Ke. Pomykal et Ns. Lewis, MEASUREMENT OF INTERFACIAL CHARGE-TRANSFER RATE CONSTANTS AT N-TYPE INP CH3OH JUNCTIONS/, JOURNAL OF PHYSICAL CHEMISTRY B, 101(14), 1997, pp. 2476-2484
Steady-state current density vs potential methods have been used to me
asure interfacial electron-transfer rate constants at n-type indium ph
osphide/liquid junctions. n-InP/CH3OH-1,1'-dimethylferrocene(+/0), n-I
nP/CH3OH- ferrocene(+/0), nP/CH3OH-tetrahydrofuran-decamethylferrocene
(+/0), and n-InP/CH3OH-1,1'-diphenyl-4,4'-dipyridinium(2+/+.) contacts
displayed bimolecular kinetic behavior in which the observed current
density was first order in the concentration of electrons at the semic
onductor surface and in the concentration of accepters in the solution
. Differential capacitance potential measurements were used to determi
ne the energetics for the charge-transfer process as well as to determ
ine the concentration of electrons at the semiconductor surface as a f
unction of applied potential. These measurements indicated that the vo
ltage dropped across the semiconductor space charge region varied line
arly with changes in the Nernst potential of the solution, as expected
for an ideally behaving semiconductor/liquid junction. The measured c
harge-transfer rate constants, k(et) for these systems were approximat
e to 10(-16) cm(4) s(-1), in excellent agreement with previous theoret
ical predictions.