Analysis of Homogeneous/Heterogeneous Reactions in an Electrohydrodynamic Environment Utilizing the Second Law

In this study, we investigate what happens to entropy in the presence of electrokinetic phenomena. It is speculated that the microchannel has an asymmetrical and slanted configuration. The presence of fluid friction, mixed convection, Joule heating, presence and absence of homogeneity, and a magnetic field are modelled mathematically. It is also emphasized that the diffusion factors of the autocatalyst and the reactants are equal. The governing flow equations are linearized using the Debye-Huckel and lubrication assumptions. The resulting nonlinear couple differential equations are solved using the program's integrated numerical solver, Mathematica. We take a graphical look at the results of homogeneous and heterogeneous reactions and talk about what we see. It has been demonstrated that homogeneous and heterogeneous reaction parameters affect concentration distribution f in different ways. The Eyring-Powell fluid parameters B1 and B2 display an opposite relation with the velocity, temperature, entropy generation number, and Bejan number. The mass Grashof number, the Joule heating parameter, and the viscous dissipation parameter all contribute to the overall increase in fluid temperature and entropy.

Solubilizing Metal-Organic Frameworks for an In Situ IR-SEC Study of a CO2 Reduction Catalyst

Metal-organic frameworks (MOFs) are typically assembled by bridging metal centers with organic linkers for various applications, including providing robust support for heterogeneous catalysts for CO2 reduction. In this study, we have demonstrated the solubilization of a MOF tethered to a CO2-reducing electrocatalyst and studied its fundamental electrochemistry in THF solvent using infrared spectroelectrochemistry (IR-SEC). The fundamental electrochemical properties of this immobilized catalyst were compared to that of its homogeneous counterpart. This approach provides a foundation for future experimental studies to bridge the gap between homogeneous and heterogeneous electrocatalysis.

Pathways towards achieving high current density water electrolysis: From material perspective to system configuration

Hydrogen is a clean, flexible, powerful energy vector that can be leveraged as a promising alternative to fossil fuels. Additionally, green hydrogen production has been recognized as one of the most prevalent solutions to decarbonize the energy system. Water electrolysis studies have increased throughout the decade as higher industrial interest comes into play. The catalyst, system design, and configuration act in a congenial manner to deliver high-performing water electrolysis. Despite performance targets peaking at high current densities, the current status of water electrolyzer technologies would require more research efforts to achieve such goals. This work presents a comprehensive review of how catalysts and electrolyzer designs can be enhanced to attain high current density water electrolysis. Modification strategies of catalysts, advances in characterization and modelling, and optimizing system designs are highlighted. Furthermore, this paper aims to elucidate the future research direction of water electrolysis to bridge the laboratory-to- industry gap.

Solar-Driven Thermocatalytic Synthesis of Octahydroquinazolinone Using Novel Polyvinylchloride (PVC)-Supported Aluminum Oxide (Al2O3) Catalysts

The chemical industry is one of the main fossil fuel consumers, so its reliance on sustainable and renewable resources such as wind and solar energy should be increased to protect the environment. Accordingly, solar-driven thermocatalytic synthesis of octahydroquinazolinone using polyvinylchloride (PVC)-supported aluminum oxide (Al2O3) as a catalyst under natural sunlight is proposed in this work. The Al2O3/PVC catalysts were characterized by FT-IR, SEM, BET, XRD, and XPS techniques. The obtained results indicate that the yield and reaction time can be modified by adjusting the molar ratio of the catalyst. To investigate the stability of the catalyst, the spent catalyst was reused in several reactions. The results indicated that, when a 50% Al2O3 catalyst is employed in an absolute solar heat, it performs exceptionally well in terms of yield (98%) and reaction time (35 min). Furthermore, the reaction times and yield of octahydroquinazolinone derivatives with an aryl moiety were superior to those of heteroaryl. All the synthesized compounds were well characterized by FT-IR, 1H-NMR, and 13C-NMR. The current work introduces a new strategy to use solar heat for energy-efficient chemical reactions using a cost-effective, recyclable environmentally friendly PVC/Al2O3 catalyst that produces a high yield.

