100
3 Potential- or Adsorbate-Induced Changes in Surface Stress …
By the way, it seems difficult to explain convincingly the reason why the signreversal of ζ g,q from minus to plus takes place at the transition from oxygen adsorption
layer to surface oxide layer (PtO or PdO). Viswanath et al. [50] tried to explain the
sign-reversal of ζ g,q by regarding the surface oxide layer as a semiconductor with
weak electronic screening. If the electronic screening on the PtO surface is less
effective than on the clean Pt surface, the excess charge would be able to penetrate
deeper. In the case where the oxide-covered surface is more negatively charged (q
< 0), the electrons penetrated in the oxide layer may fill the antibonding valence band
states to weaken the Pt–O bonds, expanding the surface, i.e., g < 0, thereby leading
to the plus sign of ζ g,q . Conversely, in the case where the oxide-covered surface is
more positively charged (q > 0), the extraction of electrons from the oxide layer may
deplete the antibonding valence band states to strengthen the Pt-O bonds, contracting
the surface, i.e., g > 0, thereby leading to the plus sign of ζ g,q .
Apart from ζ g,q , let us discuss briefly the sign-reversal of
∂g
∂ E
ε
. The Gokhshtein
equation (see Eq. (1.119) in Sect. 1.8 of Chap. 1) indicates that the sign-reversal of
∂g
∂ E
ε
takes place when the inequality of −q <
∂q
∂ε
E
is reversed to −q >
∂q
∂ε
E
.
It is deduced that the sign-reversal of
∂g
∂ E
ε
observed by the piezoelectric detection
in the oxide formation/reduction region of the Pt [44, 45] and Pd [46, 47] electrodes
results from the significant change of
∂q
∂ε
E
accompanying the sign-reversal. The
change in electronic structure of the Pt or Pd electrode surface due to surface oxide
formation and reduction should be inevitably linked to the change of
∂q
∂ε
E
.
References
1. Kolb DM (1993) Surface reconstruction at metal-electrolyte interfaces. In: Lipkowski J, Ross
PN (eds) Structure of electrified interfaces. VCH Publishers Inc, New York, pp 65–102
2. Kolb DM (1996) Prog Surf Sci 51:109–173
3. Van Hove MA, Koestner RJ, Stair PC, Bibérian JP, Koesmodel KK, Bartos I, Somorjai GA
(1981) Surf Sci 103:189–238
4. Moritz W, Wolf D (1985) Surf Sci 163:L655–L665
5. Möller J, Niehus H, Heiland W (1986) Surf Sci 166:L111–L114
6. Bott M, Hohage M, Michely T, Comsa G (1993) Phys Rev Lett 70:1489–1492
7. Ibach H (2006) Physics of surfaces and interfaces. Springer-Verlag, Berlin
8. Ibach H, Bach CE, Giesen M, Grossmann A (1997) Surf Sci 375:107–119
9. Bach CE, Giesen M, Ibach H (1997) Phys Rev Lett 78:4225–4228
10. Kolb DM, Schneider J (1985) Surf Sci 162:764–775
11. Eberhardt D, Santos E, Schmickler W (1996) J Electroanal Chem 419:23–31
12. Ibach H, Santos E, Schmickler W (2003) Surf Sci 540:504–507
13. Needs RJ, Mansfield M (1989) J Phys: Condens Matter 1:7555–7563
14. Payne MC, Roberts N, Needs RJ, Needels M, Joannopoulos JD (1989) Surf Sci 211/212:1–20
15. Fiorentini V, Methfessel M (1993) Scheffler. Phys Rev Lett 71:1051–1054
16. Haftel MI, Rosen M (2001) Phys Rev B 64:195405-1-7
17. Gao X, Edens GJ, Hamelin A, Weaver MJ (1993) Surf Sci 296:333–35
18. Santos E, Schmickler W (2004) Chem Phys Lett 400:26–29
3 Potential- or Adsorbate-Induced Changes in Surface Stress …
By the way, it seems difficult to explain convincingly the reason why the signreversal of ζ g,q from minus to plus takes place at the transition from oxygen adsorption
layer to surface oxide layer (PtO or PdO). Viswanath et al. [50] tried to explain the
sign-reversal of ζ g,q by regarding the surface oxide layer as a semiconductor with
weak electronic screening. If the electronic screening on the PtO surface is less
effective than on the clean Pt surface, the excess charge would be able to penetrate
deeper. In the case where the oxide-covered surface is more negatively charged (q
< 0), the electrons penetrated in the oxide layer may fill the antibonding valence band
states to weaken the Pt–O bonds, expanding the surface, i.e., g < 0, thereby leading
to the plus sign of ζ g,q . Conversely, in the case where the oxide-covered surface is
more positively charged (q > 0), the extraction of electrons from the oxide layer may
deplete the antibonding valence band states to strengthen the Pt-O bonds, contracting
the surface, i.e., g > 0, thereby leading to the plus sign of ζ g,q .
