Search Results (3,899)

The continuous tightening of emission regulations and the escalating costs of palladium (Pd) and rhodium (Rh) have renewed interest in platinum (Pt)-based three-way catalysts (TWCs) as cost-effective alternatives for gasoline aftertreatment. However, despite extensive studies on Pt/CeO₂ and Pt/Ba-based formulations, the cooperative roles of Ba and Ce and, in particular, the fundamental influence of the Ba/Ce ratio on oxygen mobility, NO_x storage behavior, and Pt–support interactions remain poorly understood. In this work, we address this gap by systematically tuning the Ba/Ce molar ratio in a series of Pt–Ba–Ce/Al₂O₃ catalysts prepared from Ba(CH₃COO)₂ and CeO₂ precursors, and evaluating their structure–function relationships in both fresh and hydrothermally aged states. Through comprehensive characterization (N₂ physisorption, XRD, XPS, H₂-TPR, NO_x-TPD, SEM, CO pulse adsorption, and dynamic light-off testing), we establish previously unrecognized correlations between Ba/Ce ratio–dependent structural evolution and TWC performance. The results reveal that the Ba/Ce ratio exerts a decisive control over catalyst textural properties, Pt dispersion, and interfacial Pt–CeO₂ oxygen species. Low Ba/Ce ratios uniquely promote Pt–Ce interfacial oxygen and O₂ spillover—providing a new mechanistic basis for enhanced low-temperature oxidation and reduction reactions—while higher Ba loading selectively drives BaCO₃ formation and boosts NO_x storage capacity. A clear volcano-type dependence of NO_x storage on the Ba/Ce ratio is demonstrated for the first time. Hydrothermal aging at 850 °C induces PtO_x decomposition, BaCO₃–Al₂O₃ solid-state reactions forming inactive BaAl₂O₄, and Pt sintering, collectively suppressing Pt–Ce interactions and reducing TWC activity. Importantly, an optimized Ba/Ce ratio is shown to mitigate these degradation pathways, offering a new design principle for thermally durable Pt-based TWCs. Overall, this study provides new mechanistic insight into Ba–Ce cooperative effects, establishes the Ba/Ce ratio as a critical and previously overlooked parameter governing Pt–support interactions and NO_x storage, and presents a rational strategy for designing cost-effective, hydrothermally robust Pt-based alternatives to Pd/Rh commercial TWCs. Full article

A comparative study on the adsorption of ciprofloxacin (CIP) and sulfamethoxazole (SMX) onto CO₂-activated biochars derived from leather tannery waste (ABT) and Sargassum brown macroalgae (ABS) is presented. N₂ physisorption revealed that ABS possesses a higher Langmuir surface area (1305 m²/g) and a hierarchical micro–mesoporous structure, whereas ABT exhibits a lower surface area (412 m²/g) and a predominantly microporous texture. CHNS and FTIR analyses confirmed the presence of N-, O-, and S-containing heteroatoms and functional groups on both adsorbents, enhancing surface reactivity. Adsorption isotherms fitted well to the Langmuir model, with ABS showing superior maximum capacities of 256.41 mg/g (CIP) and 256.46 mg/g (SMX) compared to ABT (210.13 and 213.00 mg/g, respectively). Kinetic data followed a pseudo-second-order model (R² > 0.998), with ABS exhibiting faster uptake due to its mesoporosity. Over eight reuse cycles, ABS retained >75% removal efficiency for both antibiotics, while ABT declined to 60–70%. pH-dependent adsorption behavior was governed by the point of zero charge (pH_PZC≈ 9.0 for ABT; ≈7.2 for ABS), influencing electrostatic and non-electrostatic interactions. These findings demonstrate that ABS is a highly effective, sustainable adsorbent for antibiotic removal in water treatment applications. Full article

