Search Results (1,530)

Commercial alumina and silica–alumina catalysts were investigated for propylene (PEN) production via an isopropanol (IPA) dehydration reaction between 200 and 300 °C at an atmospheric pressure and IPA partial pressure of 5136 Pa. The reaction conditions were chosen to fit with the further conversion of PEN into value-added compounds with minimal capital cost, and the conceptual process design was discussed. The textural properties, structure and chemical composition of as-received and hydrothermally treated catalysts were characterised by the adsorption–desorption of N₂, X-ray fluorescence, X-ray diffraction and Nuclear Magnetic Resonance spectroscopy. The adsorption microcalorimetry of NH₃ and SO₂ was used to determine the amount, strength and strength distribution of acid–base sites, while the nature of the acid sites was investigated by Fourier Transform Infraed spectroscopy. Surface area, pore-size distribution and pore volume were not determining factors for the catalytic performances of studied solids in the conditions used here. The best-performing catalyst combined stable textural properties and a high number of high-strength acid sites (Q_diff > 150 kJ/mol NH₃) under hydrothermal conditions. The importance of determining the number and strength of acid sites of water-aged catalysts, when considering reactions where water is present as reactive or product, is underlined. Full article

Because the interfacial Cu⁰/Cu⁺ in Cu-based electrocatalyst promotes CO₂ electroreduction activity, it would be highly desirable to physically separate Cu-based nanoparticles through coating shells and load them onto porous carriers. Herein, multilayered graphene-coated Cu (Cu@G) nanoparticles with tailorable core diameters (28.2–24.2 nm) and shell thicknesses (7.8–3.0 layers) were fabricated via lased ablation in liquid. A thin Cu₂O layer was confirmed between the interface of the Cu core and the graphene shell, providing an interfacial Cu⁰/Cu⁺. Cu@G cross-linked biochars (Cu@G/Bs) with developed porosity (31.8–155.9 m²/g) were synthesized. Morphology, crystalline structure, porosity, and elemental chemical states of Cu@G and Cu@G/Bs were characterized. Cu@G/Bs captured CO₂ with a maximum sorption capacity of 107.03 mg/g at 0 °C. Furthermore, 95.3–97.1% capture capacity remained after 10 cycles. Cu@G/Bs exhibited the most superior performance with 40.7% of FE_C2H4 and 21.7 mA/cm² of current density at −1.08 V vs. RHE, which was 1.7 and 2.7 times higher than Cu@G. Synergistic integration of developed porosity for efficient CO₂ capture and the fast charge transfer rate of interfacial Cu₂O/Cu enabled this improvement. Favorable long-term stability of the phase/structure and CO₂ electroreduction activity were present. This work provides new insight for integrating Cu@G and a biochar platform to efficiently capture and electro-reduce CO₂. Full article

Wastewater treatment has become a priority in the global attempt to address environmental pollution. Conventional wastewater treatment processes are often limited by their high energy consumption, so it is necessary to develop new technologies. This work shows the results obtained using a passive aerated membraneless microbial fuel cell (PAML-MFC) system consisting of 10 individual units, designed to treat 1000 L/day of real wastewater, using granular activated carbon anodes and cathodes. The pilot-scale water treatment system under study combines design and materials to result in low-cost operation. After 300 days of treating real wastewater originally characterized by a chemical oxygen demand (COD) value of 500 mg/L on average, it was found that the PAML-MFC under study removed 60 to 80% of the COD contained in real wastewater. Under these conditions, the individual MFCs reached an average power density below 1 mW/m³. Full article

The development of low-cost and high-efficiency oxygen evolution reaction (OER) catalysts is essential to enhance the practicality of electrochemical water splitting for green hydrogen production. Layered double hydroxides (LDHs), especially those based on nickel and cobalt, have attracted attention due to their tunable composition, abundant redox-active sites, and earth-abundant constituents. However, their application is hindered by their limited conductivity and sluggish reaction kinetics. In this study, rare-earth-element-doped NiCo LDHs were synthesized directly on nickel foam through a one-step hydrothermal approach to improve the OER activity by modulating the electronic structure and optimizing the surface morphology. Among the representative catalysts, the incorporation of Sm significantly influenced the microstructure and electronic configuration of the catalyst, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical tests showed that the optimized Sm-NiCo LDH achieved a low overpotential of 172 mV at 10 mA cm⁻² and a small Tafel slope of 84 mV dec⁻¹ in 1 M KOH, indicating an expanded electrochemically active surface and improved charge transport. Long-term stability tests further showed its durability. These findings suggest that Sm doping enhances the OER performance by increasing active site exposure and promoting efficient charge transfer, offering a promising strategy for designing rare-earth-modified, non-precious-metal-based OER catalysts. Full article

