Production of WE43 magnesium alloy by powder metallurgy and the effect of glucose on wear resistance in biocorrosive wear

In this study, WE43 magnesium alloy was produced by the powder metallurgy method. Microstructural analyses of the produced samples were carried out using the scanning electron microscopy method. X-ray fluorescence, energy dispersive x-ray (EDS) analysis, and hardness tests were also implemented to investigate the physical and chemical properties of the alloys. The volumetric hardness was measured to be approximately 53 HV. The microstructural analysis and EDS results indicated the presence of Mg24Y5 and Mg41Nd5 phases in the alloys. Reciprocating-type experiments were carried out in dry and corrosive environments to evaluate the wear resistance. Hanks’s solution containing 2% g/l glucose was used as the corrosive environment. Gluconic acid resulting from the oxidation of glucose in the Hanks’s solution formed a new thin layer on the alloy surface, which was observed in the worn surface images. The formation of the thin film on the alloy surface resulted in an increase in wear resistance by 37%. The results unraveled the potential of the WE43 alloys as implant materials in areas in contact with glucose.

Cobalt catalysts (Co–N–C) for C–O bond cleavage in lignin-derived aryl ethers and lignin

The transformation of lignin into value-added chemicals represents one of the relevant approaches for sustainable development.

A Hands-on Guide to the Synthesis of High-Purity and High-Surface-Area Magnesium Oxide

In this study, magnesium nitrate, chloride or sulphate were used in the synthesis of Mg(OH)2, the precursor of MgO. It was found that the counter ion strongly influences the purity of the Mg(OH)2, as well as the specific surface area of the obtained MgO. The latter is also strongly influenced by the calcination temperature. The choice of the precipitating agent can lead to the introduction of K+ or Na+ ions and hence NH3 (aq) is the best choice. A multistep precipitation procedure of Mg(OH)2 was proposed to lower the concentration of typical impurities (Fe, Ni and Mn) found in commercial p.a. purity Mg(NO3)2. The effect of the number of portions of water used for washing of Mg(OH)2 on the purity of the final product has also been investigated in detail. The stages of formation of grains of Mg(OH)2 and their subsequent thermal decomposition was described together with determination of the introduction of new impurities into the material. Large scale (1500 g) preparation of Mg(OH)2 with an improved purity was performed and described. Therefore, this study explains what measures should be taken to obtain pure magnesia catalysts and is a valuable resource for catalytic research in which magnesia is used.

Pyrolysis gas from biomass and plastics over X-Mo@MgO (X = Ni, Fe, Co) catalysts into functional carbon nanocomposite: Gas reforming reaction and proper process mechanisms

The metal catalysts X-Mo@MgO (X = Ni, Fe, Co) was studied as excellent catalyst for catalytic pyrolysis conversion of biomass and plastics into functional carbon nanocomposite. The proper reaction mechanism of the process was explored through the gas composition, and explored the bactericidal performance of functional carbon nanocomposite. The results showed that the Ni, Fe and Co-based catalysts elevated H₂ gas yield reached to 57%, 34% and 44% as the addition of Mo, due to Mo or its oxide species for scission of small molecule compound. The introduction of NiMo@MgO catalyst produced lower CH₄, and higher H₂ and MWCNTs, which indicated that the formation of MWCNTs is mainly attributed to CH₄ dehydrogenation. As a comparison, FeMo@MgO catalyst for CO disproportionation reaction could generate more MWCNTs and lower H₂. The functional carbon nanocomposite from FeMo@MgO catalyst were comprehensively evaluated by multiple characterizations. TPO and Raman results confirmed that FeMo@MgO catalyst can provide an excellent carrier to generate MWCNTs with few defects and high graphitization. The functional carbon nanocomposite were initially applied to E.coli extinguishing. The core-shell structure catalyst not only has excellent bactericidal performance, but also has strong resistance to metal leaching.

Morphology Design and Fabrication of Bio-Inspired Nano-MgO-Mg(OH)2 via Vapor Steaming to Enable Bulk CO2 Diffusion and Capture

The absorption of CO₂ on MgO is being studied in depth in order to enhance carbon engineering. Production of carbonate on MgO surfaces, such as MgCO₃, for example, has been shown to hinder further carbon lattice transit and lower CO₂ collecting efficiency. To avoid the carbonate blocking effect, we mimic the water harvesting nano-surface systems of desert beetles, which use alternate hydrophobic and hydrophilic surface domains to collect liquid water and convey condensed droplets down to their mouths, respectively. We made CO₂-philic MgO and CO₂-phobic Mg(OH)₂ nanocomposites from electrospun nano-MgO by vapor steaming for 2-20 min at 100 °C. The crystal structure, morphology, and surface properties of the produced samples were instrumentally characterized using XRD, SEM, XPS, BET, and TGA. We observed that (1) fiber morphology shifted from hierarchical particle and sheet-like structures to flower-like structures, and (2) CO₂ capture capacity shifted by around 25%. As a result, the carbonate production and breakdown processes may be managed and improved using vapor steaming technology. These findings point to a new CO₂ absorption technique and technology that might pave the way for more CO₂ capture, mineralization, and fuel synthesis options.

