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Laser-activated membrane introduction mass spectrometry (LAMIMS), a high-throughput screening method, evaluates heterogeneous catalysts under realistic reactor conditions. It is a precise, versatile system requiring no moving parts. The catalyst array is supported on carbon paper overlaid upon a silicone rubber membrane configured in a variation of membrane introduction mass spectrometry as introduced by Cooks. The carbon paper serves as a heat-dissipating gas diffusion layer that permits laser heating of catalyst samples far above the decomposition temperature of the polymer membrane that separates the array from the mass spectrometer vacuum chamber. A computer-controlled C[O.sub.2] bar code writing laser is used for fine-tune heating of the catalyst spots above the base temperature of the LAMIMS reactor. The detailed design and performance of LAMIMS is demonstrated on arrays of 'real world' bulk water--gas shift catalysts using natural and isotopically labeled reactor feed streams. A bulk catalyst array spot can be evaluated for activity and selectivity in as little as 1.5 min. All array screening results were confirmed by industrial microreactor evaluations.

Combinatorial screening of electrochemical catalysts by current-voltage methods can be unwieldy for large sample sizes. By converting the ions generated in an electrochemical half-cell reaction to a fluorescence signal, the most active compositions in a large electrode array have been identified. A fluorescent acid-base indicator was used to image high concentrations of hydrogen ions, which were generated in the electrooxidation of methanol. A 645-member electrode array containing five elements (platinum, ruthenium, osmium, iridium, and rhodium), 80 binary, 280 ternary, and 280 quaternary combinations was screened to identify the most active regions of phase space. Subsequent 'zoom' screens pinpointed several very active compositions, some in ternary and quaternary regions that were bounded by rather inactive binaries. The best catalyst, platinum(44)/ruthenium(41)/osmium(10)/iridium(5) (numbers in parentheses are atomic percent), was significantly more active than platinum(50)/ruthenium(50) in a direct methanol fuel cell operating at 60 ° C, even though the latter catalyst had about twice the surface area of the former., Combinatorial synthesis and analysis have become commonly used tools in bioorganic chemistry (1-11). Although the combinatorial (or multiple sample) approach to the discovery of inorganic materials has existed for more [...]

Density functional theory (DFT) calculated spectra was used to correlate the operando infrared (IR) spectroscopy, polarization modulated IR spectroscopy (PM-IRRAS) of Pt-Nafion interfaces, and attenuated total reflectance IR spectroscopy of bulk Nafion to understand the Nafion functional group coadsorption responsible for the Stark tuning of [CO.sub.ads] on high surface area fuel cell electrodes. A model of the Nafion-Pt interface with appropriate dihedral and native bond angles which was consistent with experimental and calculated spectra indicated direct adsorption of the C[F.sub.3] and S[O.sub.3.sup.-] functional groups on Pt.

Electron spin resonance (ESR) is used for monitoring the local environment of 2,2,6,6-tetramethyl-4-piperidone N-oxide (Tempone) spin probe in water and methanol mixtures in solution and in [Li.sup.+] ion exchanged Nafion 117 membranes. The probe has displayed significant local ordering in the aqueous phase of Nafion membranes that is diminished with increasing methanol concentration.

The potential-dependent C[O.sub.2] exhaust from the cathode of an operating direct methanol fuel cell (DMFC) is monitored by online electrochemical mass spectrometry (ECMS) with air and with [H.sub.2] at the cathode. Electron spin resonance (ESR) measurements of the rotational diffusion rate of a nitroxide spin probe in Nafion have provided information concerning the effect of the [C.sub.MeOH] on the local state of the polymer.

The in situ X-ray absorption spectroscopy, ex situ X-ray fluorescence and X-ray powder diffraction have helped in the analysis of phase segregated nanostructured PtRu anode catalysts in an operating direct methanol fuel cell. The extended X-ray absorption fine structure analysis has showed that the Ru-O bond lengths are shorter than those reported for Ru-O of ruthenium oxides, indicating that the phases in which the Ru resides in the catalysts are not similar to oxides.

(super 195)Pt NMR spectroscopic and electrochemical measurements are carried out on commercial Pt-Ru alloy nanoparticle samples to investigate the effect of high temperature annealing in different vacuum/gas-phase environments. The results suggest that optimizing the amount of surface Ru by heat treatment at temperatures near 200 degree Celsius, in a hydrogen atmosphere, is utilized to produce Pt-Ru alloy nanoparticles with high methanol oxidation activity.