Exploring the potential of Fe(III)-EGTA and Fe(III)-DTPA as the catalysts to enhance UV/persulfate in the degradation of aqueous sulfamethazine

The combination of UV and water-soluble Fe(III) complexes is an effective method for generating Fe(II) in situ for activating advanced oxidation processes. This study explored the potential of Fe(III)-diethylenetriaminepentaacetic acid (Fe(III)-DTPA) and Fe(III)-ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (Fe(III)-EGTA) in activating the UV/persulfate (UV/PS) for sulfamethazine removal. The initial screening showed that Fe(III)-EGTA and Fe(III)-DTPA could significantly improve the rate of sulfamethazine removal. The optimum molar ratios of persulfate to Fe(III)-DTPA and Fe(III)-EGTA were 100:1 and 100:2.5. The predicted percentage of sulfamethazine removal under the optimized conditions, obtained using response surface methodology, was ~99% for both catalysts. The pH range of 6 to 8 did not significantly affect the performance of UV/PS in the removal of sulfamethazine. The percentage sulfamethazine removal in the selected water samples was ranged from 93.6% to 99.6%, agreeing with the predicted value. The performance of both catalysts in activating UV/PS is comparable with that of the frequently used Fe(III)-EDDS. PRACTITIONERS POINTS: The potential of Fe(III)-DTPA and Fe(III)-EGTA in activating UV/persulfate (UV/PS) was explored. Fe(III)-DTPA and Fe(III)-EGTA improved the performance of UV/PS in sulfamethazine removal. Fe(III)-DTPA and Fe(III)-EGTA are effective in catalyzing UV/PS under pH 6 to 8. The performance of Fe(III)-DTPA and Fe(III)-EGTA is comparable with well-studied Fe(III)-EDDS.

Nanoshaped Cerium Oxide with Nickel as a Non-Noble Metal Catalyst for CO2 Thermochemical Reactions

Four different nanoshapes of cerium dioxide have been prepared (polycrystals, rods, cubes, and octahedra) and have been decorated with different metals (Ru, Pd, Au, Pt, Cu, and Ni) by incipient wetness impregnation (IWI) and ball milling (BM) methods. After an initial analysis based on oxygen consumption from CO₂ pulse chemisorption, Ni-like metal, and two forms of CeO₂ cubes and rods were selected for further research. Catalysts were characterized using the Brunauer-Emmett-Teller formula (BET), X-ray spectroscopy (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-visible spectrophotometry (UV-Vis), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (H₂-TPR) and CO₂ pulse chemisorption, and used to reduce of CO₂ into CO (CO₂ splitting). Adding metals to cerium dioxide enhanced the ability of CeO₂ to release oxygen and concomitant reactivity toward the reduction of CO₂. The effect of the metal precursor and concentration were evaluated. The highest CO₂ splitting value was achieved for 2% Ni/CeO₂-rods prepared by ball milling using Ni nitrate (412 µmol/g_cat) and the H₂ consumption (453.2 µmol/g_cat) confirms the good redox ability of this catalyst.

Recycling of Epoxy/Fiberglass Composite Using Supercritical Ethanol with (2,3,5-Triphenyltetrazolium)2[CuCl4] Complex

The widespread use of polymer composite materials (PCM) leads to an increase in non-recyclable waste. This paper discusses the feasibility of recycling fiberglass with an epoxy matrix by solvolysis in ethanol under supercritical conditions. The solvolysis process completes successfully within four hours in an environment of a pure solvent containing 10% water at a temperature of 280 °C when the solvent passes into the supercritical state. The treatment time increases up to 10 h at a process temperature of 250 °C. When using a coordination compound of copper(II) chloride with organic chloride salt having 2,3,5-triphenyltetrazolium as the counterion, having the composition of (2,3,5-triphenyltetrazolium)₂[CuCl₄], the treatment time is reduced. The addition of the complex of 5% by weight makes it possible to completely remove the epoxy matrix at a temperature of 250 °C for two hours. The products separated from the solvolysis liquid were studied by infrared spectroscopy. The resulting fibers were examined by thermogravimetric analysis and scanning electron microscopy. The residual strength of the recovered fibers is 98%. Thus, the resulting fibers can be reused in the composite industry. Including both for the production of decorative products and for the production of structural products made of polymer composite materials.

