadened absorption across 400–750 nm, effective charge separation, and stable radical generation. Among the tested samples, the PTCA–CuPcTC hybrid (P3) demonstrated the highest activity, achieving efficient degradation of Methylene Blue with sustained performance over repeated cycles. Characterization confirmed uniform distribution of sensitizers, high crystallinity, and adequate thermal stability. These findings indicate that combining PTCA and CuPcTC provides synergistic benefits in light harvesting, charge transfer, and durability. The dual-sensitizer approach offers a promising route for visible-light-responsive photocatalysts in environmental remediation. Full article

The wastewater discharged from the aquaculture and textile industries often contains toxic organic dyes, such as methylene blue (MB) and malachite green (MG), which pose significant risk to public health and ecosystem stability due to their high chemical stability, bioaccumulation potential and resistance to degradation. To address these challenges, the development of an integrated system capable of both efficient degradation and highly sensitive detection of organic dyes is essential for ecological restoration and early pollution monitoring. Herein, bifunctional Fe₃O₄-Cu₂O-Ag-GO (FCA 2-GO) nanocomposites (NCs) were developed by depositing Cu₂O, Ag nanocrystals and graphene oxide (GO) onto the surfaces of Fe₃O₄ nanocrystals. This multifunctional material acted as both a photocatalyst and a surface-enhanced Raman scattering (SERS) platform, enabling simultaneous degradation and ultrasensitive detection of organic dyes. Under simulated sunlight irradiation, FCA 2-GO NCs achieved over 98% degradation of both MB and MG within 60 min, driven by the synergistic action of reactive oxygen species (·O₂⁻ and ·OH). The degradation kinetics followed pseudo-first-order behavior, with rate constants of 0.0381 min⁻¹ (MB) and 0.0310 min⁻¹ (MG). Additionally, the FCA 2-GO NCs exhibited exceptional SERS performance, achieving detection limits as low as 10⁻¹² M for both dyes, attributed to electromagnetic–chemical dual-enhancement mechanisms. Practical applicability was demonstrated in soil matrices, showcasing robust linear correlations (R² > 0.95) between SERS signal intensity and dye concentration. This work provides a dual-functional platform that combines efficient environmental remediation with trace-level pollutant monitoring, offering a promising strategy for sustainable wastewater treatment and environmental safety. Full article

Graphitic carbon nitride (g-C₃N₄) is emerging as one of the most promising non-metallic semiconductors for the degradation of pollutants in water by photocatalytic processes. Its exceptional reduction–oxidation (redox) potentials and adequate band gap of approximately 2.7 eV give it the ability to absorb in the visible light range. However, the characteristic sensitivity to light absorption is limited, leading to rapid recombination of electron–hole pairs. Therefore, different strategies have been explored to optimize this charge separation, among which the formation of heterostructures based on g-C₃N₄ is highlighted. This review addresses recent advances in photocatalysis mediated by g-C₃N₄ heterostructures, considering the synthesis methods enabling the optimization of the morphology and active interface of these materials. Next, the mechanisms of charge transfer are discussed in detail, with special emphasis on type II, type S, and type Z classifications and their influence on the efficiency of photodegradation. Subsequently, the progress in the application of these photocatalysts for the degradation of water pollutants, such as toxic organic dyes, pharmaceutical pollutants, pesticides, and per- and polyfluoroalkyl substances (PFAS), are analyzed, highlighting both experimental advances and remaining challenges. Finally, future perspectives oriented towards the optimization of heterostructures, the efficiency of synthesis methods, and the practical application of these in photocatalytic processes for environmental remediation. Full article

