Pt3Co nanoparticles are used to promote the oxygen reduction kinetics and increase the efficiency of proton exchange membrane (PEM) fuel cells. For the first time, aberration-corrected scanning transmission electron microscopy (STEM), STEM image simulations, and DFT calculations are combined to provide insight into the origin of enhanced catalysis of Pt3Co nanoparticles. Acid-leached nanoparticles exhibit a solid-solution structure but heterogeneous composition, while heat-treated nanoparticles exhibit an ordered structure, except for the first three surface layers where Pt enrichment is observed.

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The results of a variety of electrochemical tests indicate palladium hydride (β-PdH) functions as a thermodynamic reference electrode in three aprotic solutions containing H 2(g) and solvents of dichloromethane, dimethylsulfoxide, and acetonitrile. For enhanced electrical conductivity all solutions contained 0.2 M of an ionic liquid, 1-methyl-3-butyl imidazolium tetrafluoroborate. As is required of all thermodynamic reference electrodes (i) the potential of β-PdH was stable, (ii) its small amplitude anodic and cathodic polarization were reversible, and (iii) it exhibited Nernstian behavior assuming that the hydrogen cation activity is controlled by the concentration of adsorbed hydrogen, which is set by the partial pressure of H 2(g) . © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0421603jes] All rights reserved.Manuscript submitted October 30, 2015; revised manuscript received December 8, 2015. Published December 17, 2015 Palladium hydride (PdH) has long been used as a redox system for measurement of pH, and as a titration electrode in nonaqueous solvents.1 The present investigation of PdH as a reference electrode in aprotic solutions arose from an interest in applying electrochemical techniques to assess the corrosivity of crude oil. Specifically, the current study was an offshoot of our efforts to use cyclic voltammetry of platinum in crude oil as a means for identifying the presence and concentrations of redox active corrosive species, such as naphthenic acids, which contribute significantly to the corrosion of steels in crude oil.At present, TAN (Total Acid Number) is employed to estimate the corrosiveness of a crude oil. TAN is the number of mg of potassium hydroxide required to neutralize the acids present in a 1 g sample of crude.2 However, it has been known for some time that there is considerable scatter in plots of low and intermediate values of TAN versus crudes' corrosiveness.3,4 For this reason, we have investigated the possibility of employing electrochemical techniques to characterize the corrosivity of an unknown crude.There are two major obstacles preventing the use of electrochemical techniques to assess the corrosivity of crudes. The first is the high electrical resistivity of crude oil. In a separate study we have addressed the resistivity issue by a combination of the use of ultramicroelectrodes (UME) and the addition of a supporting electrolyte, which does not itself affect the solution's corrosivity. 5 Many virgin crude oils have electrical resistivities on the order of 1 × 10 8 ohm•cm, which, although it is a high value, is nevertheless sufficiently low to permit electrochemical testing by employing UMEs without the need for a supporting electrolyte. However, the main concern over a crude's corrosivity relates to co...

Naphthenic acid, a significant cause of corrosion of carbon-steel in crude oil, has been investigated at elevated temperatures using vibrational spectroscopic methods (Raman and Fourier transform infrared (FT-IR)). Unlike earlier reports of studies at ambient temperatures, these elevated temperature experiments performed on a series of carboxylic acids having structures similar to naphthenic acid components in crude oil and on a commercial naphthenic acid mixture show a progressive increase with increasing temperature in the concentration of monomer over the multimers, which drives the formation of iron naphthenate. This observation forms a reasonable basis for proposing a mechanism of corrosion in crude oil at temperatures closer to the boiling point of naphthenic acids, which proceeds through the acid monomer.