A Review on Catalytic Fast Co-Pyrolysis Using Analytical Py-GC/MS

Py-GC/MS combines pyrolysis with analytical tools of gas chromatography (GC) and mass spectrometry (MS) and is a quick and highly effective method to analyse the volatiles generated from small amounts of feeds. The review focuses on using zeolites and other catalysts in the fast co-pyrolysis of various feedstocks, including biomass wastes (plants and animals) and municipal waste materials, to improve the yield of specific volatile products. The utilisation of zeolite catalysts, including HZSM-5 and nMFI, results in a synergistic reduction of oxygen and an increase in the hydrocarbon content of pyrolysis products. The literature works also indicate HZSM-5 produced the most bio-oil and had the least coke deposition among the zeolites tested. Other catalysts, such as metals and metal oxides, and feedstocks that act as catalysts (self-catalysis), such as red mud and oil shale, are also discussed in the review. Combining catalysts, such as metal oxides and HZSM-5, further improves the yields of aromatics during co-pyrolysis. The review highlights the need for further research on the kinetics of the processes, optimisation of feed-to-catalyst ratios, and stability of catalysts and products.

Application of Silsesquioxanes in the Preparation of Polyolefin-Based Materials

This paper is a review of studies on the use of the polyhedral oligomeric silsesquioxanes (POSS) of various structures in the synthesis of polyolefins and the modification of their properties, namely: (1) components of organometallic catalytic systems for the polymerization of olefins, (2) comonomers in the copolymerization with ethylene, and (3) fillers in composites based on polyolefins. In addition, studies on the use of new silicon compounds, i.e., siloxane-silsesquioxane resins, as fillers for composites based on polyolefins are presented. The authors dedicate this paper to Professor Bogdan Marciniec on the occasion of his jubilee.

Platinum-Functionalized Graphene Oxide: One-Pot Synthesis and Application as an Electrocatalyst

This paper presents the preparation of platinum on a reduced graphene oxide matrix (PtrGO) using the microwave-assisted method with three different pH solutions. The platinum concentration determined by energy-dispersive X-ray analysis (EDX) was 4.32 (weight%), 2.16 (weight %) and 5.70 (weight%), corresponding to pH 3.3, 11.7 and 7.2, respectively. Pt functionalization of reduced graphene oxide (rGO) decreased the rGO specific surface, as shown by Brunauer, Emmett and Teller (BET) analysis. An XRD spectrum of platinum-decorated reduced graphene oxide (rGO) showed the presence of the associated phases of rGO and centered cubic platinum peaks. An oxygen reduction reaction (ORR) electrochemical characterization performed using the rotating disk electrode (RDE) method showed that in PtGO1 synthetized in an acidic environment, with 4.32 Pt (weight%) determined by EDX, platinum is much more dispersed, which explains its better electrochemical oxygen reduction reaction performance. Koutecky-Levich (K-L) plots calculated at different potentials prove a good linear relationship. Electron transfer numbers (n) determined from the K-L plots are between 3.1 and 3.8, which confirms that the ORR for all the samples can be regarded as first-order reaction kinetics of O₂ concentration formed on the Pt surface during ORR.

Theoretical-Experimental Study of the Action of Trace Amounts of Formaldehyde, Propionaldehyde, and Butyraldehyde as Inhibitors of the Ziegler-Natta Catalyst and the Synthesis of an Ethylene-Propylene Copolymer

The copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an inhibiting agent of the Ziegler-Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde, and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of -40.5, -47.22, -47.5, -5.2 and -1.3 kcal mol^-1 respectively.

