Search Results (4,389)

Using bismuth oxide (Bi₂O₃) as the matrix and employing a doping modification strategy to introduce the rare-earth element La, this study prepared La/Bi₂O₃ visible-light-responsive photocatalysts with different doping ratios. The research systematically investigated the regulation mechanisms of La doping on the material’s phase structure, microstructure, band structure characteristics, and visible-light photocatalytic performance. The results indicate that an appropriate amount of La³⁺ equivalently substitutes Bi³⁺ in the lattice, inducing the complete transformation of pure α-Bi₂O₃ into the tetragonal β-Bi₂O₃ phase while maintaining the integrity of the crystal framework. Meanwhile, the modulation of the local electronic structure caused by La³⁺ substitution effectively narrows the bandgap width and broadens the visible-light response range; it also acts as an electron trap to significantly suppress the recombination of photo-generated electron–hole pairs, thereby enhancing charge transport efficiency. Visible-light catalytic degradation experiments confirmed that 4% La/Bi₂O₃ exhibits the optimal degradation kinetics for RhB, achieving a 72.88% degradation rate of Rhodamine B within 60 min of visible-light irradiation. The first-order reaction rate constant was 23 times that of pure Bi₂O₃, and the material demonstrated good stability under repeated cycles. Radical trapping experiments indicated that the order of contribution of active species was ·O₂⁻ > h⁺ > ·OH, with the superoxide radical (·O₂⁻) being the dominant active species. This study confirms that appropriate lattice doping with La can synergistically optimize the structure and optoelectronic properties of Bi₂O₃, providing experimental evidence and theoretical references for the rational design of highly efficient and stable visible-light-responsive Bi₂O₃-based photocatalytic materials. Full article

Strict monitoring of methane (CH₄) during underground coal mining is necessary, as the lower explosive limit (LEL) is 5 vol% in air. A conventional tin oxide (SnO₂)-based metal–oxide semiconductor (MOS) sensor has an operating temperature of 200–400 °C, which requires a prohibitive power demand and entails the risk of ignition within an intrinsically safe environment. The decoration of SnO₂ nanoarchitectures with palladium has been demonstrated to achieve room temperature (RT) detection of CH₄ due to the chemical sensitisation spillover mechanism and electronic sensitisation by Schottky barrier modulation. Moreover, palladisation of SnO₂ nanowires (NWs) is likely to be an effective route for achieving a more efficient detection of CH₄ aerosol at RT or near RT. The purpose of this mini-review is to provide a critical synthesis of advances that have been reported between 2020 and 2026. Because no published study to date has directly demonstrated room-temperature CH₄ detection using pure Pd-decorated SnO₂ nanowires, performance data from mechanistically analogous systems—namely H₂-sensing Pd–SnO₂ nanowires and CH₄-sensing non-nanowire Pd–SnO₂ nanostructures—are included in this review and are explicitly labelled as such throughout. This absence of direct RT CH₄ NW data constitutes the primary research gap motivating this review. The performance of Pd-containing SnO₂ nanostructures reported in the literature spans response values of 17.6 (300 ppm CH₄, 2.5 mol% Pd–SnO₂ nanoporous, 340 °C) to 21.3 (3000 ppm CH₄, bimetallic Pt–Pd–SnO₂ mesoporous, 400 °C), representing a 3–10× improvement over bare SnO₂ (response: 2–10 in the same concentration range). These benchmarks were obtained at elevated temperatures (340–400 °C); no equivalent room-temperature CH₄ detection data for Pd–SnO₂ nanowires currently exists in the published literature. Reported response times range from 3 to 9 s at elevated temperature (340–400 °C) to 74–78 s for room-temperature visible-light-activated systems, where photocatalytic oxygen activation is the rate-limiting step. The 30 s MSHA alarm threshold is met by elevated-temperature systems but remains a challenge for RT configurations. The LODs were 175.9 ppb (bimetallic PdxPt/SnO₂ mesoporous system). Two hybrid composites containing rGO exhibited an extended capability for RT operation. Bimetallic PdPt decoration and ML-augmented sensor arrays are identified as the most promising near-term pathways to bridge the selectivity and stability gaps for certified mining deployment. Full article

