3.4 Surface Stress Versus Surface Charge Density or Potential …
95
Fig. 3.15 Relationship between
lo or − and net surface charge obtained during cyclic
voltammetry in different potential regions between a −0.95 and 1.20 V (SHE), b −0.30 and 1.10 V
(SHE), and c 0.30 and 1.20 V (SHE) at a potential scan rate of 1 mV s −1 by in situ dilatometry for
the nano-porous Pt electrode in 0.7 M NaF solution [50]. HA: hydrogen adsorption, HD: hydrogen
desorption, OA: oxygen adsorption, OD: oxygen desorption, CC: electric double-layer charging,
and CD: electric double-layer discharging. Reprinted from [50], Copyright 2007, with permission
from Elsevier
The average values of ζ g,q = 1.51 V and ζ g,q = −0.75 V are obtained in the
hydrogen and oxygen regions, respectively. The cyclic voltammogram of the nanoporous Pt electrode in pH-neutral solution such as NaF solution exhibits the cathodic
shifts of the O-desorption and H-adsorption peaks as well as the anodic shifts of the
H-desorption and O-adsorption peaks as compared to the cyclic voltammogram of the
planar polycrystalline Pt electrode [50], since the transport kinetics in the pore of Pt
limits the electrode processes due to the potential gradient in the pore space. Despite
the large hysteresis for the cyclic voltammogram of the nano-porous Pt electrode,
the relationship between
l o
or − and in Fig. 3.15a separates sufficiently the
two processes of HA/HD and OA/OD. In Fig. 3.15b, although the potential region is
limited to the OA/OD process, the average value of ζ g,q = −0.71 V is nearly equal
to that for the OA/OD process in Fig. 3.15a.
In order to prepare the oxygenated surface, the cyclic voltammetry of the nanoporous Pt electrode was performed in 0.7 M NaF solution in the potential range of
95
Fig. 3.15 Relationship between
lo or − and net surface charge obtained during cyclic
voltammetry in different potential regions between a −0.95 and 1.20 V (SHE), b −0.30 and 1.10 V
(SHE), and c 0.30 and 1.20 V (SHE) at a potential scan rate of 1 mV s −1 by in situ dilatometry for
the nano-porous Pt electrode in 0.7 M NaF solution [50]. HA: hydrogen adsorption, HD: hydrogen
desorption, OA: oxygen adsorption, OD: oxygen desorption, CC: electric double-layer charging,
and CD: electric double-layer discharging. Reprinted from [50], Copyright 2007, with permission
from Elsevier
The average values of ζ g,q = 1.51 V and ζ g,q = −0.75 V are obtained in the
hydrogen and oxygen regions, respectively. The cyclic voltammogram of the nanoporous Pt electrode in pH-neutral solution such as NaF solution exhibits the cathodic
shifts of the O-desorption and H-adsorption peaks as well as the anodic shifts of the
H-desorption and O-adsorption peaks as compared to the cyclic voltammogram of the
planar polycrystalline Pt electrode [50], since the transport kinetics in the pore of Pt
limits the electrode processes due to the potential gradient in the pore space. Despite
the large hysteresis for the cyclic voltammogram of the nano-porous Pt electrode,
the relationship between
l o
or − and in Fig. 3.15a separates sufficiently the
two processes of HA/HD and OA/OD. In Fig. 3.15b, although the potential region is
limited to the OA/OD process, the average value of ζ g,q = −0.71 V is nearly equal
to that for the OA/OD process in Fig. 3.15a.
In order to prepare the oxygenated surface, the cyclic voltammetry of the nanoporous Pt electrode was performed in 0.7 M NaF solution in the potential range of