Jn. Han et al., Analysis of anodic current transient and beam deflection transient simultaneously measured from Pd foil electrode pre-charged with hydrogen, J ELEC CHEM, 499(1), 2001, pp. 152-160
Anodic current and beam deflection transients were measured simultaneously
on a Pd foil electrode pre-charged with hydrogen at - 0.02 and 0.09 V(RHE)
in 0.1 M NaOH solution as a function of the hydrogen discharging potential.
From the analysis of the anodic current transient measured, it is recogniz
ed that when the preceding potential jump is small enough to be below the t
ransition discharging potential and this is followed by subjecting the elec
trode surface to a constant discharging potential, the hydrogen concentrati
on corresponding to the discharging potential is not fixed at the electrode
surface, but the change in surface concentration with time is then determi
ned by the Butler-Volmer equation. From the hydrogen concentration profile
transient simulated under the two constraints at the electrode surface depe
nding on the discharging potential, we calculated numerically the transient
of the deflection in the tensile direction caused by a smaller molar volum
e of alpha -PdHdelta near the surface region than that in the inner region
of the electrode during the hydrogen extraction. By comparison of the measu
red transient with that calculated, the movement of the maximum deflection
in tensile and compressive directions was discussed in terms of the positiv
e gradient of the molar volume towards the inner direction and the negative
gradient due to the formation of a PdOH phase on the electrode surface, re
spectively. (C) 2001 Elsevier Science B.V. All rights reserved.