Titanium dioxide (TiO₂) is a wide-bandgap semiconductor material with broad application potential, known for its excellent photocatalytic performance, high chemical stability, low cost, and non-toxicity. These properties make it highly attractive for applications in photovoltaic energy, environmental remediation, and optoelectronic devices. For instance, TiO₂ is widely used as a photocatalyst for hydrogen production via water splitting and for degrading organic pollutants, thanks to its efficient photo-generated electron–hole separation. Additionally, TiO₂ exhibits remarkable performance in dye-sensitized solar cells and photodetectors, providing critical support for advancements in green energy and photoelectric conversion technologies. Boron-doped diamond (BDD) is renowned for its exceptional electrical conductivity, high hardness, wide electrochemical window, and outstanding chemical inertness. These unique characteristics enable its extensive use in fields such as electrochemical analysis, electrocatalysis, sensors, and biomedicine. For example, BDD electrodes exhibit high sensitivity and stability in detecting trace chemicals and pollutants, while also demonstrating excellent performance in electrocatalytic water splitting and industrial wastewater treatment. Its chemical stability and biocompatibility make it an ideal material for biosensors and implantable devices. Research indicates that the combination of TiO₂ nanostructures and BDD into heterostructures can exhibit unexpected optical and electrical performance and transport behavior, opening up new possibilities for photoluminescence and rectifier diode devices. However, applications based on this heterostructure still face challenges, particularly in terms of photodetector, photoelectric emitter, optical modulator, and optical fiber devices under high-temperature conditions. This article explores the potential and prospects of their combined heterostructures in the field of optoelectronic devices such as photodetector, light emitting diode (LED), memory, field effect transistor (FET) and sensing. TiO₂/BDD heterojunction can enhance photoresponsivity and extend the spectral detection range which enables stability in high-temperature and harsh environments due to BDD’s thermal conductivity. This article proposes future research directions and prospects to facilitate the development of TiO₂ nanostructured materials and BDD-based heterostructures, providing a foundation for enhancing photoresponsivity and extending the spectral detection range enables stability in high-temperature and high-frequency optoelectronic devices field. Further research and exploration of optoelectronic devices based on TiO₂-BDD heterostructures hold significant importance, offering new breakthroughs and innovations for the future development of optoelectronic technology. Full article

Visible-light-responsive silver-phosphate-sensitized fly-ash particles loaded on polyurethane nanofiber (Ag₃PO₄–FA/PU NFs) membrane photocatalysts were prepared by electrospinning followed by an ion-exchange method and characterized with state-of-art techniques. With the assistance of Ag₃PO₄–FA/PU NFs, 98 % of methylene blue (MB) was degraded within 60 min. The combination of FA and Ag₃PO₄ particles provided simultaneous adsorption and degradation of MB in an aqueous solution, resulting in the fast removal of the dye. Also, the Ag₃PO₄–FA/PU NFs exhibited excellent antibacterial performance toward Escherichia coli and Staphylococcus aureus bacteria. Thus, the prepared photocatalyst may provide a potential outcome for environmental remediation, especially wastewater treatment applications. Full article

With unique photochemical properties, graphitic carbon nitride (g-C₃N₄) has gained significant attention for application in photocatalytic degradation of a wide range of organic pollutants. However, its performance is limited by the rapid electron–hole recombination and the relatively weak redox capability. Substantial progress has been made in the preparation of g-C₃N₄-based photocatalysts with enhanced photocatalytic activity. This review summarizes the recent advances in strategies to improve the photocatalytic activity of g-C₃N₄-based photocatalysts and their application in the photocatalytic degradation of organic pollutants. Morphology control, doping, functionalization, metal deposition, dye sensitization, defect engineering, and construction of heterojunctions can be used to improve the photocatalytic activity of g-C₃N₄ through promoting charge carrier separation, reducing the bandgap, and suppressing charge recombination. Furthermore, a range of oxidants, such as hydrogen peroxide and persulfate, can be coupled with g-C₃N₄-based photocatalysts to enhance the generation of reactive oxygen species and boost the photocatalytic degradation of organic pollutants. Precise control over the g-C₃N₄ structure during the synthesis process remains a challenge, and further improvements are required in photocatalyst stability and the mineralization rates of organic pollutants. More research and development effort is needed to address the existing challenges, refine the design of g-C₃N₄-based photocatalysts to improve their activity, and promote their practical application in pollutant degradation. Full article