Apart from ζ g,q , let us discuss briefly the sign-reversal of
∂g
∂ E
ε
. The Gokhshtein
equation (see Eq. (1.119) in Sect. 1.8 of Chap. 1) indicates that the sign-reversal of
∂g
∂ E
ε
takes place when the inequality of −q <
∂q
∂ε
E
is reversed to −q >
∂q
∂ε
E
.
It is deduced that the sign-reversal of
∂g
∂ E
ε
observed by the piezoelectric detection
in the oxide formation/reduction region of the Pt [44, 45] and Pd [46, 47] electrodes
results from the significant change of
∂q
∂ε
E
accompanying the sign-reversal. The
change in electronic structure of the Pt or Pd electrode surface due to surface oxide
formation and reduction should be inevitably linked to the change of
∂q
∂ε
E
.
References
1. Kolb DM (1993) Surface reconstruction at metal-electrolyte interfaces. In: Lipkowski J, Ross
PN (eds) Structure of electrified interfaces. VCH Publishers Inc, New York, pp 65–102
2. Kolb DM (1996) Prog Surf Sci 51:109–173
3. Van Hove MA, Koestner RJ, Stair PC, Bibérian JP, Koesmodel KK, Bartos I, Somorjai GA
(1981) Surf Sci 103:189–238
4. Moritz W, Wolf D (1985) Surf Sci 163:L655–L665
5. Möller J, Niehus H, Heiland W (1986) Surf Sci 166:L111–L114
6. Bott M, Hohage M, Michely T, Comsa G (1993) Phys Rev Lett 70:1489–1492
7. Ibach H (2006) Physics of surfaces and interfaces. Springer-Verlag, Berlin
8. Ibach H, Bach CE, Giesen M, Grossmann A (1997) Surf Sci 375:107–119
9. Bach CE, Giesen M, Ibach H (1997) Phys Rev Lett 78:4225–4228
10. Kolb DM, Schneider J (1985) Surf Sci 162:764–775
11. Eberhardt D, Santos E, Schmickler W (1996) J Electroanal Chem 419:23–31
12. Ibach H, Santos E, Schmickler W (2003) Surf Sci 540:504–507
13. Needs RJ, Mansfield M (1989) J Phys: Condens Matter 1:7555–7563
14. Payne MC, Roberts N, Needs RJ, Needels M, Joannopoulos JD (1989) Surf Sci 211/212:1–20
15. Fiorentini V, Methfessel M (1993) Scheffler. Phys Rev Lett 71:1051–1054
16. Haftel MI, Rosen M (2001) Phys Rev B 64:195405-1-7
17. Gao X, Edens GJ, Hamelin A, Weaver MJ (1993) Surf Sci 296:333–35
18. Santos E, Schmickler W (2004) Chem Phys Lett 400:26–29