Mn nanoparticles encapsulated within mesoporous helical n-doped carbon nanotubes as highly active air cathode for zinc–air batterie

The practical application of clean energy conversion and storage technologies, such as fuel cells and metal–air batteries, have been significantly impeded by the high cost and scarcity of precious metal catalysts used for the oxygen reduction reaction (ORR). Transitional metal/carbon compounds are a promising alternative to precious metal catalysts for the OR

The effect of humidity on the operation of wooden beams of a composite section on compliant couplings without the use of glue

In wooden structures, the change in humidity affects the deformability and load-carrying capacity of joints and structures according to the criteria of the first and second groups of limiting states. In wooden beams of the composite cross-section on mechanical connections, with an increase in the moisture content of the timber, the structural strength of the structures is affected both by the increment in the deformations of the joints and by the change in the physical and mechanical characteristics of the wood, primarily the modulus of elasticity of the material

Membrane supports designed for Pd membranes

Unique properties such as high permeance and a theoretically infinite selectivity to hydrogen gas exhibited by Palladium (Pd)-based membranes have caused thin Palladium films to emerge as an attractive method to separate and purify hydrogen from syngas. Pd-based membrane costs are a considerable economic hindrance to transforming this technology into a commonly applied gas separation technology, hence, the cost of these membranes needs to be reduced significantly. Cost reduction can be achieved by utilising composite membranes, composed of a thin dense layer of a Pd alloy deposited onto a porous support structure. While significant research has focused on Pd-based top layer optimisation, the physical properties of each sublayer have all but been ignored. In order to address challenges such as stability and durability of membranes, membrane production and operation costs more effectively, the current work aims to look at each layer as an integral part of the membrane system instead of unlinked individual layers. The end product of Pd-based membrane development should exhibit the following characteristics; a) defect-free continuous films, without protruding defects which would negatively affect the quality of the collected permeate gas, b) mechanically and chemically stable films, to hinder the formation of defects during the lifetime of the membrane under operating conditions, c) the film should have minimum thickness required in order to obtain a) and b) as excessive thickness will have a detrimental impact on H2 permeance and material cost. Please click Additional Files below to see the full abstract

Synthesis, characterisation and evaluation of IrO2 based binary metal oxide electrocatalysts for oxygen evolution reaction

IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (1 ≥ x ≥ 0.7) were synthesized, characterised and evaluated as electrocatalysts for the oxygen evolution reaction in solid polymer electrolyte electrolysers. The electrocatalysts were synthesised by adapting the Adams fusion method. The physical properties of the electrocatalysts were characterised by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. Electrochemical activity of the electrocatalysts toward the oxygen evolution reaction was evaluated by cyclic voltammetry and chronoamperometry. X-ray diffraction revealed no phase separation when RuO2 or SnO2 was introduced into the IrO2 lattice suggesting that solid solutions were formed. Transmission electron microscope analysis revealed nanosize particles for all synthesised metal oxides. Crystallinity increased with the addition of RuO2 and SnO2 while a suppression of crystal growth was observed with the addition of Ta2O5 to IrO2. Chronoamperometry revealed that the addition of all the secondary metal oxides to IrO2 resulted in improved catalytic performance. Ir0.7Ru0.3O2 was identified as the most promising electrocatalyst for the oxygen evolution reaction. Keywords:Web of Scienc

Optimization of gas diffusion electrode for polybenzimidazole-based high temperature proton exchange membrane fuel cell: Evaluation of polymer binders in catalyst layer

Gas diffusion electrodes (GDEs) prepared with various polymer binders in their catalyst layers (CLs) were investigated to optimize the performance of phosphoric acid doped polybenzimidazole (PBI)-based high temperature proton exchange membrane fuel cells (HT-PEMFCs). The properties of these binders in the CLs were evaluated by structure characterization, electrochemical analysis, single cell polarization and durability test. The results showed that polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF) are more attractive as CL binders than conventional PBI or Nafion binder. At ambient pressure and 160 o C, the maximum power density can reach w 0.61 W cm-2 (PTFE GDE), and the current density at 0.6 V is up to ca. 0.52 A cm-2 (PVDF GDE), with H2/air and a platinum loading of 0.5 mg cm-2 on these electrodes. Also, both GDEs showed good stability for fuel cell operation in a short term durability test.Web of Scienc

Palygorskite hybridized carbon nanocomposite as a high-performance electrocatalyst support for formic acid oxidation

A nanocomposite, in which acid-treated palygorskite was hybridized with carbon, was prepared and designed as an efficient support for electrocatatlysts. Pd nanoparticles were deposited on the hybrid support as an electrocatalyst for formic acid oxidation. The hybrid supports and electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).TEMandXRDresults showed that acid treatment had an effective impact on the morphology of palygorskite, but did not destroy its architecture. XPS results indicated that the introduction of palygorskite resulted in a negative shift of binding energy of Pd deposited on it. The electrochemical results showed that the addition of palygorskite into the carbon facilitated the formation ofOHads orOads on the surface of Pd/C-PLS, and further improved the formic acid electrooxidation activity. Therefore, considerable improvements in electrocatalytic activity toward formic acid oxidation was achieved by using this hybrid support when compared with conventional carbon support, suggesting that the introduction of SiO2-based porous palygoriskite was an excellent and cost-efficient way to improve the electrocatalytic performance of carbon support.Web of Scienc

Highly-dispersed vanadium nitride supported on porous nitrogen-doped carbon material as a high-performance cathode for lithium-sulfur batteries

Transition metals and their compounds supported on carbon materials are widely used as cathodes for lithium-sulfur batteries. Vanadium nitride is considered to be a promising cathode because of its good adsorption capacity for lithium polysulfides and high catalytic activity, but in practice it usually shows insufficient electrical conductivity and low electrocatalytic activity due to particles agglomeration. In this study, highly dispersed vanadium nitride supported on porous nitrogen-doped carbon was prepared via one-pot pyrolysis in a molten salt medium. Physical characterization revealed VN particles with a uniform size distribution of ca. 10 nm well dispersed on the carbon surface. When used as a cathode for Li−S battery, the material delivered a specific discharge capacity of 1050 mAh g−1 at 0.2 C and good rate performance. During the stability test over 500 continuous cycles, the average decay rate was 0.059 % per cycle. The study demonstrates prospective application of the newly developed electrocatalytic material as a cathode in lithium-sulfur batteries

Ex-situ electrochemical characterization of iro2 synthesized by a modified Adams fusion method for the oxygen evolution reaction

The development of highly stable and active electrocatalysts for the oxygen evolution reaction (OER) has attracted significant research interest. IrO2 is known to show good stability during the OER however it is not known to be the most active. Thus, significant research has been dedicated to enhance the activity of IrO2 toward the OER. In this study, IrO2 catalysts were synthesized using a modified Adams fusion method. The Adams fusion method is simple and is shown to directly produce nano-sized metal oxides. The effect of the Ir precursor salt to the NaNO3 ratio and the fusion temperature on the OER activity of the synthesized IrO2 electrocatalysts, was investigated. The OER activity and durability of the IrO2 electrocatalysts were evaluated ex-situ via cyclic voltammetry (CV), chronopotentiometry (CP), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV)

The effect of PtRuIr nanoparticle crystallinity in electrocatalytic methanol oxidation

Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate