Methanol oxidation was studied on arc-melted Pt-Ru-Os alloys and on fuel cell catalysts prepared by the NaBH4 reduction of metal chloride salts. Both the arc-melted alloys and the high surface area catalysts have x-ray diffraction patterns indicative of single-phase face-centered cubic lattices. Hydrogen adsorption/desorption measurements on the polished alloy electrodes, in the presence of adsorbed CO (25°C), show that selected ternary alloys have significant hydrogen adsorption/desorption integrals at adsorption potentials where Pt:Ru (1:1) was fully blocked and higher integrals at all adsorption potentials studied up to 400 mV vs. the reference hydrogen electrode. In situ diffuse reflection Fourier transform infrared spectroscopy of the fuel cell anodes showed that the alloy catalysts had reduced CO coverage relative to Pt, with the ternary catalyst showing the least coverage. Steady-state voltammetry of the arc-melted alloys at 25°C confirmed that Pt-Ru-Os (65:25:10) is more active than Pt-Ru (1:1), particularly above 0.6 V. Pt-Ru-Os (65:25:10) methanol fuel cell performance curves were consistently superior to those of Pt-Ru (1:1) (e.g., typically at 90°C, 0.4 V; 340 mA/cm2 with Pt-Ru-Os vs. 260 mA/cm2 with Pt-Ru). InfrocluctionPractical direct methanol fuel cells require improved catalysts for the half-reaction CH3OH + H2O -* CO2 + 6W + 6e Although adsorptive dehydrogenation of methanol on ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.182.74 Downloaded on 2015-06-15 to IP

In-situ X-ray absorption near-edge structure (XANES) experiments were performed on a working reformateair fuel cell to study the structure of carbon supported Pt-Ru anode electro-catalyst. The fuel cell was operated in a normal mode without the use of supplemental electrolytes. A fresh membrane electrode assembly (MEA) and a conditioned MEA were studied at different operating conditions of the fuel cell and different feed (pure H 2 or H 2 /CO [100 ppm CO]) at the anode. The in-situ Pt L III -edge and Ru K-edge XANES of the fuel cell MEAs showed metallic characteristics under all operating conditions. These results demonstrate that, under the reducing conditions of normal fuel cell operation, the Pt-Ru catalyst exists as a metallic phase(s).

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Using a model cathode-electrolyte system composed of epitaxial thin-films of La1-xSrxMnO3-δ (LSM) on single crystal yttria-stabilized zirconia (YSZ), we investigated changes in the cation concentration profile in the LSM during heating and under applied potential using grazing incidence x-rays. Pulsed laser deposition (PLD) was used to grow epitaxial LSM(011) on YSZ(111). At room temperature, we find that Sr segregates to form Sr enriched nanoparticles and upon heating the sample to 700°C, Sr is slowly reincorporated into the film. We also find different amounts of Sr segregation as the X-ray beam is moved across the sample. The variation in the amount of Sr segregation is greater on the sample that has been subject to 72 hours of applied potential, suggesting that the electrochemistry plays a role in the Sr segregation.

A detailed extended x-ray absorption fine structure ͑EXAFS͒ study of CuInSe 2 and CuIn 3 Se 5 on Cu-K, InK , and Se-K edges was performed. It was found that CuInSe 2 and CuIn 3 Se 5 have well-defined local structure with the same average Cu-Se and In-Se bond lengths. They can be best described by structures containing weighted local tetrahedral cationic clusters around each Se: 2Cuϩ2In (kϭ8), and equal number of V Cu ϩCuϩ2In (k ϭ7) and V Cu ϩ3In (kϭ9), where k denotes the nominal number of valence electrons of the cation clusters. CuInSe 2 consists of 100% kϭ8 clusters and CuIn 3 Se 5 consists of 20% kϭ8 and 40% kϭ7 and 40% kϭ9 clusters. First-principles band structure calculations of various CuInSe 2 , CuIn 3 Se 5 and CuIn 5 Se 8 compounds confirmed that the average Cu-Se and In-Se bond lengths in various ordered vacancy structures are identical to within the calculation uncertainty, in agreement with the present EXAFS measurements. The first-principles calculations also find that the formation energy of several possible crystal structures for CuIn 3 Se 5 and CuIn 5 Se 8 are very similar, which explains why the long-range order of CuIn 3 Se 5 is not uniquely determined.