39
Fig. 5.3 Cyclic
voltammetry profiles of
hydrogen adsorption and
the first anodic sweep into
the oxide formation for Pt
(11 1 1) and Pt(100)
surfaces in 0.1M KOH.
Reproduced from [6] with
permission
by probing the voltammetry profiles of the exposed Pt atoms upon the irreversible
adsorption of Bi and Tl, or Ge which preferentially adsorb on (111) and (100) faces,
respectively [14]. The deconvolution of the hydrogen region revealed that hydrogen
adsorption on (100) proceeds in 0.4–0.2 V region with a maximum around 0.28 V
whereas that on (111) also commences around 0.4 V but continues throughout entire
hydrogen adsorption region without distinct features on the voltammetry profile.
The prominent band around 0.12 V (c. f. Fig. 5.1) and the small peak between the
two most prominent ones (around 0.2 V) have been ascribed to H UPD on the sides
and vertices. It has been shown that the distribution of (100) and (111) faces on
uniform nanoparticle surfaces (e.g. cuboctahedron) depends on the particle size,
which in turn depends on the number of atoms in the sides [15]. Adzic’s group correlated the particle size with the average coordination numbers of the atoms in the
particle and was able to evaluate the particle size of the smallest monoatomic and
polyatomic nanoparticles (< 5 nm) by Extended X-ray absorption fine structure
(EXAFS, see Sect. 7.4.2), which is otherwise difficult to measure with other laboratory techniques (e.g. x-ray diffraction or x-ray microscopy) [16].
5.1 Hydrogen Adsorption on Platinum Metals
Fig. 5.3 Cyclic
voltammetry profiles of
hydrogen adsorption and
the first anodic sweep into
the oxide formation for Pt
(11 1 1) and Pt(100)
surfaces in 0.1M KOH.
Reproduced from [6] with
permission
by probing the voltammetry profiles of the exposed Pt atoms upon the irreversible
adsorption of Bi and Tl, or Ge which preferentially adsorb on (111) and (100) faces,
respectively [14]. The deconvolution of the hydrogen region revealed that hydrogen
adsorption on (100) proceeds in 0.4–0.2 V region with a maximum around 0.28 V
whereas that on (111) also commences around 0.4 V but continues throughout entire
hydrogen adsorption region without distinct features on the voltammetry profile.
The prominent band around 0.12 V (c. f. Fig. 5.1) and the small peak between the
two most prominent ones (around 0.2 V) have been ascribed to H UPD on the sides
and vertices. It has been shown that the distribution of (100) and (111) faces on
uniform nanoparticle surfaces (e.g. cuboctahedron) depends on the particle size,
which in turn depends on the number of atoms in the sides [15]. Adzic’s group correlated the particle size with the average coordination numbers of the atoms in the
particle and was able to evaluate the particle size of the smallest monoatomic and
polyatomic nanoparticles (< 5 nm) by Extended X-ray absorption fine structure
(EXAFS, see Sect. 7.4.2), which is otherwise difficult to measure with other laboratory techniques (e.g. x-ray diffraction or x-ray microscopy) [16].
5.1 Hydrogen Adsorption on Platinum Metals