Understanding Catalytic Mechanisms and Cathode Interface Kinetics in Nonaqueous Mg-CO2 Batteries

We leverage first-principles density functional theory (DFT) calculations to understand the electrocatalytic processes in Mg-CO2 batteries, considering ruthenium oxide (RuO2) as an archetypical cathode catalyst. Our goal is to establish a mechanistic framework for understanding the charging and discharging reaction pathways and their influence on overpotentials. On the RuO2 (211) surface, we found reaction initiation through thermodynamically favorable adsorption of Mg followed by interactions with CO2. However, we found that the formation of carbonate (CO32-) and oxalate (C2O42-) intermediates via the activation of CO2 at the catalytic site is thermodynamically unfavorable. We predict that MgC2O4 will form as the discharge product due to its lower overpotential compared to MgCO3. However, MgC2O4 is thermodynamically unstable and is expected to decompose into MgCO3, MgO, and C as final discharge products. Through Bader charge analysis, we investigate the covalent interactions between intermediates and catalyst sites. Moreover, we study the electrochemical free energy profiles of the most favorable reaction pathways and determine discharge and charge overpotentials of 1.30 and 1.35 V, respectively. Our results underscore the importance of catalyst design for the cathode material to overcome performance limitations in nonaqueous Mg-CO2 batteries.

Combined Electrospinning-Electrospraying for High-Performance Bipolar Membranes with Incorporated MCM-41 as Water Dissociation Catalysts

Electrospinning has been demonstrated as a very promising method to create bipolar membranes (BPMs), especially as it allows three-dimensional (3D) junctions of entangled anion exchange and cation exchange nanofibers. These newly developed BPMs are relevant to demanding applications, including acid and base production, fuel cells, flow batteries, ammonia removal, concentration of carbon dioxide, and hydrogen generation. However, these applications require the introduction of catalysts into the BPM to allow accelerated water dissociation, and this remains a challenge. Here, we demonstrate a versatile strategy to produce very efficient BPMs through a combined electrospinning-electrospraying approach. Moreover, this work applies the newly investigated water dissociation catalyst of nanostructured silica MCM-41. Several BPMs were produced by electrospraying MCM-41 nanoparticles into the layers directly adjacent to the main BPM 3D junction. BPMs with various loadings of MCM-41 nanoparticles and BPMs with different catalyst positions relative to the junction were investigated. The membranes were carefully characterized for their structure and performance. Interestingly, the water dissociation performance of BPMs showed a clear optimal MCM-41 loading where the performance outpaced that of a commercial BPM, recording a transmembrane voltage of approximately 1.11 V at 1000 A/m2. Such an excellent performance is very relevant to fuel cell and flow battery applications, but our results also shed light on the exact function of the catalyst in this mode of operation. Overall, we demonstrate clearly that introducing a novel BPM architecture through a novel hybrid electrospinning-electrospraying method allows the uptake of promising new catalysts (i.e., MCM-41) and the production of very relevant BPMs.

From Waste to Resource: Valorization of Lignocellulosic Agri-Food Residues through Engineered Hydrochar and Biochar for Environmental and Clean Energy Applications-A Comprehensive Review

Agri-food residues or by-products have increased their contribution to the global tally of unsustainably generated waste. These residues, characterized by their inherent physicochemical properties and rich in lignocellulosic composition, are progressively being recognized as valuable products that align with the principles of zero waste and circular economy advocated for by different government entities. Consequently, they are utilized as raw materials in other industrial sectors, such as the notable case of environmental remediation. This review highlights the substantial potential of thermochemical valorized agri-food residues, transformed into biochar and hydrochar, as versatile adsorbents in wastewater treatment and as promising alternatives in various environmental and energy-related applications. These materials, with their enhanced properties achieved through tailored engineering techniques, offer competent solutions with cost-effective and satisfactory results in applications in various environmental contexts such as removing pollutants from wastewater or green energy generation. This sustainable approach not only addresses environmental concerns but also paves the way for a more eco-friendly and resource-efficient future, making it an exciting prospect for diverse applications.

