A physicist at
the University of York has played a key role in international research which
has made an important advance in establishing the catalytic properties of gold
at a nano level.

Keith McKenna was
part of a research team which discovered that the catalytic activity of
nanoporous gold (NPG) originates from high concentrations of surface defects
present within its complex 3D structure.

The research,
which is published online in Nature Materials,
has the potential to assist in the development of more efficient and durable
catalytic converters and fuel cells because nanoporous gold is a catalytic
agent for oxidizing carbon monoxide.

Bulk gold—the
sort used in watches and jewelry—is inert but nanoporous gold possesses high
catalytic activity towards oxidation reactions. The research team, which also
included scientists from Japan, China, and the U.S., discovered, that this
activity can be identified with surface defects found within its complex
nanoporous structure. While nanoporous gold exhibits comparable activity to
nanoparticulate gold, it is considerably more stable making it attractive for
the development of catalysts with high performance and long lifetimes.

They created NPG
by immersing an alloy of gold and silver in a chemical solution which removed
the latter metal to create a porous atomic structure. Then, using transmission
electron microscopy, they were able to detect evidence that the surface defects
on the NPG were active sites for catalysis and the residual silver made them
substantially more stable.

McKenna, of the
Department of Physics at the University of York, said: “Unlike gold
nanoparticles, dealloyed NPG is unsupported so we are able to monitor its
catalytic activity more accurately. We found that there are many surface
defects present within the complex structure of NPG which are responsible for
the high catalytic activity.

“This work has
given us a greater understanding of the catalytic mechanisms of NPG which will,
in turn, shed light on the mechanisms of gold catalysis more broadly.”

Source: University of York