In this study, a novel strategy to enhance the performance of palladium (Pd)-based catalysts by doping with metal oxides (Mn₃O₄, MoO₃, and SnO) has been developed in order to overcome the limitations of its low activity and high cost in the catalytic oxidation of formaldehyde (HCHO). The novelty of this strategy lies in the fact that by precisely controlling the types and doping ratios of the metal oxides, a significant enhancement of the electrochemical performance and catalytic activity of the Pd-based catalysts was achieved, while the dependence on precious metals was reduced and the cost-effectiveness of the catalysts was improved. The effects of different metal oxide doping on the catalytic performance were systematically investigated by electrochemical characterization and catalytic activity tests. Among the prepared catalysts, Pd-Mn₃O₄ showed the most excellent performance, with an electrochemically active surface area of 20.6 m²/g and a formaldehyde oxidation reaction (FOR) current density of 3.5 mA/cm², which were 31.6% and 169.2% higher than pure Pd, respectively. In a 1000 s timed current method stability test, the limiting current density of Pd-Mn₃O₄ reached 0.48 mA/cm², which is 4.4 times higher than that of pure Pd. The excellent catalytic performance is attributed to the abundant surface hydroxyl (-OH) groups provided by Mn₃O₄, which contribute to the oxidation of formaldehyde intermediates, as well as the electronic synergistic effect between Pd and Mn₃O₄, which is manifested as a 0.4 eV downshift of the Pd 3d binding energy. In addition, the sensor evaluation showed that the Pd-Mn₃O₄-based formaldehyde sensor exhibited a high sensitivity (1.5 μA/ppm), excellent linearity (R² = 0.995), minimal long-term degradation (<7% in 30 days), and ~20-fold selectivity for formaldehyde over interfering gases (e.g., ethanol). This study provides a theoretical basis and practical material reference for the development of efficient and low-cost catalysts for formaldehyde oxidation. Full article

With the increasing severity of global water pollution, traditional wastewater treatment methods have gradually revealed limitations in dealing with complex and refractory pollutants. Advanced oxidation processes (AOPs) have emerged as a promising alternative due to their ability to generate highly reactive radicals (such as hydroxyl and sulfate radicals) that can effectively degrade a wide range of pollutants. This review provides a detailed overview of various AOP technologies, including Fenton processes, ozone-based AOPs, persulfate-based AOPs, photocatalytic AOPs, electrochemical AOPs, and sonochemical AOPs, focusing on their fundamental principles, reaction mechanisms, catalyst design, and application performance in treating different types of wastewater. The research results show that the improved Fenton process can achieve a chemical oxygen demand (COD) removal rate of up to 85% when treating pharmaceutical wastewater. Photocatalytic AOP technology demonstrates higher degradation efficiency when treating industrial wastewater containing refractory pollutants. In addition to effectively degrading refractory pollutants and reducing dependence on traditional biological treatment methods, these advanced oxidation processes can also significantly reduce secondary pollution generated during the treatment process. Moreover, by optimizing AOP technologies, the deep mineralization of harmful substances in wastewater can be achieved, reducing the potential pollution risks to groundwater and soil while also lowering energy consumption during the treatment process. Additionally, this review discusses the challenges faced by AOPs in practical applications, such as high energy consumption, insufficient catalyst stability, and secondary pollution. This review summarizes the research progress and application trends of catalytically driven AOPs in the field of wastewater treatment over the past five years. It aims to provide a comprehensive reference for researchers and engineering professionals on the application of AOPs in wastewater treatment, promoting the further development and practical implementation of these technologies. Full article

Herein, a bi-functional composite photocatalyst was synthesized by integrating carbon nanotubes (CNTs) and graphitic carbon nitride (GCN) via a facile electrostatic self-assembly strategy. The resulting CNTs/GCN composite served dual roles as both a solid emulsifier and a photocatalyst, enabling highly efficient photocatalytic benzyl alcohol oxidation within a Pickering emulsion system. The relationship between emulsion droplet size and solid emulsifier dosage was investigated and optimized. The enhanced photocatalytic function was supported by an improved photocurrent response and reduced charge-transfer resistance, attributed to superior charge separation efficiency. Consequently, the benzyl alcohol conversion efficiency achieved in the Pickering emulsion system (58.9%) was three-fold of that observed in a traditional oil–water non-emulsion system (19.0%). Key active species were identified as photoholes, and an interfacial reaction mechanism was proposed. This work provides a new approach for extending photocatalytic applications in aqueous environments to diverse organic conversion reactions through the construction of multifunctional photocatalysts. Full article

