It was a crisp, classic fall day in Cambridge, but little of the golden
afternoon sunlight trickled down to Cynthia Friend’s laboratory in the
basement of the Harvard chemistry building.
Yet sunlight and gold are key to an intriguing research project taking
shape here, combining the expertise of Friend, a professor of chemistry
and materials science, and Katharina Al-Shamery RI ’09, a German scientist who spent the fall semester of 2008–2009 in Friend’s lab on a Radcliffe Institute fellowship.
By exploiting new materials — such as semiliquid suspensions of gold
nanoparticles — the two scientists hope to improve the process of
“splitting water” with sunlight to produce hydrogen and oxygen. Thus
fluctuating and unpredictable — but renewable — solar energy would be
converted into storable hydrogen fuel, the basis of the proposed
“hydrogen economy” that could reduce dependence on fossil fuels and
combat global warning.
project has a very specific goal,” said Al-Shamery. “We want to use
solar energy to produce hydrogen as a means of storing energy, and to
do this we are working with very new materials that have emerged in the
past few years, which we believe will make the process more efficient.”
Al-Shamery, who was recognized as one of the outstanding female
researchers at the Max Planck Society in Berlin, has a broad, valuable
background for the current project: Her research interests include
surface chemistry, materials science, heterogeneous catalysis (an
important process in solar energy conversion), nanocrystal engineering,
Being able to work with Al-Shamery at Harvard “is great for me,” Friend
commented, “because she brings expertise I don’t have. This is a new
project I had in mind, and when I visited her last year in Germany, we
discussed the possibility of her coming to Harvard on a Radcliffe
Today, Al-Shamery was in her mentor role, letting the junior members of
the team— postdoc Anne Co and students Stephen Jensen and Bingjun Xu — do
the show-and-tell. They did their best to explain to a layperson the
photochemical experiments they were planning, while demonstrating the
instruments and equipment crucial to the task.
The main attraction was a tabletop steel vacuum chamber surrounded by a
thicket of metal tubes and wires and optical fibers that supply
artificial sunlight and electricity and pump gases in and out to create
photochemical reactions. The device is wrapped in crinkled aluminum
foil, giving it a slightly homebuilt look, and has a transparent
viewing port for observing what happens within.
“The [low] pressures we can get down to are even slightly better than
in space,” Jensen said with a touch of pride. “We will shine light at
the surface of materials inside the chamber and do reactions. … We
want to make sure that stray molecules from the atmosphere don’t
interfere with the experiments we want to do.”
Extracting hydrogen and oxygen from water “sounds simple,” Friend said,
“but water is very stable, and it is hard to make it go back the other
way” to release its components. “You need materials that absorb light
and make possible several different electron-transfer processes.” These
processes can take place on solid surfaces, similar to processes in a
car’s catalytic converter, she said.
Putting gold into the equation is a recent development, the scientists
explained. In the form of nanoparticles, gold is more active than
usual. Gold nanoparticles (about 10 billion would fit on the dot of a
printed “i”) may also have a role in new medical applications,
including cancer therapy.
For water-splitting, the gold particles function as miniature antennae
that transfer energy to nearby semiconductor materials, which then
separate electrons from their atomic locations to help drive reactions.
Titania, the material that makes paint, plastics, and many other
materials white, is an example of a semiconductor that Al-Shamery and
Friend will marry to the gold “antennae.”
Both Al-Shamery and Friend emphasize that there is a long road between
fundamental research like theirs and real-world applications. If
successful, this work will ratchet up the efficiency of water splitting
and could bring closer the goal of alternative energy sources. In
addition to extracting hydrogen from water as a method of fuel storage,
the process might be used to reduce carbon dioxide to carbon monoxide,
which could be converted to a nonpolluting substance. “This might
possibly help us with the greenhouse-gas emission problem,” Friend said.
Al-Shamery’s time at Radcliffe was up at the end of 2008, but the
collaboration “will have a much longer lifetime than that,” Friend
said. Currently, she hopes to incorporate the project in a much larger
grant proposal on alternative energy research that she has submitted to
the Department of Energy.
Al-Shamery, who is something of an exception as a woman reaching a high
level in science in Germany, spent some of her time at Radcliffe
collecting information on obstacles to gender parity in scientific
fields. She recently reviewed a Norwegian study that found, perhaps
counterintuitively, that women in less-developed countries are
participating in science and engineering at greater rates than they are
in industrialized Western nations. “It found that in countries like
Uganda, the Philippines, and Egypt, girls are extremely interested in
science and engineering, more so than in Western European countries and
Japan,” Al-Shamery said.
Showing a flair for public relations, Al-Shamery organized a
display of scientific womanpower to take place the night of
April 30, 2009, in the Mines of Rammelsberg, a mountain site in Germany
where silver was mined for a thousand years, which is now a museum. She
chose the date to coincide with the night of Beltane, a Celtic pagan
celebration of fertility and the beginning of summer, when, it is said,
witches fly to Rammelsberg mountain for an annual dance.
“The meeting is called ‘From the Witches’ Cauldrons of Materials
Science,’” Al-Shamery said. Nine woman scientists were scheduled to speak,
representing various career stages from postdoc all the way up to
director within the Max Planck Society.
“The idea,” she said, “is to set an example for other women that being a natural scientist is an exciting profession.”
Richard Saltus is a senior science writer/editor at the Dana-Farber Cancer Institute in Boston. This article was previously published in the Radcliffe Quarterly.