Nanoscale platinum could bring hydrogen fuel-cell advances

March 18, 2004
Researchers from Sandia National Laboratories and the University of New Mexico have developed a new way to mimic photosynthetic proteins to manipulate platinum at the nanoscale.

The redesigned platinum could be used in many applications, including catalysis, sensors, optoelectronics, and magnetic devices, according to John Shelnutt, a Sandia scientist.

The technique is similar to photosynthesis, but instead of manufacturing sugar, the new method changes a platinum ion to neutral metal atoms. The photosynthetic protein mimics this repeatedly, depositing metal as desired at the nanoscale level. The method involves putting porphyrins, the active part of photosynthetic proteins, with platinum salt in a solution of ascorbic acid at room temperature. Lighting the porphyrins excites them into becoming catalysts for platinum reduction and deposition. As this happens, metal grows onto surfaces as thin sheets or in the form of balls.

Because the porphyrin remains attached to the platinum nanostructure and active in the presence of light, it can also perform other functions besides growing itself. For example, when exposed to light, the platinum nanostructure extracts hydrogen from water. This reaction could lead to new ways of building hydrogen fuel cells for vehicles.

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