August 2007

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Scientists at the Argonne National Laboratory together with others at Northwestern and Michigan State universities have identified a new technique for cleaning contaminated water and potentially purify hydrogen via a new type of porous material. The team, headed by Argonne materials scientists Peter Chupas and Mercouri Kanatzidis, have created characterized porous semiconducting aerogels that in tests removed more than 99.99 % of the heavy metal mercury from contaminated water, reported a late-July release from Argonne. These aerogels which are made from chalcogenides - molecules made of up of a chalcogen such as sulfide, selenide or telluride, plus at least one electro-positive element - are expected to separate out impurities from hydrogen gas as they did mercury from that water by acting as a kind of sieve or selectively permeable membrane, the Argonne report said. The structure of these gels will allow them to tune their pore sizes or composition in order to separate particulate poisons from the hydrogen gas stream: gels made with so-called open platinum sites would extract carbon monoxide, a common poison for fuel cell catalysts, Chupas said. Aerogels offer a big advantage over powders, for example, because of their enormous surface area: One cubic centimeter of the aerogel could have a surface area as large as a football field, Kanatzidis said, and the bigger the surface area the better it can bind other molecules. A paper describing the work, “Porous semiconducting gels and aerogels from chalcogenide clusters,” appeared in the July 27 issue of “Science.”

Contact: Argonne media office, Sylvia Carson, 630/252-5510, scarson@anl.gov.