Bimetallic Nanoalloy Catalysts for Green Energy Production: Advances in Synthesis Routes and Characterization Techniques

Bimetallic Nanoalloy catalysts have diverse uses in clean energy, sensing, catalysis, biomedicine, and energy storage, with some supported and unsupported catalysts. Conventional synthetic methods for producing bimetallic alloy nanoparticles often produce unalloyed and bulky particles that do not exhibit desired characteristics. Alloys, when prepared with advanced nanoscale methods, give higher surface area, activity, and selectivity than individual metals due to changes in their electronic properties and reduced size. This review demonstrates the synthesis methods and principles to produce and characterize highly dispersed, well-alloyed bimetallic nanoalloy particles in relatively simple, effective, and generalized approaches and the overall existence of conventional synthetic methods with modifications to prepare bimetallic alloy catalysts. The basic concepts and mechanistic understanding are represented with purposely selected examples. Herein, the enthralling properties with widespread applications of nanoalloy catalysts in heterogeneous catalysis are also presented, especially for Hydrogen Evolution Reaction (HER), Oxidation Reduction Reaction (ORR), Oxygen Evolution Reaction (OER), and alcohol oxidation with a particular focus on Pt and Pd-based bimetallic nanoalloys and their numerous fields of applications. The high entropy alloy is described as a complicated subject with an emphasis on laser-based green synthesis of nanoparticles and, in conclusion, the forecasts and contemporary challenges for the controlled synthesis of nanoalloys are addressed.

Reducibility of Al3+-Modified Co3O4: Influence of Aluminum Distribution

The reduction of Co-based oxides doped with Al3+ ions has been studied using in situ XRD and TPR techniques. Al3+-modified Co3O4 oxides with the Al mole fraction Al/(Co + Al) = 1/6; 1/7.5 were prepared via coprecipitation, with further calcination at 500 and 850 °C. Using XRD and HAADF-STEM combined with EDS element mapping, the Al3+ cations were dissolved in the Co3O4 lattice; however, the cation distribution differed and depended on the calcination temperature. Heating at 500 °C led to the formation of an inhomogeneous (Co,Al)3O4 solid solution; further treatment at 850 °C provoked the partial decomposition of mixed Co-Al oxides and the formation of particles with an Al-depleted interior and Al-enriched surface. It has been shown that the reduction of cobalt oxide by hydrogen occurs via the following transformations: (Co,Al)3O4 → (Co,Al)O → Co. Depending on the Al distribution, the course of reduction changes. In the case of the inhomogeneous (Co,Al)3O4 solid solution, Al stabilizes intermediate Co(II)-Al(III) oxides during reduction. When Al3+ ions are predominantly on the surface of the Co3O4 particles, the intermediate compound consists of Al-depleted and Al-enriched Co(II)-Al(III) oxides, which are reduced independently. Different distributions of elemental Co and Al in mixed oxides simulate different types of the interaction phase in Co3O4/γ-Al2O3-supported catalysts. These changes in the reduction properties can significantly affect the state of an active component of the Co-based catalysts.

Hyper-Crosslinked Porous Organic Nanomaterials: Structure-Oriented Design and Catalytic Applications

Hyper-crosslinked porous organic nanomaterials, especially the hyper-crosslinked polymers (HCPs), are a unique class of materials that combine the benefits of high surface area, porous structure, and good chemical and thermal stability all rolled into one. A wide range of synthetic methods offer an enormous variety of HCPs with different pore structures and morphologies, which has allowed HCPs to be developed for gas adsorption and separations, chemical adsorption and encapsulation, and heterogeneous catalysis. Here, we present a systematic review of recent approaches to pore size modulation and morphological tailoring of HCPs and their applications to catalysis. We mainly compare the effects of pore size modulation and morphological tailoring on catalytic applications, aiming to pave the way for researchers to develop HCPs with an optimal performance for modern applications.

Recent progress in metal assisted multicomponent reactions in organic synthesis

To prepare complicated organic molecules, straightforward, sustainable, and clean methodologies are urgently required. Thus, researchers are attempting to develop imaginative approaches. Metal-catalyzed multicomponent reactions (MCRs) offer optimal molecular diversity, high atomic efficiency, and energy savings in a single reaction step. These versatile protocols are often used to synthesize numerous natural compounds, heterocyclic molecules, and medications. Thus far, the majority of metal-catalyzed MCRs under investigation are based on metal catalysts such as copper and palladium; however, current research is focused on developing novel, environmentally friendly catalytic systems. In this regard, this study demonstrates the effectiveness of metal catalysts in MCRs. The aim of this study is to provide an overview of metal catalysts for safe application in MCRs.

