1.1 Overview
5
Fig. 1.1 a Atomic undercoordination enhanced catalytic reactivity of Au/TiO 2 for CO oxidation at room temperature and b CO oxidation activity of Au nanoparticles deposited on different
oxides. Reprinted with permission from [62, 63]. Copyright 2004 American Association for the
Advancement of Science and Elsevier
of porous structures or metal organic framed (MOFs) nanostructures that have many
important application to chemical science and industry [58–61].
Figure 1.1a shows that the every third row of Au atoms added to a TiO 2 surface
that has already been covered with a full-layer of Au atoms could improve the CO
oxidation efficiency at room temperature by some 50 folds of the otherwise fully
Au-covered surface [62]. Au particle size reduction raises its CO oxidation ability
(Fig. 1.1b) and the ability of Guanine binding to the particle [64].
Likewise, the activation energy for N 2 dissociation is 1.5 eV lower at terrace
edges than that at the flat Ru(0001) skin, yielding at 500 K a desorption rate that is at
least 9 orders of magnitude higher on the terrace edges [65]. Similar attributes hold
for NO decomposition on Ru(0001) skin, H 2 dissociation on Si(100) skin [66], and
low-temperature nitridation of nano-structurally-roughened Fe skins [67].
Skin roughening with nanoscaled features forms an effective means improving
the catalytic ability of a substance. The reactivity is three orders higher in magnitude for ammonia synthesis at the Re(1121) and the Re(1120) kink edges than at a
smooth Re(0001) skin [68]. An addition of a certain kind of adsorbate roughens the
skins of Ni(210), Ir(210) [69], Rh(553) and Re(1231) [70] to improve their catalytic
efficiencies.
Undercoordinated atoms serve as the most active sites in reaction. A few percent
of adatoms in a specimen could raise sufficiently the reactivity of the specimen in
catalytic applications. The edged or faceted atoms account for ~70% of the total
catalytic activity of the medium. The even-undercoordinated adatoms on Rh(111)
skin favor the process of methane dehydrogenation more than atoms at steps or at
the terrace edges [71, 72]. Adatoms deposited on oxides can activate the C–H bond
scission [73], acetylene ciclomerization [74], and CO oxidation [75]. The catalytic
efficiency of the undercoordinated atoms increases as their coordination numbers
5
Fig. 1.1 a Atomic undercoordination enhanced catalytic reactivity of Au/TiO 2 for CO oxidation at room temperature and b CO oxidation activity of Au nanoparticles deposited on different
oxides. Reprinted with permission from [62, 63]. Copyright 2004 American Association for the
Advancement of Science and Elsevier
of porous structures or metal organic framed (MOFs) nanostructures that have many
important application to chemical science and industry [58–61].
Figure 1.1a shows that the every third row of Au atoms added to a TiO 2 surface
that has already been covered with a full-layer of Au atoms could improve the CO
oxidation efficiency at room temperature by some 50 folds of the otherwise fully
Au-covered surface [62]. Au particle size reduction raises its CO oxidation ability
(Fig. 1.1b) and the ability of Guanine binding to the particle [64].
Likewise, the activation energy for N 2 dissociation is 1.5 eV lower at terrace
edges than that at the flat Ru(0001) skin, yielding at 500 K a desorption rate that is at
least 9 orders of magnitude higher on the terrace edges [65]. Similar attributes hold
for NO decomposition on Ru(0001) skin, H 2 dissociation on Si(100) skin [66], and
low-temperature nitridation of nano-structurally-roughened Fe skins [67].
Skin roughening with nanoscaled features forms an effective means improving
the catalytic ability of a substance. The reactivity is three orders higher in magnitude for ammonia synthesis at the Re(1121) and the Re(1120) kink edges than at a
smooth Re(0001) skin [68]. An addition of a certain kind of adsorbate roughens the
skins of Ni(210), Ir(210) [69], Rh(553) and Re(1231) [70] to improve their catalytic
efficiencies.
Undercoordinated atoms serve as the most active sites in reaction. A few percent
of adatoms in a specimen could raise sufficiently the reactivity of the specimen in
catalytic applications. The edged or faceted atoms account for ~70% of the total
catalytic activity of the medium. The even-undercoordinated adatoms on Rh(111)
skin favor the process of methane dehydrogenation more than atoms at steps or at
the terrace edges [71, 72]. Adatoms deposited on oxides can activate the C–H bond
scission [73], acetylene ciclomerization [74], and CO oxidation [75]. The catalytic
efficiency of the undercoordinated atoms increases as their coordination numbers