The persistence of antibiotics like ciprofloxacin (CIP) in aquatic environments necessitates the development of efficient, low-cost wastewater treatment technologies. This study investigates a low-temperature fabrication strategy for mixed-phase copper oxide (CuO/Cu₂O) coatings synthesized via co-precipitation and immobilized using electrophoretic deposition (EPD). A critical finding was that a 25 min precursor aging time (T25) preserved a metastable mixture of CuO and Cu₂O phases, which is highly advantageous for creating heterojunction interfaces that enhance charge separation. In contrast, extended aging (T35) promoted phase consolidation toward bulk CuO, reducing catalytic surface area. During the EPD process, applied voltage acted as an influence to the relative phase composition and deposition behavior of the deposited coatings; 1.0 V was identified as the optimal condition, balancing high phase fidelity with enhanced crystallinity (average crystallite size of 30.6 nm) and mechanical stability. Photocatalytic experiments demonstrated significant CIP degradation, with the 0.9 V and 1.0 V films outperforming the 1.2 V film, possibly due to more favorable surface chemistry and phase diversity. While the 0.9 V film achieved the highest mineralization efficiency (18% TOC removal), the 1.0 V film offered the best balance between photocatalytic activity, structural stability, and phase selectivity for practical applications. High-Performance Liquid Chromatography-Mass Spectrometry HPLC-MS analysis suggested that degradation proceeds through oxidative pathways involving piperazine ring cleavage and defluorination. Full article

Photocatalytic degradation technology has been widely acknowledged for its low cost and high degradation efficiency. However, the loss, migration and difficult recovery of powdered catalysts are still critical bottlenecks for practical applications. In this study, silver nanoparticles (Ag NPs)/polyvinylidene fluoride (PVDF) photocatalytic composite membranes were in situ fabricated by incorporating AgNO₃ into a PVDF casting solution, followed by electrospinning and UV post-treatment. The resulting membranes exhibited sustained photocatalytic capability towards dyes and antibiotics. The optimal membrane achieved 89.6% and 83.0% degradation efficiency for chloramphenicol (CAP) and rhodamine B within 16 h under UV irradiation, respectively. Free radical trapping experiments revealed that the superoxide radical (·O₂⁻) dominated the photocatalytic degradation of CAP, and the mechanism of photocatalytic degradation was explored. Additionally, the Ag NPs/PVDF photocatalytic membrane demonstrated a distinct antibacterial efficacy against Staphylococcus aureus (S. aureus) with a distinct inhibition zone of 20 mm, effectively inhibiting bacterial proliferation. Full article

The immobilization of photocatalysts onto biodegradable polymeric supports has emerged as an effective strategy to overcome catalyst recovery limitations associated with conventional slurry photocatalytic systems. In this study, chitosan/TiO₂ composite beads with different chitosan properties and TiO₂ loadings were synthesized and evaluated for the photocatalytic removal of Reactive Black 5 (RB5), a recalcitrant azo dye commonly encountered in textile wastewater. The effects of chitosan molecular weight, degree of deacetylation, and crosslinking treatment on the structural characteristics and photocatalytic performance of the composite beads were systematically investigated. The synthesized composites were characterized through physical property measurements, point of zero charge (pH_pzc) determination, and FTIR analyses. Photocatalytic performance was evaluated under various operational conditions, including pH, catalyst dosage, initial dye concentration, and temperature. Among the prepared materials, the crosslinked chitosan/TiO₂ composite bead produced from chitosan with an 85% degree of deacetylation exhibited the highest mineralization efficiency, achieving 76.23% total organic carbon (TOC) removal. FTIR analyses performed before and after treatment indicated that RB5 removal occurred through the combined effects of adsorption and photocatalytic oxidation. The effects of operational parameters revealed that acidic conditions significantly enhanced RB5 removal, while increasing temperature improved reaction kinetics and overall degradation efficiency. Kinetic studies indicated that the photocatalytic degradation process was best described by the pseudo-first-order kinetic model, with correlation coefficients ranging from 0.9841 to 0.9976. Arrhenius analysis yielded an apparent activation energy of 11.76 kJ mol⁻¹, indicating a low energy barrier for the degradation process. The results demonstrate that crosslinked chitosan/TiO₂ composite beads are promising, environmentally friendly, and sustainable photocatalytic materials for the treatment of dye-containing wastewater and advanced water purification applications. Full article