Synthesis, photocatalytic and antibacterial activities of a PDS-activated MgO nanocatalyst: experimental and theoretical studies

PDS activation of MgO nanoparticles provides the opportunity to explore their applications and activities.

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

Catalysis is essential to modern life and has a huge economic impact. The development of new catalysts critically depends on synthetic methods that enable the preparation of tailored nanomaterials. Pulsed laser in liquids synthesis can produce uniform, multicomponent, nonequilibrium nanomaterials with independently and precisely controlled properties, such as size, composition, morphology, defect density, and atomistic structure within the nanoparticle and at its surface. We cover the fundamentals, unique advantages, challenges, and experimental solutions of this powerful technique and review the state-of-the-art of laser-made electrocatalysts for water oxidation, oxygen reduction, hydrogen evolution, nitrogen reduction, carbon dioxide reduction, and organic oxidations, followed by laser-made nanomaterials for light-driven catalytic processes and heterogeneous catalysis of thermochemical processes. We also highlight laser-synthesized nanomaterials for which proposed catalytic applications exist. This review provides a practical guide to how the catalysis community can capitalize on pulsed laser in liquids synthesis to advance catalyst development, by leveraging the synergies of two fields of intensive research.

Segregation Engineering in MgO Nanoparticle-Derived Ceramics: The Impact of Calcium and Barium Admixtures on the Microstructure and Light Emission Properties

Nanostructured segregates of alkaline earth oxides exhibit bright photoluminescence emission and great potential as components of earth-abundant inorganic phosphors. We evaluated segregation engineering of Ca²⁺- and Ba²⁺-admixtures in sintered MgO nanocube-derived compacts. Compaction and sintering transform the nanoparticle agglomerates into ceramics with residual porosities of Φ = 24-28%. Size mismatch drives admixture segregation into the intergranular region, where they form thin metal oxide films and inclusions decorating grain boundaries and pores. An important trend in the median grain size evolution of the sintered bodies with d_{Ca(10 at. %)} = 90 nm < d_{Ba(1 at. %)} = 160 nm < d_MgO = 250 nm ∼ d_{Ca(1 at. %)} = 280 nm < d_{Ba(10 at. %)} = 870 nm is rationalized by segregation and interface energies, barriers for ion diffusion, admixture concentration, and the increasing surface basicity of the grains during processing. We outline the potential of admixtures on interface engineering in MgO nanocrystal-derived ceramics and demonstrate that in the sintered compacts, the photoluminescence emission originating from the grain surfaces is retained. Interior parts of the ceramic, which are accessible to molecules from the gas phase, contribute with oxygen partial pressure-dependent intensities to light emission.

The influence of support materials on the structural and electronic properties of gold nanoparticles – a DFT study

This study investigates the effect of commonly used support materials (MgO, C, CeO₂) on small gold particles using dispersion corrected density functional theory (DFT-D).

Understanding the performance and mechanism of Mg-containing oxides as support catalysts in the thermal dry reforming of methane

Dry reforming of methane (DRM) is one of the more promising methods for syngas (synthetic gas) production and co-utilization of methane and carbon dioxide, which are the main greenhouse gases. Magnesium is commonly applied in a Ni-based catalyst in DRM to improve catalyst performance and inhibit carbon deposition. The aim of this review is to gain better insight into recent developments on the use of Mg as a support or promoter for DRM catalysts. Its high basicity and high thermal stability make Mg suitable for introduction into the highly endothermic reaction of DRM. The introduction of Mg as a support or promoter for Ni-based catalysts allows for good metal dispersion on the catalyst surface, which consequently facilitates high catalytic activity and low catalyst deactivation. The mechanism of DRM and carbon formation and reduction are reviewed. This work further explores how different constraints, such as the synthesis method, metal loading, pretreatment, and operating conditions, influence the dry reforming reactions and product yields. In this review, different strategies for enhancing catalytic activity and the effect of metal dispersion on Mg-containing oxide catalysts are highlighted.

Green synthesis of a Cu/MgO nanocomposite by Cassytha filiformis L. extract and investigation of its catalytic activity in the reduction of methylene blue, congo red and nitro compounds in aqueous media

This work reports the green synthesis of a Cu/MgO nanocomposite using Cassytha filiformis L. extract as a reducing agent without stabilizers or surfactants.

Fabrication of MgO–rGO hybrid catalysts with a sandwich structure for enhanced ethylbenzene dehydrogenation performance

MgO–rGO hybrid catalysts with a sandwich structure have been successfully prepared and show obviously boosted reactivity in the direct dehydrogenation of ethylbenzene.

Recent progress in the synthesis of nanostructured magnesium hydroxide

This highlight discusses magnesium hydroxide design at the nanoscale, common aspects of crystallite growth and how nanostructuring impacts properties.