TY - JOUR
T1 - A pulse radiolysis study to probe reduced platinum colloids in aqueous solution using optical and conductivity techniques
AU - Rabani, J.
AU - Fessenden, Richard W.
AU - Sassoon, Richard E.
PY - 1988
Y1 - 1988
N2 - Measurements of conductance changes accompanying the pulse radiolysis of aqueous solutions containing 2-propanol, methylviologen (MV2+), 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+, MV2+, H+, H2, and Ptc. The faster process, which was over in about 6 ms, is attributed to the equilibrium involving MV+, MV2+, and H+ with Ptc while the slower process, which takes ∼100 ms or more, is suggested to involve H2 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 adsorbed per electron increases with time to a value of about 0.7. Optical experiments at near-neutral pH suggested the adsorption of MV2+ on the catalyst to be important.
AB - Measurements of conductance changes accompanying the pulse radiolysis of aqueous solutions containing 2-propanol, methylviologen (MV2+), 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+, MV2+, H+, H2, and Ptc. The faster process, which was over in about 6 ms, is attributed to the equilibrium involving MV+, MV2+, and H+ with Ptc while the slower process, which takes ∼100 ms or more, is suggested to involve H2 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 adsorbed per electron increases with time to a value of about 0.7. Optical experiments at near-neutral pH suggested the adsorption of MV2+ on the catalyst to be important.
UR - http://www.scopus.com/inward/record.url?scp=0001142248&partnerID=8YFLogxK
U2 - 10.1021/j100319a055
DO - 10.1021/j100319a055
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AN - SCOPUS:0001142248
SN - 0022-3654
VL - 92
SP - 2379
EP - 2385
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 8
ER -