SrTiO₃/Nb₂O₅ composite materials with 1 and 10 wt.% Nb₂O₅ were prepared by a sol–gel route and characterized by XRD, Raman spectroscopy, SEM, BET, UV-Vis DRS, photoluminescence, and dielectric spectroscopy. The photocatalytic activity was evaluated via degradation of rhodamine B and tetracycline under UV and visible light. The addition of Nb₂O₅ resulted in a significant reduction in specific surface area (from 22.7 to 3.1 m²/g), a narrowing of the optical band gap (from 3.22 to 2.49 eV), and a decrease in photoluminescence intensity. Despite these changes, the photocatalytic performance decreased with increasing Nb₂O₅ content. For rhodamine B degradation, the UV rate constant fell from 0.0136 min⁻¹ for pristine SrTiO₃ to 0.0035 min⁻¹ for SrTiO₃/10% Nb₂O₅. The lower activity is mainly ascribed to the loss of active sites, surface carbonate formation, and enhanced non-radiative recombination at interface defects, which suppress charge transfer to the surface. The results demonstrate that careful control of the composite microstructure is essential for achieving efficient photocatalysis, even when heterojunction formation is thermodynamically favorable. Full article

Photocatalytic antibacterial coatings have emerged as a promising antibiotic-free strategy for combating healthcare-associated infections, biofilm formation, marine biofouling, and environmental microbial contamination. Unlike conventional antimicrobial approaches, photocatalytic systems continuously generate reactive oxygen species (ROS) under light irradiation, enabling broad-spectrum antimicrobial activity while minimizing the risk of antimicrobial resistance. This review systematically summarizes the fundamental mechanisms underlying photocatalytic antibacterial activity, including photogenerated charge-carrier dynamics, ROS generation pathways, and microbial inactivation processes. We further highlight recent advances in photocatalyst design, spanning conventional semiconductor photocatalysts, heterojunction engineering, cocatalyst modification, and two-dimensional material-assisted strategies for enhanced photocatalytic performance. Crucially, particular emphasis is placed on coating architectures and interfacial regulation, including encompassing fabrication methodologies, coating–substrate adhesion, internal heterointerface design, and coating–microorganism interactions, which dictate long-term durability and antibacterial efficacy. Finally, we explore the diverse applications of these coatings in medical devices, environmental remediation, and marine antifouling, while identifying current bottlenecks and future research trajectories toward developing durable, highly efficient, and clinically translatable antimicrobial surface technologies. Full article

