Methanol electrooxidation on synthesized PtRu nanocatalyst supported on acetylene black in half cell and in direct methanol fuel cell

We reported the direct reduction of H₂PtCl₆ and RuCl₃ solution containing acetylene black powder by Na₂S₂O₄ to make Pt–Ru (20–10 wt%) supported on acetylene black (Pt–Ru/AB) as a nanocatalyst for methanol electrooxidation in acidic media. The electrochemical activity of catalyst was studied by electrochemical impedance spectroscopy, linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Structural aspects of the Pt–Ru (20–10 wt%)/AB were studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The analysis of electrochemical results indicated lower charge transfer resistance, higher peak current for Pt–Ru (20–10 wt%)/AB compared to the commercial catalyst, Pt–Ru (20–10 wt%)/carbon Vulcan. XRD spectra verified a face centered cubic structure for the synthesized Pt–Ru/AB and its particle size was mostly 10 nm according to TEM and XRD images. In DMFC, Pt–Ru/AB had superior performance compared to the commercial catalyst in all current densities, which could be attributed to enhancement of the methanol oxidation kinetics, higher conductivity, and more uniform distribution of the ionomer in anode catalyst layer.     

Effect of polyaniline-doped trifluoromethane sulfonic acid nanofiber composite film thickness on electrode for methanol oxidation

Three different electrodes containing polyaniline (PANI) and platinum (Pt) nanoparticles were fabricated. Polyaniline was coated onto TGPO60-T by carrying out the electropolymerization of aniline and trifluoromethane sulfonic acid as the proton-conductive monomer, and platinum was electroreduced onto the carbon paper based electrodes (with or without polyaniline) that are used in direct methanol fuel cells (DMFCs).The efficiencies of these electrodes in methanol oxidation were examined and their electrochemical properties were investigated with cyclic voltammetry, chronoamperometry, linear sweep voltammetry, and electrochemical impedance spectroscopy. The surface morphologies of the electrodes were characterized by using scanning electron microscopy. The electro-oxidation reaction on the Pt-PANI/carbon paper catalyst with a thick layer of polyaniline has a much lower activation energy than on the Pt/carbon paper catalyst and on the Pt-PANI/carbon paper catalyst with a thin layer of polyaniline. Our results also show that the electrode with a thick polyaniline layer is more efficient than the electrodes with a thin polyaniline layer or without polyaniline.     

Effect of Oxide Bifilms on the Fracture Behavior of AM60B Mg Alloy

Transactions of the Indian Institute of Metals - The effect of entrained Mg oxide bifilms on the tensile properties and fracture behavior of AM60B Mg alloy was studied. For this purpose, tensile...     

Investigation on beneficial effects of beryllium on entrained oxide films,mechanical properties and casting reliability of Fe-rich Al–Si cast alloy

The microstructure and tensile properties of cast Al–9·5Si–0·35Mg alloy containing 1·5 wt-%Fe have been studied to investigate the potential influence of beryllium (Be) on the entrained oxide films and its effects on the precipitation of Fe-rich phases from liquid metal. It was found that addition of Be has a great influence on the microstructure and reliability of the cast alloy. Beryllium changes the platelet morphology of Fe-rich phases to less harmful shapes. Meanwhile, this element reduces the entrainment of the double oxide films into the melt probably due to its effect on changing the strength of surface oxides in a manner that resists tearing. These effects, in turn, lead to an increase in mechanical properties and casting reliability of the alloy.     

Comparative Study of On‐Line Membrane Electrode Assembly Activation Procedures in Proton Exchange Membrane Fuel Cell

The major objectives of this study are to identify the best activation procedure between commonly used procedures that can significantly reduce the conditioning duration and to understand the change in interfacial properties during conditioning. In order to do that, three on‐line activation procedures were employed for activating of identical MEAs in PEMFC and studied by polarization curve and electrochemical impedance spectroscopy (EIS). These methods are constant current (0.25 A cm^–2) for 19 h, constant voltage (0.6 V) for 9 h, and USFCC protocol. The best performance was achieved by USFCC protocol within 15 h, but by constant voltage procedure, 96% of mentioned protocol was obtained during 6 h. So constant voltage activation proceeded remarkably fast, and most of the activation process was achieved in the first few hours. Obtained results from Nyquist plots during/after MEA conditioning indicate mentioned process are irreversible and interfacial structures of MEAs are different even after finishing of MEA break‐in. It could be affected the MEA performance and even its durability. These results are consistence with the obtained performance of activated MEAs either in H₂/air or H₂/O₂ PEMFC. We found the mentioned constant current procedure consume long time without reaching to expectable performance even after 19 h.     

Effect of Partial Substitution of Mn for Ni on Mechanical Properties of Friction Stir Processed Hypoeutectic Al-Ni Alloys

In this study, the mechanical properties of as-cast and FSPed Al-2Ni-xMn alloys (x?=?1, 2, and 4 wt pct) were investigated and compared with those of the as-cast and FSPed Al-4Ni alloy. According to the results, the substitution of 2 wt pct Mn for 2 wt pct Ni leads to the formation of fine Mn-rich intermetallics in the microstructure increasing the tensile strength, microhardness, fracture toughness, and specific strength of alloy by 22, 56, 45, and 35 pct, respectively. At higher Mn concentrations, the formation of large Mn-rich platelets in the microstructure reduces the tensile properties. Friction stir processing at 12 mm/min and 1600 rpm significantly enhances both the strength and ductility of the alloy. The tensile strength, yield strength, fracture strain, fracture toughness, microhardness, and specific strength of FSPed Al-2Ni-4Mn alloy improved by 97, 83, 30, 380, 152, and 110  pct, respectively, as compared to those of the as-cast Al-4Ni alloy. This can be attributed to dispersion strengthening of Ni- and Mn-rich dispersoids, formation of ultrafine grains, and elimination of casting defects. The fractography results also show that the brittle fracture mode of the as-cast Mn-rich alloys turns to a more ductile mode, comprising fine and equiaxed dimples in FSPed samples.     

Revealing quantum correlation by negativity of the Wigner function

We analyze two two-mode continuous variable separable states with the same marginal states. We adopt the definition of classicality in the form of well-defined positive Wigner function describing the state and find that although the states possess positive local Wigner functions, they exhibit negative Wigner functions for the global states. Using the negativity of Wigner function as an indicator of nonclassicality, we show that despite these states possess different negativities of the Wigner function, they do not reveal this difference as phase space nonclassicalities such as negativity of the Mandel Q parameter or quadrature squeezing. We then concentrate on quantum correlation of these states and show that quantum discord and local quantum uncertainty, as two well-defined measures of quantum correlation, manifest the difference between negativity of the Wigner functions. The non-Gaussianity of these states is also examined and show that the difference in behavior of their non-Gaussianity is the same as the difference between negativity of their Wigner functions. We also investigate the influence of correlation rank criterion and find that when the states can be produced locally from classical states, the Wigner functions cannot reveal their quantum correlations.