Visualizing Catalytic Dynamics Process via Synchrotron Radiation Multi-Techniques

The importance of catalysts today as workhorses in most modern industrial fields cannot be downplayed. As a result, rational design and engineering of targeted catalysts have emerged as key objectives and are dependent on in-depth understanding of complex catalytic dynamics, such as phase transformation, structural reconstruction, electronic evolution, and differentiation in surface and bulk. The synchrotron radiation (SR) light sources with rich advanced experimental methods are being recognized as a comprehensive characterization platform, which could draw a full picture on such multiparameter-involved catalysis under actual working conditions. Herein, we summarize the recent progress of catalytic dynamics process studied by the means of various SR-techniques. In particular, the SR-based spectroscopic, scattering and imaging investigations on true catalysts are firstly introduced with the potential of in situ and operando characterizations. Apparently, the limitations from single SR-technique naturally prompt a simple combination of SR-techniques to better understand the whole catalysis process. Moreover, the discrepancies among various online testing facilities and batches of samples, along with random/systematic errors introduced by traditional intermittent/asynchronous measurement make it imperative to develop more prolific system, complementary of multiple SR-techniques for deep probing of dynamic catalytic processes from atomic, molecular and electronic levels. We believe that booming new light sources will further enrich the current multiple SR-techniques by offering more synchronous (Femto-microsecond time scale in the same experiment), fine (∼nm spatial resolution and ∼meV energy resolution) and real (actual atmosphere, pressure, temperature, etc.) catalytic conditions, and thus may realize the true visualization on future catalytic dynamic processes. This article is protected by copyright. All rights reserved.

Hydrogen Storage Performance of Mg/MgH2 and Its Improvement Measures: Research Progress and Trends

Due to its high hydrogen storage efficiency and safety, Mg/MgH₂ stands out from many solid hydrogen storage materials and is considered as one of the most promising solid hydrogen storage materials. However, thermodynamic/kinetic deficiencies of the performance of Mg/MgH₂ limit its practical applications for which a series of improvements have been carried out by scholars. This paper summarizes, analyzes and organizes the current research status of the hydrogen storage performance of Mg/MgH₂ and its improvement measures, discusses in detail the hot studies on improving the hydrogen storage performance of Mg/MgH₂ (improvement measures, such as alloying treatment, nano-treatment and catalyst doping), and focuses on the discussion and in-depth analysis of the catalytic effects and mechanisms of various metal-based catalysts on the kinetic and cyclic performance of Mg/MgH₂. Finally, the challenges and opportunities faced by Mg/MgH₂ are discussed, and strategies to improve its hydrogen storage performance are proposed to provide ideas and help for the next research in Mg/MgH₂ and the whole field of hydrogen storage.

Merging Platinum Single Atoms to Achieve Ultrahigh Mass Activity and Low Hydrogen Production Cost

Single atom catalysts (SACs) with isolated active sites exhibit the highest reported mass activity for hydrogen evolution catalysis, which is crucial for practical applications. Here, we demonstrate that ultrahigh mass activity can also be achieved by rationally merging the isolated platinum (Pt) active sites in SAC. The catalyst was obtained by the thermodynamically driven diffusing and merging phosphorus-doped carbon (PC) supported Pt single atoms (Pt₁@PC) into Pt nanoclusters (Pt_M@PC). X-ray absorption spectroscopy analysis revealed that the merged nanoclusters exhibit much stronger interactions with the support than the traditional method, enabling more efficient electron transfer. The optimized Pt_M@PC exhibited an order of magnitude higher mass activity (12.7 A mg_Pt^-1) than Pt₁@PC (0.9 A mg_Pt^-1) at an overpotential of 10 mV in acidic media, which is the highest record to date, far exceeding reports for other outstanding SACs. Theoretical study revealed that the collective active sites in Pt_M@PC exhibit both favorable hydrogen binding energy and fast reaction kinetics, leading to the significantly enhanced mass activity. Despite its low Pt content (2.2 wt %), a low hydrogen production cost of ∼3 USD kg^-1 was finally achieved in the full-water splitting at a laboratory scale.

Recent Advances in the Synthesis of 3,n-Fused Tricyclic Indole Skeletons via Palladium-Catalyzed Domino Reactions

3,n-fused (n = 4-7) tricyclic indoles are pervasive motifs, embedded in a variety of biologically active molecules and natural products. Thus, numerous catalytic methods have been developed for the synthesis of these skeletons over the past few decades. In particular, palladium-catalyzed transformations have received much attention in recent years. This review summarizes recent developments in the synthesis of these tricyclic indoles with palladium-catalyzed domino reactions and their applications in the total synthesis of representative natural products.

Performance of Cu/ZnO Nanosheets on Electrospun Al2O3 Nanofibers in CO2 Catalytic Hydrogenation to Methanol and Dimethyl Ether

The synthesis of methanol and dimethyl ether (DME) from carbon dioxide (CO₂) and green hydrogen (H₂) offers a sustainable pathway to convert CO₂ emissions into value-added products. This heterogeneous catalytic reaction often uses copper (Cu) catalysts due to their low cost compared with their noble metal analogs. Nevertheless, improving the activity and selectivity of these Cu catalysts for these products is highly desirable. In the present study, a new architecture of Cu- and Cu/Zn-based catalysts supported on electrospun alumina nanofibers were synthesized. The catalysts were tested under various reaction conditions using high-throughput equipment to highlight the role of the hierarchical fibrous structure on the reaction activity and selectivity. The Cu or Cu/ZnO formed a unique structure of nanosheets, covering the alumina fiber surface. This exceptional morphology provides a large surface area, up to ~300 m²/g, accessible for reaction. Maximal production of methanol (~1106 g_methanolKg_Cu^-1∙h^-1) and DME (760 g_DMEKg_Cu^-1∙h^-1) were obtained for catalysts containing 7% wt. Cu/Zn with a weight ratio of 2.3 Zn to Cu (at 300 °C, 50 bar). The promising results in CO₂ hydrogenation to methanol and DME obtained here point out the significant advantage of nanofiber-based catalysts in heterogeneous catalysis.

"Green" nZVI-Biochar as Fenton Catalyst: Perspective of Closing-the-Loop in Wastewater Treatment

In the framework of wastewater treatment plants, sewage sludge can be directed to biochar production, which when coupled with an external iron source has the potential to be used as a carbon-iron composite material for treating various organic pollutants in advanced oxidation processes. In this research, "green" synthesized nano zero-valent iron (nZVI) supported on sewage sludge-based biochar (BC)-nZVI-BC was used in the Fenton process for the degradation of the recalcitrant organic molecule. In this way, the circular economy principles were supported within wastewater treatment with immediate loop closing; unlike previous papers, where only the water treatment was assessed, the authors proposed a new approach to wastewater treatment, combining solutions for both water and sludge. The following phases were implemented: synthesis and characterization of nano zero-valent iron supported on sewage sludge-based biochar (nZVI-BC); optimization of organic pollutant removal (Reactive Blue 4 as the model pollutant) by nZVI-BC in the Fenton process, using a Definitive Screening Design (DSD) model; reuse of the obtained Fenton sludge, as an additional catalytic material, under previously optimized conditions; and assessment of the exhausted Fenton sludge's ability to be used as a source of nutrients. nZVI-BC was used in the Fenton treatment for the degradation of Reactive Blue 4-a model substance containing a complex and stable anthraquinone structure. The DSD model proposes a high dye-removal efficiency of 95.02% under the following optimal conditions: [RB4] = 50 mg/L, [nZVI] = 200 mg/L, [H₂O₂] = 10 mM. pH correction was not performed (pH = 3.2). Afterwards, the remaining Fenton sludge, which was thermally treated (named FS_treated), was applied as a heterogeneous catalyst under the same optimal conditions with a near-complete organic molecule degradation (99.56% ± 0.15). It could be clearly noticed that the cumulative amount of released nutrients significantly increased with the number of leaching experiments. The highest cumulative amounts of released K, Ca, Mg, Na, and P were therefore observed at the fifth leaching cycle (6.40, 1.66, 1.12, 0.62, 0.48 and 58.2 mg/g, respectively). According to the nutrient release and toxic metal content, FS_treated proved to be viable for agricultural applications; these findings illustrated that the "green" synthesis of nZVI-BC not only provides innovative and efficient Fenton catalysts, but also constitutes a novel approach for the utilization of sewage sludge, supporting overall process sustainability.