Optimizing study on the NH3-SCR activity of Ce-W-Ti@g-C3N4 catalyst: influence of graphite carbon nitride types

Herein, three g-C3N4(MCN/TCN/UCN), obtained by the direct pyrolysis of melamine/urea/thiourea respectively, were introduced as supports to optimize the NH3-SCR activity of Ce-W-Ti catalyst. Compared to CWT-400-Air, CWT@g-C3N4(2)-300-N2 exhibits lower crystalline anatase TiO2 and larger specific surface area, which improves the dispersion of Ce/W/Ti species on catalysts surface. Furthermore, the introduction of g-C3N4 as supports also contributes to doping C/N elements into Ce-W-Ti catalyst and increases the Ce3+/(Ce3++Ce4+) and Oα/(Oα+Oβ) molar ratios on catalyst surface. These all are advantageous to the NH3-SCR activity. However, UCN shows better promotional effect than MCN and TCN. This might be mainly attributed to the loose and porous stacked layered fold structure of UCN, the larger BET surface area, higher dispersion of Ce/W/Ti species and moderate weak/medium-strong acid sites of CWT@UCN(2)-300-N2. At the same time, the influence of carbon nitride amount, calcination atmosphere and calcination temperature on the NH3-SCR activity of CWT@g-C3N4 catalyst were also investigated.

Microwave-Assisted Synthesis of Pt/SnO2 for the Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol

In this study, we present a new approach for the synthesis of Pt/SnO2 catalysts using microwave radiation. Pt(IV) and Sn(IV) inorganic precursors (H2PtCl6 and SnCl4) and ammonia were used, which allowed the controlled formation of platinum particles on the anisotropic SnO2 support. The synthesized Pt/SnO2 samples are mesoporous and exhibit a reversible physisorption isotherm of type IV. The XRD patterns confirmed the presence of platinum maxima in all Pt/SnO2 samples. The Williamson-Hall diagram showed SnO2 anisotropy with crystallite sizes of ~10 nm along the c-axis (< 00l >) and ~5 nm along the a-axis (< h00 >). SEM analysis revealed anisotropic, urchin-like SnO2 particles. XPS results indicated relatively low average oxidation states of platinum, close to Pt metal. 119Sn Mössbauer spectroscopy indicated electronic interactions between Pt and SnO2 particles. The synthesized samples were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess NaBH4. The catalytic activity of the Pt/SnO2 samples for the reduction of 4-NP to 4-AP was optimized by varying the synthesis parameters and Pt loading. The optimal platinum loading for the reduction of 4-NP to 4-AP on the anisotropic SnO2 support is 5 mol% with an apparent rate constant k = 0.59 × 10-2 s-1. The Pt/SnO2 sample showed exceptional reusability and retained an efficiency of 81.4% after ten cycles.

Quantifying Atomically Dispersed Catalysts Using Deep Learning Assisted Microscopy

The catalytic performance of atomically dispersed catalysts (ADCs) is greatly influenced by their atomic configurations, such as atom-atom distances, clustering of atoms into dimers and trimers, and their distributions. Scanning transmission electron microscopy (STEM) is a powerful technique for imaging ADCs at the atomic scale; however, most STEM analyses of ADCs thus far have relied on human labeling, making it difficult to analyze large data sets. Here, we introduce a convolutional neural network (CNN)-based algorithm capable of quantifying the spatial arrangement of different adatom configurations. The algorithm was tested on different ADCs with varying support crystallinity and homogeneity. Results show that our algorithm can accurately identify atom positions and effectively analyze large data sets. This work provides a robust method to overcome a major bottleneck in STEM analysis for ADC catalyst research. We highlight the potential of this method to serve as an on-the-fly analysis tool for catalysts in future in situ microscopy experiments.

