A range of platinum deposits, equivalent thicknesses (δ) 0.2 -2.5 nm have been synthesised on carbon and reduced titania (TiO x ) supports using physical vapour deposition on (10 x 10) arrays of electrodes. For δ < 1.0 nm, discrete platinum centres are formed and the TiO x supported platinum show two distinct characteristics; (a) a strong positive shift in the potential for the oxidation of monolayers of CO with decreasing loading of Pt leading to an inability to oxidise the CO on the lowest loadings and (b) a strong negative shift in the potential for the reduction of oxygen. Both observations can be understood in terms of an increase in the irreversibility of the Pt/PtO couple at such surfaces. The same trends, although significantly weaker, are seen with the carbon supported platinum, δ < 1.0 nm, and it is suggested that the Pt/PtO couple on carbon shows intermediate kinetics between Pt on TiO x and bulk Pt. These results have significant implications for understanding the mechanism of oxygen reduction on supported Pt catalysts and hence for the search for alternative supports to platinum for ORR electrocatalysts.
High throughput screening methodologies are expanded to synchrotron based x-ray absorption techniques. An environmental chamber, based on ultra-high vacuum equipment, has been developed allowing in situ studies on arrays of samples while X-ray absorption fine structure spectroscopy, Raman spectroscopy, mass spectrometry and/or Xray diffraction can be applied simultaneously to characterize the system under process conditions in a time-resolved manner. The chamber accommodates a diverse range of samples from surface science to materials chemistry to heterogeneous catalysis. Data acquisition and data logging software is developed to handle large quantities of divers but related information. New data logging, processing and analysis procedures and programs are developed which will allow fast structure-function relationships characterization.
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