Formation of Metal-Oxide Nanocomposites with Highly Dispersed Co Particles from a Co-Zr Powder Blend by Mechanical Alloying and Hydrogen Treatment

The use of metal powders produced by mechanical treatment in various fields, such as catalysis or gas absorption, is often limited by the low specific surface area of the resulting particles. One of the possible solutions for increasing the particle fineness is hydrogen treatment; however, its effect on the structure of mechanically treated powders remains unexplored. In this work, for the first time, a metal-oxide nanocomposite powder was produced by mechanical alloying (MA) in a high-energy planetary ball mill from commercial powders of Zr and Co in the atomic ratio Co:Zr = 53:47 in an inert atmosphere, followed by high-pressure hydrogenation at room temperature. The initial powders and products of alloying and hydrogenation were studied by XRD, ⁵⁹Co Internal Field NMR, SEM, and HRTEM microscopy with EDX mapping, as well as Raman spectroscopy. MA resulted in significant amorphization of the powders, as well as extensive oxidation of zirconium by water according to the so-called "Fukushima effect". Moreover, an increase in hcp Co sites was observed. ⁵⁹Co IF NMR spectra revealed the formation of magnetically single-domain cobalt particles after hydrogenation. The crystallite sizes remained unchanged, which was not observed earlier. The pulverization of Co and an increase in hcp Co sites made this nanocomposite suitable for the synthesis of promising Fischer-Tropsch catalysts.

Synthesis and Properties of Ethylene/propylene and Ethylene/propylene/5-ethylidene-2-norbornene Copolymers Obtained on Rac-Et(2-MeInd)2ZrMe2/Isobutylaluminium Aryloxide Catalytic Systems

Ethylene/propylene (E/P) and ethylene/propylene/5-ethylidene-2-norbornene (E/P/ENB) copolymers were obtained on rac-Et(2-MeInd)₂ZrMe₂ activated by a number of isobutylaluminium aryloxides: (2,6-^tBu₂PhO-)AlⁱBu₂ (1-DTBP) (2,6-^tBu₂,4-Me-PhO-)AlⁱBu₂ (1-BHT), (2,4,6-^tBu₂PhO-)AlⁱBu₂ (1-TTBP), (2,6-^tBu₂,4-Me-PhO-)₂AlⁱBu (2-BHT), (2,6-^tBu₂PhO-)2AlⁱBu (2-DTBP), [(2-Me,6-^tBu-C₆H₃O)AlⁱBu₂]₂ (1-MTBP), [(2,6-Ph₂-PhO)AlⁱBu₂]₂ (1-DPP). This study shows how the structure of an activator influences catalytic activity and polymer properties, such as the copolymer composition, molecular weight characteristics, and thermophysical and mechanical properties. It has been shown that both the introduction of a bulky substituent in the para-position of the aryloxy group and the additional aryloxy group in the structure of an activator lead to a significant decrease in activity of the catalytic system in all studied copolymerization processes. Moreover, activation by bulkier aryloxides leads to lower levels of comonomer insertion and gives rise to higher molecular weight polymers. Broad or multiple endothermic peaks with different values of melting points are observed on the DSC curves of the copolymers obtained with different catalytic systems. The DSC of the thermally fractionated samples makes it possible to reveal the heterogeneity of the copolymer microstructure, which manifests itself in the presence of a set of lamellar crystallites of different thickness. The results also present the mechanical properties of the copolymers, such as the tensile strength (σ), elongation at break (ε), and engineering strain (EL). The synthesized E/P and E/P/ENB copolymers contain about 1-4 wt.% of the sterically hindered phenols obtained in situ as a residue of the hydrolyzed activators in the course of reaction quenching. This determines the increased thermooxidative stability of the copolymers.