Recent Progress of Layered Double Hydroxide-Based Materials in Wastewater Treatment

Layered double hydroxides (LDHs) can be used as catalysts and adsorbents due to their high stability, safety, and reusability. The preparation of modified LDHs mainly includes coprecipitation, hydrothermal, ion exchange, calcination recovery, and sol-gel methods. LDH-based materials have high anion exchange capacity, good thermal stability, and a large specific surface area, which can effectively adsorb and remove heavy metal ions, inorganic anions, organic pollutants, and oil pollutants from wastewater. Additionally, they are heterogeneous catalysts and have excellent catalytic effect in the Fenton system, persulfate-based advanced oxidation processes, and electrocatalytic system. This review ends with a discussion of the challenges and future trends of the application of LDHs in wastewater treatment.

Simple Rate Expression for Catalyzed Ammonia Decomposition for Fuel Cells

This paper examines NH3 decomposition rates based on a literature-proven six-step elementary catalytic (Ni-BaZrO3) mechanism valid for 1 × 105 Pa pressure in a 650-950 K range. The rates are generated using a hypothetical continuous stirred tank catalytic reactor model running the literature mechanism. Excellent correlations are then obtained by fitting these rates to a simple overall kinetic expression based on an assumed slow step, with the remaining steps in fast pseudo-equilibria. The robust overall simple rate expression is then successfully demonstrated in various packed bed reactor applications. This expression facilitates engineering calculations without the need for a complex, detailed mechanism solver package. The methodology used in this work is independent of the choice of catalyst. It relies on the availability of a previously published and validated elementary reaction mechanism.

Synthesis and Application of ZSM-5 Catalyst Supported with Zinc and/or Nickel in the Conversion of Pyrolytic Gases from Recycled Polypropylene and Polystyrene Mixtures under Hydrogen Atmosphere

Currently, catalytic pyrolysis has become a versatile and highly useful technology in the treatment of different plastic wastes. Thus, the development of selective catalysts to carry out cracking reactions and obtain a greater fraction of the desired products is essential. This study focuses on the synthesis of monometallic (Ni) and bimetallic (Ni-Zn) catalysts supported on ZSM-5 zeolite using an impregnation and co-impregnation method, respectively. The obtained catalysts were characterized by FTIR spectroscopy, N2 adsorption/desorption measurements, scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS), temperature programmed NH3 desorption (TPD-NH3) and thermogravimetric analysis (TGA). In this way, a mixture of polystyrene and polypropylene recycled with a catalyst/plastic waste ratio of 1:500 was used for pyrolysis tests. The best results were obtained using the Ni-Zn/ZSM-5 catalyst, which included better impregnation, increased surface acidity, decreased dispersion and a shorter reaction time in the catalytic pyrolysis process. Under the optimized conditions, catalytic pyrolysis showed an excellent performance to generate hydrocarbons of greater industrial interest.

Catalyst Design through Grafting of Diazonium Salts-A Critical Review on Catalyst Stability

In the pursuit of designing a reusable catalyst with enhanced catalytic activity, recent studies indicate that electrochemical grafting of diazonium salts is an efficient method of forming heterogeneous catalysts. The aim of this review is to assess the industrial applicability of diazonium-based catalysts with particular emphasis on their mechanical, chemical, and thermal stability. To this end, different approaches to catalyst production via diazonium salt chemistry have been compared, including the immobilization of catalysts by a chemical reaction with a diazonium moiety, the direct use of diazonium salts and nanoparticles as catalysts, the use of diazonium layers to modulate wettability of a carrier, as well as the possibility of transforming the catalyst into the corresponding diazonium salt. After providing descriptions of the most suitable carriers, the most common deactivation routes of catalysts have been discussed. Although diazonium-based catalysts are expected to exhibit good stability owing to the covalent bond created between a catalyst and a post-diazonium layer, this review indicates the paucity of studies that experimentally verify this hypothesis. Therefore, use of diazonium salts appears a promising approach in catalysts formation if more research efforts can focus on assessing their stability and long-term catalytic performance.