Herein, we rationally designed a molecular catalytic filter for effective micropollutants decontamination via peroxymonosulfate (PMS) activation. Specifically, iron phthalocanine (FePc) molecules with defined Fe–N₄ coordination were immobilized onto carbon nanotubes (CNTs), forming a hybrid catalyst that integrated molecular precision with heterogeneous catalytic properties. The resulting CNT-FePc filter achieved a 98.4% removal efficiency for bisphenol A (10 ppm) in a single-pass operation system, significantly outperforming the CNT/PMS system without FePc (41.6%). Additionally, the CNT-FePc/PMS system demonstrated remarkable resistance to performance inhibition by common water matrix components. Unlike typical radical-dominated PMS activation processes, mechanistic investigations confirmed that the CNT-FePc/PMS system selectively promoted singlet oxygen (¹O₂) generation as the primary oxidative pathway. Density functional theory (DFT) calculations revealed that PMS exhibited stronger adsorption on FePc (−3.05 eV) compared to CNT (−2.86 eV), and that FePc effectively facilitated O–O bond elongation in PMS, thereby facilitating ¹O₂ generation. Additionally, seed germination assays indicated a significant reduction in the biotoxicity of the treated effluents. Overall, this work presents a catalyst design strategy that merges molecular-level coordination chemistry with practical flow-through configuration, enabling rapid, selective, and environmentally benign micropollutant removal. Full article

The rational design of high-performance Cu-SSZ-13 catalysts with enhanced low-temperature activity represents a critical challenge for meeting stringent Euro VII emission standards in diesel aftertreatment systems. Elevating Cu loading can theoretically improve catalytic performance; however, one-time ion exchange using common CuSO₄ solution makes it hard to accomplish high Cu-ion contents. Herein, we demonstrate that the conventional ion-exchange method, adopting Cu(CH₃COO)₂ as precursor in NH₄-SSZ-13 zeolite with a low Si/Al ratio (≈6–7), can achieve higher Cu content while maintaining superior dispersion of active sites. Comprehensive characterizations reveal a dual incorporation mechanism: canonical Cu²⁺ ion exchange and unique adsorption of the [Cu(CH₃COO)]⁺ complex. In the latter case, the surface-adsorbed [Cu(CH₃COO)]⁺ ions form high-dispersion CuO_x species, while the framework-confined ones convert to active Z[Cu²⁺(OH)]⁺ ions. The Cu(CH₃COO)₂-exchanged Cu-SSZ-13 catalyst exhibits superior low-temperature SCR activity and hydrothermal stability to its CuSO₄-exchanged counterpart, making it particularly suitable for close-coupled SCR applications. Our findings provide fundamental insights into Cu speciation control in zeolites and present a scalable, industrially viable approach for manufacturing next-generation SCR catalysts capable of meeting future emission regulations. Full article

This review surveys recent advances and emerging prospects in phase-transfer catalysis (PTC) for fuel desulfurization. In response to increasingly stringent environmental regulations, the removal of sulfur from transportation fuels has become imperative for curbing SO_x emissions. Conventional hydrodesulfurization (HDS) operates under severe temperature–pressure conditions and displays limited efficacy toward sterically hindered thiophenic compounds, motivating the exploration of non-hydrogen routes such as oxidative desulfurization (ODS). Within ODS, PTC offers distinctive benefits by shuttling reactants across immiscible phases, thereby enhancing reaction rates and selectivity. In particular, PTC enables efficient migration of organosulfur substrates from the hydrocarbon matrix into an aqueous phase where they are oxidized and subsequently extracted. The review first summarizes the deployment of classic PTC systems—quaternary ammonium salts, crown ethers, and related agents—in ODS operations and then delineates the underlying phase-transfer mechanisms, encompassing reaction-controlled, thermally triggered, photo-responsive, and pH-sensitive cycles. Attention is next directed to a new generation of catalysts, including quaternary-ammonium polyoxometalates, imidazolium-substituted polyoxometalates, and ionic-liquid-based hybrids. Their tailored architectures, catalytic performance, and mechanistic attributes are analyzed comprehensively. By incorporating multifunctional supports or rational structural modifications, these systems deliver superior desulfurization efficiency, product selectivity, and recyclability. Despite such progress, commercial deployment is hindered by the following outstanding issues: long-term catalyst durability, continuous-flow reactor design, and full life-cycle cost optimization. Future research should, therefore, focus on elucidating structure–performance relationships, translating batch protocols into robust continuous processes, and performing rigorous environmental and techno-economic assessments to accelerate the industrial adoption of PTC-enabled desulfurization. Full article