Photocatalytic reduction of carbon dioxide is a very effective strategy to address the energy crisis and greenhouse effect. TiO₂ is a widely used semiconductor photocatalyst, which has excellent catalytic activity, excellent chemical stability and low toxicity. Nevertheless, TiO₂ still has some inherent limitations, such as: wide band gap, high carrier recombination rate, and low adsorption activation ability for carbon dioxide. These drawbacks severely restrict its further application in the photocatalytic reduction of CO₂. In this study, cotton-like blue C/TiO₂ NTs are successfully synthesized through the in situ growth of TiO₂ nanotubes on the MIL-125(Ti)-derived C/TiO₂ precursor. The experimental results revealed that the CO production rate of the cotton-like blue C/TiO₂ NTs was 1.84 times that of C/TiO₂ and 3.78 times that of TiO₂ nanotubes. These results clearly demonstrate that the cotton-like blue C/TiO₂ NTs exhibit a broad spectral response, a large specific surface area, and an abundance of oxygen vacancies. This research provides new insights into the design of titanium dioxide-based photocatalytic materials and opens up a promising avenue for enhancing the performance of titanium dioxide in the photocatalytic reduction of carbon dioxide. Full article

This work aims to adsorb CO and CO₂ using a low-cost biogenic waste (bone) as a platform for the in situ growth of HKUST-1, employing two methodologies. The synthesized composite materials, BMOF2 and BMOF3, exhibited functional, textural, and structural characteristics that were modulated by the MOF growth pathway. SEM, RXD, FTIR, XPS, and the N₂ adsorption–desorption isotherm confirmed the growth of HKUST-1. Both methodologies yield the same MOF, but differ in surface area and shape. The relative and total coverage percentages were determined, as well as the apparent selectivity at a fixed time, establishing direct correlations between the structural and textural differences in the materials and their dynamic performance in the presence of both gases. Although the adsorption capacities obtained do not exceed those of other MOFs, the results from BMOF2 and BMOF3 demonstrate that the efficiency of an adsorbent depends not only on its capacity but also on its technological feasibility, including rapid processing and high capacities. The combination of abundant availability, a simple, sustainable, and reproducible synthetic route, and competitive performance makes these compounds viable alternatives for large-scale applications. Incorporating HKUTS-1 into bone as a functional material is a promising approach to developing new compounds for gas capture in the treatment of gas streams. Full article

Alkaline treatment in 0.2 and 0.4 M NaOH solutions successfully generated controlled mesoporosity into ZSM-5 (Zeolite Socony Mobil-5) zeolite, resulting in average mesopore diameters of approximately 15 and 25 nm, respectively, while preserving the crystalline structure of the zeolite framework. Parent ZSM-5 and its mesoporous derivatives obtained by desilication were used to prepare (Fe species)@(zeolite matrix) composites. The synthesis was carried out by co-precipitating Fe²⁺/Fe³⁺ ions onto both parent and desilicated ZSM-5 matrices under oxygen-free conditions. Comprehensive characterization by X-ray diffraction, scanning electron microscopy, N₂ adsorption, vibrating-sample magnetometry, ⁵⁷Fe Mössbauer spectroscopy, and diffuse reflectance UV–Vis spectroscopy revealed that the degree of introduced mesoporosity dramatically influences the size, dispersion, phase composition, and oxidation state of the iron-containing nanospecies. On purely microporous ZSM-5, relatively large (~15 nm) partially oxidized magnetite nanoparticles are formed predominantly on the external surface, exhibiting superparamagnetism at room temperature (Mₛ = 11 emu/g) and a band gap of 2.12 eV. Increasing mesoporosity leads to progressively smaller and more highly dispersed iron(III) oxo/hydroxo clusters with significantly lower blocking temperatures and reduced magnetization (down to 0.7 emu/g for Fe@ZSM-5_0.4). All composites display strong visible-light absorption confirming their potential as magnetically separable visible-light-driven photocatalysts for environmental remediation. Full article

Environmental pollution from ozone and wastewaters containing dyes from various industries is an important problem for humanity. In this study, novel composite catalysts based on manganese carbonate ore from the Obrochishte deposit, Bulgaria, were used successfully in two environmentally relevant catalytic processes—the ozone decomposition and photocatalytic decolourization of Malachite Green (MG) dye under UV illumination. Manganese carbonate ore/NiO, manganese oxides, and silver-containing composites were synthesized via co-precipitation, followed by calcination at 500 °C or hydrothermal treatment at 160 °C, and then thermal treatment. The phase and elemental composition, structure, morphology, and textural characteristics of the obtained composites were investigated using powder X-ray diffraction analysis, wavelength-dispersive X-ray fluorescence, Fourier-transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and the BET method. The materials exhibit a mesoporous structure. The results established that the thermally treated MnCO₃ ore/NiO, manganese oxides, and Ag-containing composites demonstrate a higher catalytic efficiency for the removal of ozone (85%, 93%, and 99%) in comparison with hydrothermally treated analogues—79%, 66%, and 98%, respectively. The thermally treated manganese carbonate ore/silver-containing composite exhibits the highest photocatalytic ability (83% degree of decolourization of MG dye) compared to the other investigated catalysts. Full article