Palladated Cyclodextrin Nanosponge-Alginate Dual Bead as an Efficient Catalyst for Hydrogenation of Nitroarenes in Aqueous Solution

In this study, we present a novel composite material consisting of β-cyclodextrin nanosponge and sodium alginate, used as a support for the immobilization of palladium (Pd) nanoparticles. The composite alginate-cyclodextrin nanosponge beads were prepared, taking advantage of the 3D polymeric network and β-cyclodextrin cavity of the nanosponge. These beads exhibited excellent encapsulation capabilities for hydrophobic substrates, allowing their transfer in aqueous media. The cyclodextrin nanosponge served as a stabilizer for Pd nanoparticles and facilitated phase transfer. Additionally, the sodium alginate bead contributed to the robustness of the structure and improved the recovery and recyclability of the composite material. Comparative studies with control catalysts confirmed the beneficial effect of incorporating cyclodextrin nanosponge within alginate beads, particularly for more hydrophobic substrates. Optimization of reaction conditions revealed that employing 0.03 g of catalyst per mmol of nitroarene at 45 °C resulted in the maximum yield within 90 min. Evaluation of the substrate scope demonstrated the hydrogenation capability of various substrates with different electronic properties under the developed protocol. Notably, the nitro group was selectively reduced in substrates featuring competing functionalities. Furthermore, the recyclability and stability of the composite catalyst were confirmed, making it a promising candidate for sustainable catalysis.

The Atomic Observation of the Structural Change Process in Pt Networks in Air Using Environmental Cell Scanning Transmission Electron Microscopy

The structural change in Pt networks composed of multiple chain connections among grains was observed in air at 1 atm using atomic-resolution environmental cell scanning transmission electron microscopy. An aberration-corrected incident electron probe with a wide convergence angle made it possible to increase the depth resolution that contributes to enhancing the signal-to-noise ratio of Pt network samples in air in an environmental cell, resulting in the achievement of atomic-resolution imaging. The exposure of the Pt networks to gas molecules under Brownian motion, stimulated by electron beams in the air, increases the collision probability between gas molecules and Pt networks, and the Pt networks are more intensely stressed from all directions than in a situation without electron irradiation. By increasing the electron beam dose rate, the structural change of the Pt networks became significant. Dynamic observation on an atomic scale suggested that the structural change of the networks was not attributed to the surface atomic-diffusion-induced step motion but mainly caused by the movement and deformation of unstable grains and grain boundaries. The oxidized surface layers may be one of the factors hindering the surface atomic step motion, mitigating the change in the size of the grains and grain boundaries.

Coordination Compound (2,3,5-Triphenyltetrazolium)2[CuBr4] as Catalyst for the Curing Process of Epoxy Vinyl Ester Binders

This article presents a study on the synthesis and catalytic properties of copper complex (TPhTz)₂[CuBr₄] (here TPhTz is 2,3,5-triphenyltetrazolium). The obtained complex was characterized by various spectroscopic methods. The catalytic properties of the complex were evaluated in the curing of an epoxy vinyl ester system and their effectiveness was compared with that of cobalt octoate (its synonyms are known as Co(Oct)₂, cobalt(II) 2-ethylhexanoate, cobalt isocaprylate, etc.). The catalyst was added at an amount of 2 w.%. The results showed that a 8 w.% solution of the complex provides catalytic properties with an activation energy of 54.7 kJ/mol, which is 25.2 kJ/mol higher than a standard curing system with Co(Oct)₂. Thus, the solution of (TPhTz)₂[CuBr₄] in THF/DMSO accelerates the initiator decay process at room temperature, but for a longer time. The authors suggest that the curing mechanism may be accelerated by the appearance of (TPhTz)₂[Cu^IBr₃] and free bromine in the system. A strength test of fiberglass-reinforced plastic revealed that the addition of this complex did not lead to a decrease in flexural strength and hardness. Thus, use of the complex allowed for the production of polymer composite products using vacuum-assisted resin transfer molding where an extended injection time was needed.

