A Collaboration with a Long Lifetime: Radcliffe Fellow Katharina Al-Shamery and Harvard Chemistry Professor Cynthia Friend

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.

“Our 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, and femtochemistry.

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 fellowship.”

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 is organizing a display of scientific womanpower that will 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 will 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.

Photo: Al-Shamery (left) and Friend in safety glasses with the tabletop steel vacuum chamber in Friend’s lab. By Tony Rinaldo