Pulse radiolysis study to probe reduced platinum colloids in aqueous solution using optical and conductivity techniques
Measurements of conductance changes accompanying the pulse radiolysis of aqueous solutions containing 2-propanol, methylviologen (MV/sup 2 +/), and colloidal Pt (Ptc) have been carried out in parallel with optical absorption measurements on the same systems in order to investigate the reactions involved in the loading of Ptc with reducing equivalents. Two stages could be distinguished in the equilibration of MV/sup +/, MV/sup 2 +/, H/sup +/, H/sub 2/, and Ptc. The faster process, which was over in about 6 ms, is attributed to the equilibrium involving MV/sup +/, MV/sup 2 +/, and H/sup +/ with Ptc while the slower process which takes approx. 100 ms or more, is suggested to involve H/sub 2/ produced by radiolysis. At pH values in the range 9-11, the conductivity signal was found to decay more slowly and to a smaller extent than the optical absorption. Thus the injection of charge into the catalyst particle is faster than the protonation of the charged catalyst. The number of protons absorbed per electron increases with time to a value of about 0.7. Optical experiments at near-neutral pH suggested the adsorption of MV/sup 2 +/ on the catalyst to be important.
- Research Organization:
- Hebrew Univ., Jerusalem (Israel)
- OSTI ID:
- 7004208
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 92:8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BIPYRIDINES
ABSORPTIVITY
ELECTRIC CONDUCTIVITY
RADIOLYSIS
PLATINUM
PROPANOLS
AQUEOUS SOLUTIONS
COLLOIDS
EXPERIMENTAL DATA
PULSE TECHNIQUES
ALCOHOLS
AZINES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
DISPERSIONS
ELECTRICAL PROPERTIES
ELEMENTS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
METALS
MIXTURES
NUMERICAL DATA
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM METALS
PYRIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
SOLUTIONS
TRANSITION ELEMENTS
400600* - Radiation Chemistry
400500 - Photochemistry