Influences of the Reaction Temperature and Catalysts on the Pyrolysis Product Distribution of Lignocellulosic Biomass (Aspen Wood and Rice Husk)

It is important to clarify the distribution of pyrolysis products from lignocellulosic biomass for its thermal transformation to produce high-quality bio-oil. Influences of the reaction temperature and catalysts on the pyrolysis product distribution from aspen wood (AW) and rice husk (RH) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The difference in components from the lignocellulosic biomass results in different pyrolysis characteristics of the biomass raw materials. The reaction temperature significantly influences the product distribution from AW and RH pyrolysis. In all AW catalysis experiments, acids (8.35%), ketones (3.79%), phenols (4.73%), and esters (1.50%) have the lowest content while carbohydrates (48.75%) demonstrate the highest content when taking zinc chloride (ZnCl₂) as the catalyst; the HZSM-5 molecular sieve (HZSM-5) promotes the generation of esters (7.97%) and N-compounds (22.43%) while inhibiting production of aldehydes (2.41%); addition of an MCM-41 molecular sieve (MCM-41) is conducive to increasing the contents of aldehydes (21.29%), furans (5.88%), ketones (22.30%), acids (20.46%), and hydrocarbons (4.85%), while reducing the contents of alcohols (0) and carbohydrates (0). In all RH catalysis experiments, the addition of ZnCl₂ helps increase the content of carbohydrates (39.16%) and decrease the contents of ketones (3.89%), phenols (5.20%), alcohols (2.34%), esters (1.13%), and N-compounds (3.09%); when applying HZSM-5 as the catalyst, hydrocarbons (18.28%) and alcohols (6.66%) reach their highest content while acids (13.21%) have the lowest content; MCM-41 promotes the generation of aldehydes (25.33%) and furans (5.55%) while inhibiting that of carbohydrates (1.42%).

Recent Advances in Polycaprolactones for Anticancer Drug Delivery

Poly(ε-Caprolactone)s are biodegradable and biocompatible polyesters that have gained considerable attention for drug delivery applications due to their slow degradation and ease of functionalization. One of the significant advantages of polycaprolactone is its ability to attach various functionalities to its backbone, which is commonly accomplished through ring-opening polymerization (ROP) of functionalized caprolactone monomer. In this review, we aim to summarize some of the most recent advances in polycaprolactones and their potential application in drug delivery. We will discuss different types of polycaprolactone-based drug delivery systems and their behavior in response to different stimuli, their ability to target specific locations, morphology, as well as their drug loading and release capabilities.

Catalyzing Benzoxazine Polymerization with Titanium-Containing POSS to Reduce the Curing Temperature and Improve Thermal Stability

Trisilanolphenyl-polyhedral oligomeric silsesquioxane titanium (Ti-Ph-POSS) was synthesized through the corner-capping reaction, and Ti-Ph-POSS was dispersed in benzoxazine (BZ) to prepare Ti-Ph-POSS/PBZ composite materials. Ti-Ph-POSS could catalyze the ring-opening polymerization (ROP) of BZ and reduce the curing temperature of benzoxazine. In addition, Ti immobilized on the Ti-Ph-POSS cage could form covalent bonds with the N or O atoms on polybenzoxazine, improving the thermal stability of PBZ. The catalytic activity of the Ti-Ph-POSS/BZ mixtures was assessed and identified through ¹H nuclear magnetic resonance (¹H-NMR) and Fourier-transform infrared (FTIR) analyses, while thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were used to determine the thermal properties of the composite. It was found that PBZ exhibited a higher glass transition temperature (T_g) and better thermal stability when Ti-Ph-POSS was added. The curing behavior of the Ti-Ph-POSS/BZ mixtures showed that the initial (T_i) and peak (T_p) curing temperatures sharply decreased as the content of Ti-Ph-POSS and the heating rate increased. The curing kinetics of these Ti-Ph-POSS/BZ systems were analyzed using the Kissinger method, and the morphology of Ti-Ph-POSS/PBZ was determined via scanning electron microscopy (SEM). It was found that the Ti-Ph-POSS particles were well distributed in the composites. When the content exceeded 2 wt%, several Ti-Ph-POSS particles could not react with benzoxazine and were only dispersed within the PBZ matrix, resulting in aggregation of the Ti-Ph-POSS molecules.

