Kj. Stevenson et Hs. White, ELECTROCHEMISTRY OF ORGANIC REDOX LIQUIDS AT ELEVATED PRESSURES, Journal of physical chemistry, 100(48), 1996, pp. 18818-18822
The effect of hydrostatic pressure on the 1-e(-) reductions of acetoph
enone (AP) and nitrobenzene (NB) in the absence of an inert solvent is
reported. Steady-state voltammetric responses for these redox systems
are obtained at a 12.5 mu m radius Pt microdisk in a three-electrode,
high-pressure electrochemical cell. Reduction of 8.0 M AP and 9.1 M N
B in solutions containing only a small quantity of supporting electrol
yte (0.2 M [(n-butyl)(4)N]PF6) yields well-defined sigmoidal-shaped vo
ltammetric waves over the range of pressures investigated (P = 1-1000
bar). Transport-limited currents for both AP and NB reduction are show
n to decrease linearly with increasing pressure. Apparent (or integral
) diffusion coefficients (D-app) are computed from the voltammetric li
miting currents for AP and NB reduction and compared to bulk solution
molecular diffusivities (D) measured for a redox-active molecule (deca
methylferrocene) added to the solutions at low concentration (similar
to 16 mM). The relative decreases in D-app and D with increasing press
ure are essentially identical in both NB and AP solutions for pressure
s up to 1000 bar. The results indicate that transport-limited currents
for the reduction of these organic liquids are determined solely by d
iffusive processes.