In situ structural characterization of a platinum electrocatalyst by dispersive x-ray absorption spectroscopy

Using in-situ dispersive EXAFS spectroscopy, we have monitored the numbers of PtO and PtPt bonds and the charge on the Pt in parallel with cyclic voltammetry on Pt clusters in a polymer electrolyte fuel cell. Due to the increased sensitivity of this method, we detect small structural changes not previously reported for these clusters and can correlate these changes with specific reactions, ie H desorption or O adsorption in the double-layer region.

[1]  D. Sayers,et al.  Quantitative technique for the determination of the number of unoccupied d-electron states in a platinum catalyst using the L2,3 x-ray absorption edge spectra , 1984 .

[2]  H. Angerstein-Kozlowska,et al.  The real condition of electrochemically oxidized platinum surfaces , 1973 .

[3]  S. Conradson,et al.  A four‐point crystal bender for dispersive X‐ray absorption spectroscopy , 1993 .

[4]  P. Ross.  Characterization of alloy electrocatalysts for direct oxidation of methanol: new methods , 1991 .

[5]  Kingo Itaya,et al.  In situ scanning tunneling microscopy of platinum (111) surface with the observation of monatomic steps , 1990 .

[6]  F. Walsh,et al.  In situ studies of a dispersed platinum on carbon electrode using X-ray absorption spectroscopy , 1992 .

[7]  M. Peuckert,et al.  Oxygen Reduction on Small Supported Platinum Particles , 1986 .

[8]  B. Wu,et al.  Electrochemical study of the initial surface condition of platinum surfaces with (100) and (111) orientations , 1982 .

[9]  J. Rehr,et al.  Ab initio curved-wave x-ray-absorption fine structure. , 1991, Physical review. B, Condensed matter.

[10]  John A. Horsley.  Relationship between the area of L2,3 x‐ray absorption edge resonances and the d orbital occupancy in compounds of platinum and iridium , 1982 .

[11]  W. O'grady,et al.  In-situ time-resolved EXAFS study of the structural modifications occurring in nickel oxide electrodes between their fully oxidized and reduced states , 1991 .