The Removal of CH4 and NOx from Marine LNG Engine Exhaust by NTP Combined with Catalyst: A Review

Compared to diesel, liquefied natural gas (LNG), often used as an alternative fuel for marine engines, comes with significant advantages in reducing emissions of particulate matter (PM), SO_x, CO₂, and other pollutants. Promoting the use of LNG is of great significance for achieving carbon peaking and neutrality worldwide, as well as improving the energy structure. However, compared to diesel engines, medium- and high-speed marine LNG engines may produce higher methane (CH₄) emissions and also have nitrogen oxide (NO_x) emission issues. For the removal of CH₄ and NO_x from the exhaust of marine LNG engines, the traditional technical route of combining a methane oxidation catalyst (MOC) and an HN₃ selective catalytic reduction system (NH₃-SCR) will face problems, such as low conversion efficiency and high operation cost. In view of this, the technology of non-thermal plasma (NTP) combined with CH₄-SCR is proposed. However, the synergistic mechanism between NTP and catalysts is still unclear, which limits the optimization of an NTP-CH₄-SCR system. This article summarizes the synergistic mechanism of NTP and catalysts in the integrated treatment process of CH₄ and NO_x, including experimental analysis and numerical simulation. And the relevant impact parameters (such as electrode diameter, electrode shape, electrode material, and barrier material, etc.) of NTP reactor energy optimization are discussed. The work of this paper is of great significance for guiding the high-efficiency removal of CH₄ and NO_x for an NTP-CH₄-SCR system.

[Preparation of Catalyst Cyclodextrin-Fe-TAML to Activate H2O2 and Oxidize Organic Micropollutants in Water]

In order to improve the stability and catalytic activity of Fe-TAML, mono-6-oxy-cyclodextrin bonded Fe-TAML catalyst (CD-Fe-TAML) was prepared by bonding Fe-TAML with cyclodextrin (CD) through chlorosulfonylation reaction, metal chelation reaction, and nucleophilic substitution reaction. The catalytic activity and stability of CD-Fe-TAML and the oxidation degradation efficiencies of 34 organic micropollutants such as antibiotics and pesticides by activation of H₂O₂in water were studied. Compared with that of Fe-TAML, CD-Fe-TAML at pH 7.0 had a 49-fold and 25-fold increase in the rate of activating H₂O₂ to produce iron (Ⅴ/Ⅳ)-oxo intermediates and the degradation rate of the substrate, respectively, and its self-oxidation rate was reduced by 70%. The stability of CD-Fe-TAML was 0.7-699 times higher than that of Fe-TAML in the pH range of 3.0-10.0. Specifically, the stability of CD-Fe-TAML was 33-699 times higher than that of Fe-TAML in the pH range of 3.0-7.0. The sulfonic acid group in the molecular structure of CD-Fe-TAML had an electrophilic effect, which could increase the positive charge density of Fe in the active center, accelerate the O-O bond cleavage of H₂O₂ and the generation of iron(Ⅴ/Ⅳ)-oxo intermediates, improve the catalytic activity of Fe-TAML, and also improve its hydrolysis stability. Meanwhile, the CD group in the molecular structure had the "electron shuttle" effect and inclusion effect. The former could accelerate the electron transfer between the active center Fe-TAML and H₂O₂ to improve the catalytic activity of Fe-TAML. The latter could inhibit the hydrolysis and self-oxidation of the active center Fe-TAML by inclusion or binding of the hydrolysis sites and oxidation sites, thus improving its stability. The degradation efficiencies of micropollutants by CD-Fe-TAML/H₂O₂ under weakly acidic and neutral conditions (in the pH range of 5.0-7.0) were 0.4-59 times higher than those of Fe-TAML/H₂O₂. The degradation efficiencies of CD-Fe-TAML/H₂O₂ on nine micropollutants with a molar volume less than 0.20 L·mol^-1, such as acetamiprid and sulfadiazine, were 0.3-1.1 times higher than that of Fe-TAML/H₂O₂ at pH 8.0, and there were no significant differences between CD-Fe-TAML/H₂O₂ and Fe-TAML/H₂O₂for micropollutants with a molar volume greater than 0.20 L·mol^-1. The results of iodide oxidation by CD-Fe-TAML/H₂O₂ showed that I^- was not oxidized to produce iodo-disinfection byproducts (I-DBPs). The degradation of micropollutants by CD-Fe-TAML/H₂O₂ in the surface water sample was not disturbed by water components. The CD-Fe-TAML/H₂O₂ system has a potential application in the removal of organic micropollutants from water.