The coordination chemistry of “salen-type” Schiff bases with the uranyl ion, trans-{U^VIO₂}²⁺, attracts the interest of several inorganic chemistry groups worldwide for a variety of reasons. The full synthetic investigation of the {UO₂}²⁺/H₂L reaction system, where H₂L is bis(2-hydroxyacetophenone)ethylenediamine, has provided access to complexes [UO₂(L)(EtOH)] (1) and [UO₂(L)(DMF)] (2) in moderate to good yields. The molecular structures of the two complexes are similar. The U^VI atoms are bonded to five oxygen and two nitrogen atoms in a distorted pentagonal bipyramidal geometry. The two uranyl oxo(or oxido) atoms occupy the axial positions, and the {O=U=O}²⁺ moiety is almost linear. The equatorial donor atoms are the two oxygens and the two nitrogens from the tetradentate chelating (1.1111 using Harris notation) L²⁻ ligand, and the oxygen atom of the coordinated solvent molecule. H-bonded dimers of 1 exist in its crystal structure. The complexes were fully studied in the solid state by IR, Raman, UV/Vis (diffuse reflectance) and emission spectroscopies, and the data are discussed in terms of the known structural data of the complexes and the coordination modes of the ligands. The structures of the complexes persist in solution as evidenced by NMR (¹H, ¹³C{¹H}) and UV/Vis spectroscopies, as well as by molar conductivity data. Complexes 1 and 2 exhibit moderate photocatalytic activity towards the degradation of the model organic dye methylene blue under continuous UV irradiation in aqueous media. The reaction kinetics were fitted using the Langmuir-Hinshelwood pseudo-first-order model. Combined IR and powder X-ray diffraction data show that the photocatalyst 1 remains unchanged after the photocatalytic experiment, whereas 2 undergoes DMF leaching. Based on literature reports, a simplified single-electron transfer mechanism has been proposed for the photocatalytic activity. Full article

Photocatalytic fuel cells (PFCs) integrate photocatalysis with fuel cell technology to enable simultaneous wastewater treatment and energy recovery. This review examines recent advances in PFC cathode materials, focusing on design strategies, reduction mechanisms, and applications. The cathode governs electron transfer and interfacial reactions, including oxygen reduction (4e⁻ or 2e⁻ pathways), direct pollutant electroreduction, and oxidant activation for radical generation. Cathodic materials including transition metal oxides/sulfides, carbon-based materials, metal–organic frameworks and their derivatives, are systematically summarized, evaluating their respective activities, stabilities and costs. Rational design via heterojunction engineering, defect modulation, and composite construction enables tunable reaction pathways and enhanced performance. Furthermore, representative applications are reviewed, with particular attention to the effective degradation of organic pollutants, and reduction of heavy metals and radionuclides in PFCs. Future efforts should prioritize long-term stability, scalable fabrication, and multi-functional cathode integration. Full article

The contamination of water bodies with organic pollutants has emerged as one of the most pressing environmental and public health challenges of the modern era. The continuous discharge of dyes, pesticides, agricultural runoff, and pharmaceutical residues into the aquatic ecosystem degrades water quality. Long-term exposure to these organic pollutants poses a severe risk to human and aquatic life. ZnO and TiO₂ have emerged as promising photocatalysts, particularly for degrading organic waste in wastewater. However, their photocatalytic activity is limited to the UV region due to their wide band gaps. To improve nanoparticle efficiency, polydopamine (PDA) is incorporated as a modifying agent. PDA-modified ZnO and TiO₂ nanocomposites exhibit enhanced photocatalytic activity in the degradation of various organic pollutants under visible light, compared with their unmodified counterparts. Furthermore, they exhibit improved antibacterial activity against a variety of waterborne pathogens; this is advantageous as wastewater contains both chemical pollutants and microorganisms. Thus, the combined photocatalytic and antibacterial properties of PDA-modified ZnO and TiO₂ make them promising materials for next-generation wastewater treatment. Full article

While silver halides (AgX) are promising visible-light photocatalysts for water remediation, their practical deployment is severely hindered by intrinsic photocorrosion, rapid charge recombination, and macroscopic recovery challenges. Here, we demonstrate a monolithic AgX/biomass carbon aerogel composite platform, constructed by anchoring AgX nanocrystals in situ onto a 3D hierarchical carbon skeleton. The carbon network not only suppresses nanoparticle aggregation but also plays contrasting optical roles: amplifying the intrinsic visible-light absorption of AgBr while endowing the otherwise UV-confined AgCl with substantial visible-light response. Consequently, the optimal 30 wt% AgBr/CA composite achieves a 95.68% methylene blue degradation efficiency within 60 min—outperforming pristine AgBr by 2.6-fold—while establishing robust activity against two additional, structurally distinct pollutants: rhodamine B and the colorless antibiotic ciprofloxacin. Notably, the free-standing monolith retains exceptional activity over six consecutive cycles. Mechanistic investigations reveal that the carbon aerogel functions as an electron-accepting reservoir, which accelerates interfacial charge separation and steers electron flow toward superoxide radical generation. Notably, XRD and XPS analyses confirm that no detectable metallic Ag⁰ is present in the as-prepared composites. This work establishes a sustainable and scalable architectural paradigm for designing highly efficient, stable, and easily recyclable photocatalytic systems. Full article