Zinc oxide (ZnO) photocatalysts have emerged as a promising material for environmental and energy applications due to their exceptional photocatalytic properties. Initially recognized for their efficiency under ultraviolet (UV) light, recent advancements have focused on enhancing ZnO’s visible light activity (VLA) to address its inherent limitations. This review provides an overview of ZnO’s structure, electronic properties, and photocatalytic mechanisms. Various strategies for modifying ZnO to harness visible light, including metal and non-metal doping, dye sensitization, and semiconductor coupling, are discussed. Special emphasis is placed on the mechanisms behind visible light absorption and reactive oxygen species (ROS) generation, as deduced through physicochemical and photoelectrochemical analyses. The applications of ZnO in environmental remediation are comprehensively explored, particularly for water treatment, disinfection, and air purification. The photocatalytic degradation of pollutants, including persistent organic compounds, pharmaceuticals, dyes, and pesticides, using ZnO is reviewed and compared with conventional UV-activated ZnO materials. This review underscores the potential of ZnO as an efficient and sustainable solution for environmental purification. Full article

The textile industry is a major contributor to environmental pollution, primarily through the discharge of wastewater loaded with dyes and contaminants that disrupt natural ecosystems. This study aims to develop a hybrid material by functionalizing carbon nanodots (CNDs) with the donor-π-acceptor organic dye L1 via amide coupling. By chemically modifying the surface of CNDs, we can enhance their multifunctionality and tailor their molecular composition. This innovative approach seeks to replace expensive dyes with cost-effective CNDs synthesized from citric acid and ethylenediamine using a domestic microwave oven, potentially improving the stability of the resulting hybrid. Additionally, TiO₂ anatase particles were synthesized as a metal oxide platform and sensitized with both pristine materials and the CND-L1 hybrid. A range of physicochemical methods was employed to analyze the elemental, structural, and optical properties of these materials. In photocatalytic degradation tests of methyl orange, the sensitized catalysts demonstrated significantly improved efficiency compared to TiO₂ alone. While CNDs exhibited good stability and enhanced L1’s stability, scavenger experiments revealed that holes and hydroxyl radicals play crucial roles in the degradation mechanism. This research underscores the promise of CND hybrids in advancing pollutant degradation technologies while reducing reliance on costly photocatalysts. Full article

Based on the photocatalytic activity and magnetic nature of magnetite and goethite, as well as the oxygen storage characteristic of cerianite, a magnetic ternary hybrid composite including cubic CeO₂, cubic Fe₃O₄ and orthorhombic FeOOH, designated as Fe₃O₄/FeOOH/CeO₂, was successfully synthesized with different Ce:Fe molar ratios using a simple hydrothermal route without subsequent calcination process, and employed as photocatalysts for the degradation of Acid Orange 7 (AO7) dye. The absorption range of light by the Fe₃O₄/FeOOH/CeO₂ composites was broadened, and the intensity was enhanced. Furthermore, there existed a possibility of hybridization and doping among the three crystalline structures, with the elements Ce, Fe and O exhibiting a uniform distribution, significantly enhancing the photocatalytic efficiency of the Fe₃O₄/FeOOH/CeO₂ composites in promoting the photodegradation of AO7. The magnetic response behaviors of hybrid composites synthesized with different Ce:Fe molar ratios were investigated. The adsorptive degradation of AO7 in darkness and the photocatalytic degradation of AO7 under UV light illumination were evaluated. Moreover, ten cycling runs of the photocatalytic degradation of AO7 under simulated UV illumination of Fe₃O₄/FeOOH/CeO₂ synthesized with a Ce:Fe molar ratio of 1:15 were performed. The hybrid ternary composites were proved to have excellent magnetic sensitivity, exhibited outstanding photocatalytic activities and demonstrated remarkable stability. It is anticipated that magnetic Fe₃O₄/FeOOH/CeO₂ ternary hybrid composites may have potential applications in the treatment of organic dye sewage. Full article

The photocatalytic decomposition of ammonia to produce N₂ and H₂ was achieved using single-walled carbon nanotube (SWCNT) nanohybrids. The physical modification of ferrocene-dye-encapsulated CNTs by amphiphilic C₆₀-dendron yielded nanohybrids with a dye/CNT/C₆₀ coaxial heterojunction. Upon irradiation with visible light, an aqueous solution of NH₃ and dye@CNT/C₆₀-dendron nanohybrids produced both N₂ and H₂ in a stoichiometric ratio of 1/3. The action spectra of this reaction clearly demonstrated that the encapsulated dye acted as the photosensitizer, exhibiting an apparent quantum yield (AQY) of 0.22% at 510 nm (the λ_max of the dye). This study reports the first example of dye-sensitized ammonia decomposition and provides a new avenue for developing efficient and sustainable photocatalytic hydrogen production systems. Full article