Chemical looping combustion (CLC) is a promising technology for CO₂ capture, with the performance of the system largely dependent on the oxygen carrier. Although Ni-based carriers have been extensively investigated, their practical application is still constrained by inadequate reactivity. This study investigated the doping of alkali metals (Li, Na, K) into NiO to improve its performance in CLC. Through density functional theory calculations, the structural, electronic, and reactivity of doped NiO surfaces were systematically analyzed. Results reveal that doping induces lattice expansion and enhances CO adsorption, with adsorption energies strengthening to −0.53 eV for Li, −0.46 eV for Na, and −0.36 eV for K. Furthermore, alkali metal doping significantly reduces the energy barrier for CO₂ formation from 2.12 eV on pure NiO to 0.73 eV, 0.80 eV, and 0.99 eV on Li-, Na-, and K-doped surfaces, respectively. Oxygen vacancy formation energy also decreases from 3.60 eV to as low as 2.90 eV for K-doping, indicating markedly improved oxygen activity. Electronic structure analysis confirms that doping facilitates electron transfer and stabilizes key reaction intermediates. In conclusion, alkali metal doping substantially enhances the redox activity of NiO, providing an effective strategy for developing high-performance oxygen carriers in CLC. Full article

Four new porous homochiral metal–organic frameworks (MOFs), [M₂(camph)₂(bpa)]∙Solv (M = Co(II), Ni(II), Cu(II) and Zn(II)), based on (+)-camphoric acid (H₂camph) and 1,2-bis(4-pyridyl)ethane (bpa) were synthesized and characterized. The crystal structures of [Ni₂(camph)₂(bpa)] and [Zn₂(camph)₂(bpa)] were established by single-crystal X-ray diffraction analysis. Powder X-ray data prove the phase purity and isostructural nature of all four compounds. The thermal stability of [M₂(camph)₂(bpa)] was found to depend on the electronic configuration, as well as on the redox properties of the metal cation, and varied from 225 °C (M = Zn²⁺) to 375 °C (M = Ni²⁺). The reversible, solvent-induced sponge-like dynamics of the coordination frameworks was thoroughly investigated. Changes in the positions of reflexes, related to the length of the flexible bpa linker, were observed by powder XRD, pointing to transitions between an open-framework phase and a squeezed, non-porous phase in a crystal-to-crystal manner, while the integrity and connectivity of the coordination network were maintained. Size-selective adsorption from a benzene–cyclohexane 1:1 mixture on [Zn₂(camph)₂(bpa)] was studied by ¹H NMR analysis. The benzene-favorable composition of guest molecules (C₆H₆:C₆H₁₂ = 5:1) occluded within the host crystalline sponge revealed a preferable adsorption affinity towards smaller benzene compared with larger cyclohexane. High framework stability in various solvents, as well as successful molecular separation in the liquid state, validates the potential utilization of chiral porous metal(II) camphorate MOFs in important stereoselective applications. Full article

To improve the electrocatalytic methanol oxidation (MOR) performance of platinum (Pt)-based catalysts in direct methanol fuel cells (DMFCs), this study uses phosphorus-doped carbon nanotubes (P-CNTs) as a support material. Through a hydrothermal method, different proportions of potassium bromide (KBr) are introduced as a structural directing agent to prepare a series of Pt/P-CNTs-M catalysts (where M represents the molar ratio of KBr to Pt). The study systematically investigates the mechanism by which KBr regulates the crystal plane of Pt nanoparticles and its structure–activity relationship. Physical characterization revealed that KBr selectively regulates Pt crystal plane growth through Br⁻ adsorption. When M = 30, Pt/P-CNTs-30 exhibited the highest proportion of exposed Pt(111) crystal planes (27.21%), with Pt⁰ content reaching 51.64%, and featured moderate particle size (2.22 nm) and uniform dispersion. Electrochemical testing indicates that the MOR mass-specific activity of this catalyst reaches 3559.85 mA·mg⁻¹_Pt, which is 1.17 times that of Pt/P-CNTs-0; it exhibits the lowest charge transfer impedance, with a current density of 488.25 mA·mg⁻¹_Pt still maintained after 3600 s of chronoamperometry testing, and a more negative CO oxidation onset potential, demonstrating optimal resistance to poisoning. The study indicates that an appropriate KBr ratio can synergistically optimize Pt crystal plane structure and electronic states, providing a theoretical basis for the design of high-efficiency fuel cell catalysts. Full article