In this work, a comprehensive analysis of the relationship between photoluminescent, thermo-oxidative, and photocatalytic (upon simulated sunlight exposure) properties of ZnO powders is performed. The correlation between the X-ray diffraction and microscopic data is studied. ZnO powders of various sizes and morphologies were used: pseudo-spherical nanoparticles (30–50 nm), submicron faceted crystallites (100–500 nm), and plate- and rod-like microstructures (up to 20 μm). The mean specific surface area values were 32 m²/g, 3.8 m²/g, and 2.6 m²/g for pseudo-spherical nanoparticles, submicron faceted crystallites, and plate- and rod-like microstructures, respectively. According to the XRD data, microstresses and carbon-based impurities were present in ZnO nanoparticles, which is characteristic of nanomaterials synthesized at low temperatures. According to the photoluminescence spectroscopy data, the emission in ZnO was reduced due to high defectiveness, and characteristic emission bands indicated the presence of organic impurities. Upon long signal registration times, an intensive luminescence band with an effective maximum at 579 nm occurred, which indicated the presence of long-term components exhibiting decay times τ ~300 μs. According to the XRD data, the crystal structure parameters of ZnO submicro- and microparticles were close, with no impurities present. In their photoluminescence spectra, pronounced UV and defect-related bands were present with intensity ratios of 11.6 and 6.88, respectively. The decrease in the UV and defect-related luminescence band intensity ratios indicates deviation from the stoichiometry toward an increased Zn over oxygen content. At long signal registration times, in submicron ZnO particles, a luminescence band with maxima at 425 and 490 nm is present, which decays rapidly. An emission band in the 530 nm region is also present, which decays for ≤80 μs, and a weak long-wavelength emission decaying for ~100 μs. At long delay and strobe times (up to milliseconds), only an emission in the 460 nm region is observed, which we connect to the triplet–singlet transition of a defect center (F*, F⁺*). At lower intensities, an emission connected to the surface contamination by organic impurities is observed. In photoluminescence spectra of ZnO microparticles, no long-wavelength emission components are observed. However, upon immersing into methylene blue solution, a modification of the surface and UV region of the spectra is observed with signs of charge carrier recombination rate acceleration. It is shown that the catalytic action of ZnO powders in polyethylene thermo-oxidation processes is determined by a combination of factors. In addition to dispersity and concentration, which are the key parameters, the morphology of ZnO particles, the presence of impurities, the surface state, and the distribution of active sites have a significant influence on catalysis. It has been experimentally demonstrated that these secondary factors can markedly affect the rate of radical formation in polyethylene films and alter their resistance to oxidation. ZnO nanoparticles exhibited low catalytic activity in both photocatalysis (rate constant 0.146 min⁻¹) and thermocatalysis due to the high defect density of the crystallites and the presence of carbon-containing impurities. Submicron ZnO particles, owing to a high carrier generation rate and suppressed recombination (via trapping), demonstrated the highest photoactivity (rate constant 0.729 min⁻¹). Submicron ZnO particles exhibit a catalytic effect on the thermo-oxidation of polyethylene (PE films); however, at concentrations above 8 wt.% a transition to an inhibiting effect is observed. ZnO microparticles catalyzed the oxidation of PE films over a broader concentration range (1–12 wt.%), with oxidation inhibition observed only at 18 wt.%. At the same time, they demonstrated moderate photocatalytic activity (rate constant 0.256 min⁻¹). These characteristics of the samples correlate with data obtained by microscopy, photoluminescence spectroscopy, and X-ray diffraction analysis. Full article