Evaluation of Hydrogen Gettering Rates Correlated to Surface Composition and Texture of Nickel-Plated Zircaloy Getters of Different Heat Treatment Procedures

Coatings of metal specimens are known to have an impact on hydrogen gettering (hydrogen absorption). The coating can have one or more functions, such as enhancing gettering, preventing gettering and/or preventing oxidation of the metal substrate. It is known that contaminants and surface texture can impact hydrogen gettering/absorption performance, but has not previously been thoroughly explored. This study evaluated the role of different post-plating heat treatments of nickel-plated zircaloy-4 getters (NPGs) and the role of the heat treatments on gettering rates, surface composition and texture. Nickel plating is applied to prevent oxidation of the Zircaloy-4 surface and also enhances gettering. The nickel plating must be heat treated before desirable gettering can occur. Our NPG getters with historically known satisfying performance were pre-heat treated in air followed by activation heat treatment in a vacuum at a higher temperature. In this study, we were interested in finding out if both heat treatment steps were necessary to obtain a desirable gettering performance, or if one step could be omitted. XPS analysis showed that if the nickel surface is not heat treated before bonding the nickel to the zirconium in the activation step, there will be carbon contaminants on the surface, which significantly reduces gettering. We studied the texture of Zircaloy-4 using SEM/EBSD to compare NPGs with both heat treatment steps with NPGs that had no post-plating heat treatment to learn if the degree of cold work could be impacted by the heat treatment steps. We did not observe any differences in texture between them. We measured gettering rates of both pretreated and activated NPGs and NPGs that had been activated without first being pre-heat treated. We found that the NPGs without the first post-plating heating step had up to a seven times slower gettering rate and obtained higher plateau pressures due to the contaminated surface. Thus, the pre-heat treatment in air before activation is necessary to avoid slower gettering rates and higher plateau pressures.

Recent Advances in Structured Catalytic Materials Development for Conversion of Liquid Hydrocarbons into Synthesis Gas for Fuel Cell Power Generators

The paper considers the current state of research and development of composite structured catalysts for the oxidative conversion of liquid hydrocarbons into synthesis gas for fuel cell feeding and gives more detailed information about recent advances in the Boreskov Institute of Catalysis. The main factors affecting the progress of the target reaction and side reactions leading to catalyst deactivation are discussed. The properties of the Rh/Ce_0.75Zr_0.25O₂/Al₂O₃/FeCrAl composite multifunctional catalyst for the conversion of diesel fuel into synthesis gas are described. The results of the catalyst testing and mathematical modeling of the process of diesel fuel steam-air conversion into synthesis gas are reported.

Changes in the Electrophysical Parameters of Nanomodified Elastomers Caused by Electric Current's Passage

The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements' manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, as this expands the possibilities of such materials' application. Elastomers based on silicon-organic compounds and polyurethane modified with multi-walled carbon nanotubes (MWCNTs) were studied at various concentrations of Ni/MgO or Co-Mo/MgO and voltages (220, 250, and 300 V). It was found that an increase in voltage from 220 to 300 V leads to an initial increase in specific power on one-third followed by a subsequent decrease in a specific power when switched on again to 220 V (for -40 °C) of up to ~44%. In turn, for a polyurethane matrix, an increase in voltage to 300 V leads to an initial peak power value of ~15% and a decrease in power when switched on again by 220 V (for -40 °C) to ~36% (Ni/MgO -MWCNT). The conducted studies have shown that the use of a polyurethane matrix reduces power degradation (associated with voltage surges above 220 V) by 2.59% for Ni/MgO-based MWCNT and by 10.42% for Co-Mo/MgO. This is due to the better heat resistance of polyurethane and the structural features of the polymer and the MWCNT. The current studies allow us to take the next step in the development of functional materials for electric heating and demonstrate the safety of using heaters at a higher voltage of up to 300 V, which does not lead to their ignition, but only causes changes in electrophysical parameters.