Background: Cisplatin resistance is a major obstacle in the treatment of Hepatocellular carcinoma (HCC), characterized by reduced intracellular drug accumulation and altered DNA repair/apoptosis signaling. Methods: To address this challenge, we developed an acid-responsive nanoplatform consisting of a cisplatin-loaded CaCO₃ core with a lipid coating that enables surface adsorption of Bmi1 siRNA, termed LCa/C@B. Results: These nanoparticles are subsequently coated with positively charged phospholipids, facilitating the absorption of Bmi1 siRNA. In vitro, LCa/C@B markedly enhanced intracellular cisplatin accumulation, downregulated Bmi1 and cancer stem cell (CSC) markers, and restored chemosensitivity in HepG2/MDR cells. In vivo, LCa/C@B achieved improved tumor localization, significant Bmi1 knockdown, suppression of CSC populations, and robust inhibition of tumor growth in a primary HCC model. Importantly, the dual-targeting design produced a synergistic therapeutic effect superior to free cisplatin or single-component formulations. Conclusions: This hybrid drug delivery system, combining calcium carbonate and cisplatin with Bmi1 siRNA, presents a promising approach for overcoming chemotherapy resistance in HCC. Full article

GenX, also known as hexafluoroepoxypropane dimer acid (HFPO-DA), an emerging perfluoroalkyl substance alternative, is extensively used in industrial processes and is resistant to degradation. This persistence heightens the potential for co-occurrence and combined toxicity with other environmental pollutants. Nanoplastics (NPs), ubiquitous environmental contaminants, can exacerbate the biological toxicity of GenX. However, the molecular mechanisms by which NPs influence GenX-induced structural damage to human serum albumin (HSA) remain unclear. This study, therefore, employed multi-spectroscopic techniques, characterization assays, and molecular simulations to investigate these mechanisms. A critical limitation is that the observed structural damage occurred at a GenX concentration of 0.05–0.1 mM. The results indicate that the presence of NPs exacerbated the loosening of the protein backbone and caused a more pronounced reduction in α-helical content (NPs@GenX: 37.3%; GenX alone: 41.5%). The binding is predicted to occur within the hydrophobic pocket of subdomain IIIA of HSA. Characterization assays further revealed significant protein aggregation in systems containing NPs. The study concludes that NPs adsorb HSA through the formation of a protein corona, while simultaneously binding GenX via hydrophobic interactions. This dual pathway—direct binding of HSA to GenX and an active surface-mediated perturbation by NPs—constitutes the primary mechanism leading to aggravated structural changes. Overall, this work elucidates the molecular mechanisms by which NPs exacerbate HSA denaturation in the presence of GenX, offering valuable insights for assessing the combined ecological risks of emerging and persistent environmental pollutants. Full article

This study investigates the materials and fabrication selection criteria for 3D-printed aluminosilicate components aimed for passive cooling and CO₂ adsorption in indoor conditions, considering their manufacturing environmental impact. The dual-function components were fabricated using Liquid Deposition Modelling (LDM), an Additive Manufacturing (AM) technique utilising customised slurry-based feedstock materials. To assess the environmental implications of the production process, the study employs the Life Cycle Assessment (LCA) methodology, a standardised framework used to quantify potential environmental impacts across the product’s life cycle. The study outlines a systematic approach to materials and fabrication processes selection, focusing on the functional properties required, the importance of locally sourced materials, and the constraints imposed by the fabrication techniques. The fabrication methodology was analysed for material/energy efficiency and waste generation. Post-processing stages were evaluated to identify opportunities for energy savings, particularly by exploring Low-Temperature Firing (LTF). The selected criteria proved efficient in enhancing shaping control and minimising shrinkage variability, with a recorded weight loss of 3.04% via LTF. The LCA results indicated that the 23% reduction in climate change impact was primarily driven by the lower electricity demand of the LTF Protocol, demonstrating that energy-efficient post-processing is a critical lever for sustainable ceramic fabrication. Full article