Iodine(V)-Based Oxidants in Oxidation Reactions

The chemistry of hypervalent iodine reagents has now become quite valuable due to the reactivity of these compounds under mild reaction conditions and their resemblance in chemical properties to transition metals. The environmentally friendly nature of these reagents makes them suitable for Green Chemistry. Reagents with a dual nature, such as iodine(III) reagents, are capable electrophiles, while iodine(V) reagents are known for their strong oxidant behavior. Various iodine(V) reagents including IBX and DMP have been used as oxidants in organic synthesis either in stoichiometric or in catalytic amounts. In this review article, we describe various oxidation reactions induced by iodine(V) reagents reported in the past decade.

Gold Nanoparticles AuNP Decorated on Fused Graphene-like Materials for Application in a Hydrogen Generation

The search for a sustainable, alternative fuel source to replace fossil fuels has led to an increased interest in hydrogen fuel. This combustible gas is not only clean-burning but can readily be produced via the hydrolysis of sodium borohydride. The main drawback of this reaction is that the reaction occurs relatively slowly and requires a catalyst to improve efficiency. This study explored a novel composite material made by combining gold nanoparticles and fused graphene-like materials (AuFGLM) as a catalyst for generating hydrogen via sodium borohydride. The novel fused graphene-like material (FGLM) was made with a sustainable dextrose solution and by using a pressure-processing method. Imaging techniques showed that FGLM appears to be an effective support template for nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize and determine the size, shape, and structure of nanoparticles and composites. The TEM study characterized the fused carbon backbone as it began to take on a rounder shape. The TEM images also revealed that the average diameter of the gold nanoparticle was roughly 23 nm. The FTIR study confirmed O-H, C-C, and C=O as functional groups in the materials. The EDS analysis showed that the composite contained approximately 6.3% gold by weight. The crystal structures of FGLM and AuFGLM were identified via P-XRD analysis. Various reaction conditions were used to test the catalytic ability of AuFGLM, including various solution pHs, temperatures, and doses of NaBH₄. It was observed that optimal reaction conditions included high temperature, an acidic solution pH, and a higher dose of NaBH₄. The activation energy of the reaction was determined to be 45.5 kJ mol^-1, and it was found that the catalyst could be used multiple times in a row with an increased volume of hydrogen produced in ensuing trials. The activation energy of this novel catalyst is competitive compared to similar catalysts and its ability to produce hydrogen over multiple uses makes the material an exciting choice for catalyzing the hydrolysis of NaBH₄ for use as a hydrogen fuel source.

Low temperature destruction of gas-phase per- and polyfluoroalkyl substances using an alumina-based catalyst

Per- and polyfluoroalkyl substances (PFAS) pose a major health and environmental problem. Methods are needed to ensure that PFAS are not released into the environment during their use or disposal. Alumina-based catalysts have been used for the abatement of small perfluorocarbons, e.g. tetrafluoromethane and perfluoropropane, emitted during the silicon etching process. Here, an alumina-based catalyst was tested to determine if these catalysts may facilitate the destruction of gas-phase PFAS. The catalyst was challenged with two nonionic surfactants with eight fluorinated carbons, 8:2 fluorotelomer alcohol and N-Ethyl-N-(2-hydroxyethyl)perfluorooctylsulfonamide. The catalyst helped decrease the temperatures needed for the destruction of the parent PFAS relative to a thermal-only treatment. Temperatures of 200°C were sufficient to destroy the parent PFAS using the catalyst, although a significant number of fluorinated products of incomplete destruction (PIDs) were observed. The PIDs were no longer observed by about 500°C with catalyst treatment. Alumina-based catalysts are a promising PFAS pollution control technology that could eliminate both perfluorocarbons and longer chain PFAS from gas streams.Implications: The release of per- and polyfluoroalkyl substances (PFAS) into the atmosphere can cause problems for human health and the environment. It is critical to reduce and eliminate PFAS emissions from potential sources, such as manufacturers, destruction technologies, and fluoropolymer processing and application sites. Here, an alumina-based catalyst was used to eliminate the emissions of two gas-phase PFAS with eight fully fluorinated carbons. No PFAS were observed in the emissions when the catalyst was at 500°C, lowering the energy requirements for PFAS destruction. This shows that alumina-based catalysts are a promising area for research for PFAS pollution controls and the elimination of PFAS emissions into the atmosphere.