The rapid expansion of industrial activities has resulted in severe environmental pollution manifested by organic dyes discharged from the food, textile, and leather industries, as well as hazardous gas emissions from various industrial processes. Titanium dioxide (TiO₂)-nanostructured materials have emerged as promising candidates for effective photocatalytic dye degradation and gas sensing applications owing to their unique physicochemical properties. This study investigates the development of a photocatalyst and a liquefied petroleum gas (LPG) sensor using hydrothermally synthesized globosa-like TiO₂ nanostructures (GTNs). The synthesized GTNs are then evaluated to photocatalytically degrade methylene blue dye, resulting in an outstanding photocatalytic activity of 91% degradation within 160 min under UV light irradiation. Furthermore, these nanostructures are utilized to sense liquefied petroleum gas, which attains a superior sensitivity of 7.3% with high response and recovery times and good reproducibility. This facile and cost-effective hydrothermal method of fabricating TiO₂ nanostructures opens a new avenue in photocatalytic dye degradation and gas sensing applications. Full article

Photocatalysis, mainly using TiO₂ as a catalyst, has emerged as a promising method to address the issue of wastewater treatment. This study explores the enhanced photocatalytic activity of TiO₂ through the introduction of reduced graphene oxide (rGO) and cadmium sulfide (CdS) as selective metal dopants. The incorporation of rGO and CdS into the TiO₂ lattice aims to optimize its photocatalytic properties, including bandgap engineering, charge carrier separation, and surface reactivity. The unique combination of CdS and rGO with TiO₂ is expected to boost degradation efficiency and reduce the reliance on expensive and potentially harmful sensitizers. This experimental investigation involves the synthesis and characterization of TiO₂-based photocatalysts. The photocatalytic degradation of methyl orange (MO) and methylene blue (MB) was assessed under controlled laboratory conditions, studying the influence of metal dopants on degradation kinetics and degradation efficiency. Furthermore, the synthesized photocatalyst is characterized by advanced techniques, including BET, SEM, TEM, XRD, and XPS analyses. The degraded samples were analyzed by UV-Vis spectroscopy. Insights into the photoexcitation and charge transfer processes shed light on the role of metal dopants in enhancing photocatalytic performance. The results demonstrate the potential of a TiO₂-rGO-CdS-based photocatalyst in which 100% degradation was achieved within four hours for MO and six hours for MB, confirming efficient azo dye degradation. The findings contribute to understanding the fundamental principles underlying the photocatalytic process and provide valuable guidance for designing and optimizing advanced photocatalytic systems. Ultimately, this research contributes to the development of sustainable and effective technologies for removing azo dyes from various wastewaters, promoting environmental preservation and human well-being. Full article

In this study, two distinct photocatalysts, namely tin(IV)porphyrin-sensitized titanium dioxide nanotubes (SnP-TNTs) and titanium dioxide nanofibers (TNFs), were synthesized and characterized using various spectroscopic techniques. SnP-TNTs were formed through the hydrothermal reaction of NaOH with TiO₂ (P-25) nanospheres in the presence of Sn(IV)porphyrin (SnP), resulting in a transformation into Sn(IV)porphyrin-imbedded nanotubes. In contrast, under similar reaction conditions but in the absence of SnP, TiO₂ (P-25) nanospheres evolved into nanofibers (TNFs). Comparative analysis revealed that SnP-TNTs exhibited a remarkable enhancement in the visible light photodegradation of model pollutants compared to SnP, TiO₂ (P-25), or TNFs. The superior photodegradation activity of SnP-TNTs was primarily attributed to synergistic effects between TiO₂ (P-25) and SnP, leading to altered conformational frameworks, increased surface area, enhanced thermo-chemical stability, unique morphology, and outstanding visible light photodegradation of cationic methylene blue dye (MB dye). With a rapid removal rate of 95% within 100 min (rate constant = 0.0277 min⁻¹), SnP-TNTs demonstrated excellent dye degradation capacity, high reusability, and low catalyst loading, positioning them as more efficient than conventional catalysts. This report introduces a novel direction for porphyrin-incorporated catalytic systems, holding significance for future applications in environmental remediation. Full article