The global demand for hydrogen peroxide (H₂O₂) continues to increase, and photocatalytic H₂O₂ production is regarded as a promising alternative technology due to its mild, safe, and environmentally friendly characteristics. ZnIn₂S₄ has demonstrated promising application potential in photocatalytic H₂O₂ production owing to its unique two-dimensional layered structure and broad spectral response. However, its performance is severely limited by rapid charge recombination and sluggish charge migration. To address this challenge, a ZnIn₂S₄/C₃N₄ S-scheme heterojunction was successfully constructed via a simple oil-bath method by assembling ZnIn₂S₄ nanoflowers on C₃N₄ nanosheets. Systematic structural characterizations and performance evaluations demonstrate that the construction of the S-scheme heterojunction effectively promotes the spatial separation and surface migration of photogenerated charge carriers, thereby significantly enhancing photocatalytic activity. Under optimal conditions, the ZIS/CN-10 sample (C₃N₄ to ZnIn₂S₄ mass ratio of 10%) achieves the highest photocatalytic H₂O₂ production rate of 825.8 μmol g⁻¹ h⁻¹. This work provides new insights and theoretical guidance for the rational design of efficient and stable ZnIn₂S₄-based photocatalysts. Full article

Conventional food packaging cannot actively regulate spoilage-related molecules such as ethylene and volatile organic compounds that accumulate inside sealed packages. Smart adsorption based nanocatalysts (SABNs) integrate adsorptive scaffolds, catalytic centers, and stimuli responsive triggers to progressively remove these spoilage markers. This review establishes a unified three pillar framework and critically examines how adsorption, catalytic degradation, and regeneration cycles are proposed to function under food-relevant conditions. Across major food categories, reported photocatalytic systems achieve ethylene removal efficiencies of 50% to 90% and extend shelf life by 1 to 5 days under controlled light and temperature. However, performance declines sharply under the dark, humid, and refrigerated conditions typical of real supply chains. A systematic evidence level grading of twelve representative SABN systems reveals that the majority cluster at levels L³ and L⁴, while none has yet reached level L⁵, which requires both standardized migration testing and sensory evaluation. Key barriers, including nanoparticle migration, fragmented regulation, scalability, and life-cycle impacts, are assessed. By introducing explicit inclusion/exclusion criteria and a six-level evidence grading framework, this review maps critical gaps in migration data and cold-chain validation and outlines a staged roadmap toward regulation-ready active packaging technologies. Full article

Antibiotic contamination of water, particularly by tetracycline (TC), requires effective and sustainable treatment strategies. In this study, CoFe₂O₄ nanoparticles were synthesized using lime juice as a natural stabilizing agent and combined with ZnO to obtain a ZnO/CoFe₂O₄ nanocomposite for visible-light-driven TC degradation. Complementary characterization confirmed the coexistence of ZnO and CoFe₂O₄ without detectable secondary phases, with predominantly spherical and irregular particles. The composite exhibited ferromagnetic behavior, suggesting potential magnetic recovery, and showed broader visible-light absorption and a reduced band gap of 3.05 eV compared with 3.23 eV for ZnO. Although its specific surface area and pore volume were lower than those of CoFe₂O₄, the nanocomposite displayed the highest photocatalytic performance. Under the optimized conditions of pH 6, 20 mg L⁻¹ TC, and 1 g L⁻¹ catalyst, 96.8% degradation was achieved after 120 min, with a pseudo-first-order rate constant of 0.029 min⁻¹. The degradation efficiency remained 88.3% after five cycles. Scavenger experiments identified photogenerated holes (h⁺) and hydroxyl radicals (·OH) as the dominant reactive species. The improved photocatalytic activity may be associated with interfacial interactions between ZnO and CoFe₂O₄, suggesting that the green-synthesized nanocomposite has potential as a visible-light photocatalyst for TC degradation under the investigated conditions. Full article