University of California, Davis,
researchers have proposed a new way of thinking about the chemical reactions between
water and metal oxides. Their work appears in Nature Materials.
The new paradigm could lead to
a better understanding of corrosion and how toxic minerals leach from rocks and
soil. It could also help in the development of “green” technology, such as new types
of batteries or catalysts for splitting water to produce hydrogen fuel.
“This is a global change in
how people should view these processes,” said William Casey, UC Davis professor
of chemistry and co-author of the study with James Rustad, a former geology
professor at UC Davis who now works as a scientist at Corning Inc. in New York.
Previously, when studying the
interactions of water with clusters of metal oxides, researchers tried to pick
and study individual atoms to assess their reactivity. But “none of it really
made sense,” Rustad said.
Using computer simulations
developed by Rustad, and comparing the resulting animations with laboratory
experiments by Casey, the two found that the behavior of an atom on the surface
of the cluster can be affected by an atom some distance away.
Instead of moving through a sequence
of transitional forms, as had been assumed, metal oxides interacting with water
fall into a variety of “metastable states”—short-lived intermediates, the
researchers found.
For example, in one of Rustad’s animations, a water molecule approaches an
oxygen atom on the surface of a cluster. The oxygen suddenly pulls away from
another atom binding it into the middle of the cluster and leaps to the water
molecule. Then the structure collapses back into place, ejecting a spare oxygen
atom and incorporating the new one.