Vitamin D₃ (VD3) is an essential micronutrient, but its analytical determination in biological matrices is often hindered by structurally related metabolites and the limited selectivity of conventional analytical sorbents. The preparation of a molecularly imprinted polymer (MIP) using VD3 as a template is challenging due to its hydrophobic structure and lack of polar groups. Therefore, in this work, MIPs were prepared using the closely related structure hyodeoxycholic acid methyl ester as a template and tested for their adsorption capacity toward VD3. Several MIPs were first prepared using different functional monomers, and the results showed that 4-vinylpyridine (4VP) monomer in combination with divinylbenzene (DVB) as a crosslinker exhibited a relatively high binding capacity and imprinting factor. UV spectroscopy indicated an optimal VD3–monomer ratio of 1:4, while computational modeling further confirmed favorable interactions between VD3 and 4VP. The effect of incorporating styrene as a co-monomer with 4VP was also investigated, showing an enhancement in adsorption capacity with a slight increase in the imprinting factor. However, TGA analysis revealed that the thermal stability of the MIPs decreased with higher styrene content. Overall, the prepared MIPs demonstrated improved selectivity and recognition of VD3 compared to the non-imprinted polymers, offering a promising approach for its selective extraction and quantification. Full article

Direct Air Capture (DAC) technology plays a crucial role in reducing atmospheric CO₂, but large-scale deployment faces challenges such as high energy consumption, operational costs, and slow material development. This study provides a comprehensive review of DAC principles, including chemical and solid adsorption methods, with a focus on emerging technologies like Metal–Organic Frameworks (MOFs) and graphene aerogels. MOFs have achieved adsorption capacities up to 1.5 mmol/g, while modified graphene aerogels reach 1.3 mmol/g. Other advancing approaches include DAC with Methanation (DACM), variable-humidity adsorption, photo-induced swing adsorption, and biosorption. The study also examines global industrialization trends, noting a significant rise in DAC projects since 2020, particularly in the U.S., China, and Europe. The integration of DAC with renewable energy sources, such as photovoltaic/electrochemical regeneration, offers significant cost-reduction potential and can cut reliance on conventional heat by 30%. This study focuses on the integration of Artificial Intelligence (AI) for accelerating material design and system optimization. AI and Machine Learning (ML) are accelerating DAC R&D: high-throughput screening shortens material design cycles by 60%, while AI-driven control systems optimize temperature, humidity, and adsorption dynamics in real time, improving CO₂ capture efficiency by 15–20%. The study emphasizes DAC’s future role in achieving carbon neutrality through enhanced material efficiency, integration with renewable energy, and expanded CO₂ utilization pathways, providing a roadmap for scaling DAC technology in the coming years. Full article

Soda saline–alkaline soils have seriously restricted the sustainable development of agriculture in the Songnen Plain, China. Applying soil amendments has proven to be an effective remediation strategy for these sodic soils; however, conventional amendments face limitations, including prolonged remediation periods and the potential to cause secondary pollution upon misapplication. In this study, we combined three different amendments and applied them as four distinct treatments—citric acid + nano-silica (CS), citric acid + nano-silica + humic acid (CSH), nano-silica + humic acid (SH), and citric acid + humic acid (CH)—with no amendment used as the control (CK). The effects of these treatments on improving the soda saline–alkali soil was evaluated using a field positioning experiment. The results indicate that, compared to the CK treatment, applying the amendments significantly increased the concentrations of available phosphorus (AP) (9.19% to 44.43%) and organic matter (SOM) (3.53% to 16.48%) while decreasing alkalinity and salinity indicators (pH, EC (electrical conductivity), ESP (exchangeable sodium percentage), SAR (sodium adsorption ratio), and TA (total alkalinity)) and soil alkali stress ions (water-soluble and exchangeable Na⁺, CO₃²⁻, and HCO₃⁻). The partial least squares path modeling analysis (PLS-PM) demonstrated that the application of the amendments improved soil quality by changing its alkalinity and ion composition, thereby increasing the maize yield (from 3.01% to 9.80%). Full article