On the Catalytic Performance of (ZrO)n (n=1-4) Clusters for CO Oxidation: A DFT Study

The unique characteristic of superatoms to show chemical properties like those of individual atoms opens a new avenue towards replacing noble metals as catalysts. Given the similar electronic structures of the ZrO superatom and the Pd atom, the CO oxidation mechanisms catalysed by (ZrO)_n (n=1-4) clusters were investigated in detail to evaluate their catalytic performance. Our results reveal that a single ZrO superatom exhibits superior catalytic ability in CO oxidation than both larger (ZrO)_n (n=2-4) clusters and a Pd atom, indicating the promising potential of ZrO as a "single-superatom catalyst". Moreover, the mechanism of CO oxidation catalysed by ZrO^+/- suggests that depositing a ZrO superatom onto the electron-rich substrates is a better choice for practical catalysis application. Accordingly, a graphene nanosheet (coronene) was chosen as a representative substrate for ZrO and Pd to assess their catalytic performances in CO oxidation. Acting as an "electron sponge", this carbon substrate can both donate and accept charges in different reaction steps, enabling the supported ZrO to achieve enhanced catalytic performance in this process with a low energy barrier of 19.63 kcal/mol. This paper presents a new realization on the catalytic performance of Pd-like superatom in CO oxidation, which could increase the interests in exploring noble metal-like superatoms as efficient catalysts for various reactions.

Synthesis of Nickel and Cobalt Ferrite-Doped Graphene as Efficient Catalysts for Improving the Hydrogen Storage Kinetics of Lithium Borohydride

Featuring a high hydrogen storage content of up to 20 wt%, complex metal borohydrides remain promising solid state hydrogen storage materials, with the real prospect of reversible behavior for a zero-emission economy. However, the thermodynamic barriers and sluggish kinetics are still barriers to overcome. In this context, nanoconfinement has provided a reliable method to improve the behavior of hydrogen storage materials. The present work describes the thermodynamic and kinetic enhancements of LiBH₄ nanoconfined in MFe₂O₄ (M=Co, Ni) ferrite-catalyzed graphene host. Composites of LiBH₄-catalysts were prepared by melt infiltration and investigated by X-ray diffraction, TEM, STEM-EDS and TPD. The role of ferrite additives, metal precursor treatment (Ar, Ar/H₂) and the effect on hydrogen storage parameters are discussed. The thermodynamic parameters for the most promising composite LiBH₄-graphene-NiFe₂O₄ (Ar) were investigated by Kissinger plot method, revealing an E_A = 127 kJ/mol, significantly lower than that of neat LiBH₄ (170 kJ/mol). The reversible H₂ content of LiBH₄-graphene-NiFe₂O₄ (Ar) after 5 a/d cycles was ~6.14 wt%, in line with DOE's target of 5.5 wt% storage capacity, while exhibiting the lowest desorption temperature peak of 349 °C. The composites with catalysts treated in Ar have lower desorption temperature due to better catalyst dispersion than using H₂/Ar.

Toluene oxidation removal from air over CoxOy/AC catalyst

The Co_xO_y/AC catalysts were prepared by wet impregnation method for toluene oxidation removal from air. The thermal stability of cobalt nitrate and Co oxide on the activated carbon (AC) support surface was analysed by thermal analysis. The physicochemical properties of the prepared catalysts were characterised by XRD, SEM, H₂-TPR, and XPS. AC support with high specific surface area and developed pore structure can promote the dispersion of Co species on its surface to form highly dispersed Co oxide species. The participation of AC supports can promote the partial reduction of Co₃O₄ species to CoO species to coexist in the prepared Co_xO_y/AC catalyst. The Co²⁺/Co³⁺ ratio was significantly affected by the calcination temperature, and the appropriate Co²⁺/Co³⁺ ion pairs in the studied Co_xO_y/AC catalyst is helpful to the activity of O₂ molecules to form reactive oxygen species. The oxygen species composition on the catalyst surface is obviously affected by the calcination temperature, which plays an important role in toluene oxidation reaction. The studied Co_xO_y/AC catalysts exhibited excellent toluene oxidation removal performances. The conversion of toluene exceeded 97% and 99% at 240°C and 250°C, respectively, and maintained good stability within 700 min. That is to say, the concentration of toluene in the air can be reduced from 10,000 ppm to less than 40 ppm by using the Co_xO_y/AC catalyst.