12-02 :: February/March 2012

nanotimes News in Brief

Researcher at University of Auckland, New Zea- land, present a self-commutated artificial muscle motor that uses dielectric elastomer switches in the place of bulky external electronics. The motor simply requires a DC input voltage to rotate a shaft (0.73 Nm/kg, 0.24Hz) and is a step away from hard metallic electromagnetic motors towards a soft, light, and printable future. © APL

Benjamin M. O’Brien, Thomas G. McKay, Todd A. Gisby, and Iain A. Anderson: Rotating turkeys and self-commu- tating artificial muscle motors, In: Applied Physics Letters, Vol. 100(2012), February 13, 2012, Issue 7, Article 074108 [3 pages], DOI:10.1063/1.3685708: http://dx.doi.org/10.1063/1.3685708

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cantly less economical, since it requires much gre- ater quantities of palladium, which costs more than $650 an ounce. It is less environmentally friendly as well, because of the energy that must be used to extract the additional necessary palladium from raw ore. The new catalyst also behaves differently, says Georgios Kyriakou, a research assistant professor in chemistry and first author of the report. He helped determine that the single atom alloy was more effective in catalyzing hydrogenation than denser mixtures of palladium and copper.

Scientists at Tufts (US) have found a way to create a selective hydrogenation catalyst by scattering single atoms of palladium onto a copper base. This catalyst requires less of the expensive metal, and the process is greener, too, offering potentially significant economic and environmental benefits. Led by Charles Sykes, an associate professor of chemistry in the School of Arts and Sciences, the group of researchers heated up very small amounts of palladium to almost 1,000° Celsius (1,830° F). At that temperature, the metal evaporated like a gas, so that single atoms were released. These atoms, less than half a nanometer wide, embedded themselves into a copper metal surface about three inches away. Using a STM the researchers verified that single palladium atoms had indeed embedded themselves at scattered intervals in the copper. In a conventional metal catalyst, by contrast, palladium is used in clumps 5 to 10nm wide. This is signifi-

Individual atoms of palladium, represented by the yellow peaks, in the surface of copper help break hydrogen mo- lecules into two atoms. © Courtesy of Sykes Lab

Georgios Kyriakou, Matthew B. Boucher, April D. Jewell, Emily A. Lewis, Timothy J. Lawton, Ashleigh E. Baber, Heather L. Tierney, Maria Flytzani-Stephanopoulos, E. Charles H. Sykes: Isolated Metal Atom Geometries as a Strategy for Selective Heterogeneous Hydrogenations, In: Science, Vol. 335(2012), No. 6073, March 09, 2012, Pages 1209-1212, DOI:10.1126/science.1215864: http://dx.doi.org/10.1126/science.1215864 http://www.tufts.edu