The methanol oxidation reaction (MOR) of direct methanol fuel cells (DMFCs) is limited by the slow kinetic process and high reaction energy barrier, significantly restricting the commercial application of DMFCs. Therefore, developing MOR catalysts with high activity and stability is very important. In this paper, oxygen-functionalised activated carbon (FAC) with controllable oxygen-containing functional groups was prepared by adjusting the volume ratio of H₂SO₃/HNO₃ mixed acid, and Pd/AC and Pd/FAC catalysts were synthesised via the hydrazine hydrate reduction method. A series of characterisation techniques and electrochemical performance tests were used to study the catalyst. The results showed that when V(H₂SO₃):V(HNO₃) = 2:3, more defects were generated on the surface of the AC, and more oxygen-containing functional groups represented by C=O and C–OH were attached to the surface of the support, which increased the anchor sites of Pd and improved the dispersion of Pd nanoparticles (Pd NPs) on the support. At the same time, the mass–specific activity of Pd/FAC for MOR was 2320 mA·mg_Pd, which is 1.5 times that of Pd/AC, and the stability was also improved to a certain extent. In situ infrared spectroscopy further confirmed that oxygen functionalisation treatment promoted the formation and transformation of *COOH intermediates, accelerated the transformation of CO_L into CO_B, reduced the poisoning of CO_ads species adsorbed to the catalyst, optimised the reaction path and improved the catalytic kinetic performance. Full article

Catalysts are ubiquitous in manufacturing industries and gas phase pollutant abatement but are not widely used in wastewater treatment, as high temperatures and concentrated waste streams are needed to achieve the reaction degradation rates required. Heating water is energy intensive, and alternative, low temperature solutions have been investigated, collectively known as advanced oxidation processes. However, many of these advanced oxidation processes use expensive oxidants such as perchlorate, hydroxy radicals or ozone to react with contaminants, and therefore have high running costs. This study has investigated microwave catalysis as a low-energy, low-cost technology for water treatment using NiO catalysts that can be heated in the microwave field to drive the decomposition of azo-dye contaminants. Using this methodology for the microwave-assisted degradation of two azo dyes (azorubine and methyl orange), conversions of >95% were achieved in only 10 s with 100 W microwave power. Full article

Biosynthesized ZnO nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible (UV-vis) spectroscopy, and Fourier transform–infrared (FT-IR) spectroscopy. XRD confirmed a hexagonal wurtzite phase with an average crystallite size of 36.44 nm, while UV-vis spectroscopy showed a distinct absorption peak at 321 nm. The Zeta potential of the ZnO nanostructures was −24.28 mV, indicating high stability in suspension, which is essential for their dispersion and functionality in biological and environmental applications. The nematicidal activity of ZnO was evaluated in vitro at concentrations of 150, 300, 450, and 600 ppm, with the highest concentration achieving 75.71% mortality of second-stage juveniles (J2s) after 72 h. The calculated LC₅₀ values for the treatments were 270.33 ppm at 72 h. Additionally, molecular docking studies indicated significant interactions between the ZnO nanostructures and nematode proteins, HSP-90 and ODR1, supporting their potential nematicidal mechanism. This research highlights the effectiveness of neem leaf extract-mediated ZnO nanostructures as an eco-friendly, sustainable alternative for nematode control, presenting a promising solution for agricultural pest management. Full article

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a class of synthetic fluorine-containing organic compounds that exhibit chemical and thermal stability due to the highly stable carbon–fluorine bonds present in their molecular structures. This characteristic makes them slow to degrade in the natural environment. With the widespread application of these compounds in the industrial and consumer goods sectors, environmental media such as water, air, soil, and food have been severely polluted, posing a range of significant threats to public health. Therefore, the development of efficient, economical, and environmentally friendly PFAS removal technologies has become a current research hotspot. This review systematically summarizes the current technologies for removing PFASs from four perspectives—physical, chemical, biological, and combined treatments—enabling a clear understanding of the existing treatment strategies to be discussed. In addition, suggestions for future research on PFAS removal are provided. Full article

Surface segregation in bimetallic systems plays a critical role in material functionality, as electrochemical activity and catalytic performance are governed by the surface composition. To explore the influence of atomic oxygen on the surface composition of Pd–Ti alloys, density functional theory (DFT) simulations were utilized to analyze Ti segregation within Pd matrices. The adsorption behavior of atomic oxygen on Pd–Ti low-index (111), (100), and (110) surfaces was systematically investigated through energetic and electronic analyses. Simulation results reveal that Ti atoms prefer to remain in the bulk of the alloy under vacuum conditions, whereas oxygen adsorption induces significant Ti segregation to the surface layer. This oxygen-driven segregation is mechanistically linked to oxygen-surface bonding strength, as evidenced by correlating adsorption energetics with electronic structure modifications. These results provide a theoretical basis for engineering Pd–Ti alloys as high-performance catalysts in the oxygen reduction reaction. Full article