Oxygen atoms behave differently while interacting with titanium crystals By: Gabriel Gache Usually,
when a metal catalyst reacts with an oxygen molecule, the individual
split oxygen atoms behave in identical ways. It seems that this is not
the case when oxygen molecule interacts with titanium metal. When the
two oxygen atoms get split up, one remains embedded into the titanium
crystalline structure, while the other is free to move a few positions
over to another location, after which it is also captured and planted
into the titanium metal.
Although titanium is not exceptional as
a metal catalyst,the new findings may lead to the creation of better
catalysts for the future fuel cell devices and solar fuel cell, which
are thought to power the next generation of vehicles. The study was
conducted at the Department of Energy's Pacific Northwest National
Laboratory and led by scientist Igor Lyubinetsky.
Oxygen has
great affinity towards most of the substances in the periodic table of
elements, thus towards metals in general. However, while interacting
with titanium, oxygen seems to experience preferential behavior; one of
the oxygen atoms extracts energy from the second in order to travel
more across the surface, while the other remains embedded in the
location where the oxygen molecule was split up. Generally, when such
reactions take place, each of the two atoms should get an equal amount
of energy.
For example, the oxygen reaction with platinum
separates the two oxygen atoms and propels them towards opposite
directions, and after traveling a fair distance across the surface of
the metal they will eventually stop to form bonds with it. In Chemistry
terminology, the atom that receives extra level of energy is called, a
'hot' atom./ALIGN]
While
experimenting with a titanium oxide crystal, with titanium and oxygen
atoms lined up so that they would form alternating strips on the
surface, the researchers successfully created imperfections in the
surface of the crystal, by heating it up so that part of the oxygen
strips would become vacant. However, while probing the material with a
scanning tunneling microscope, the team realized that oxygen molecules
only reacted partially with the crystal to fill the vacant positions,
meaning soon after the oxygen molecule got split instead of bonding
into consecutive vacant positions, one atom would receive more energy
and embed itself some positions away from the first one.
Out of
a sample of 110 molecules, more than three quarters of the atoms would
have jumped one or more positions away from the location of the first.
In normal temperature and pressure conditions, the oxygen atoms in the
crystal lattice are immobile. But, the team argues that the extra
energy received by the 'hot' atom could be received during the bonding
process of the first one, and equivalent to about three times more than
the energy required to extract an oxygen atom from the crystal, which
is spent on moving across the surface. http://my.opera.com/rezadotcom/blog/oxygen-has-the-hotties-for-titanium
