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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 6 1 4

ENERGY TRENDS

researchers can tune the absorber to re- flect light of almost any shade required. Some parts of the absorbing layer can be covered with a thicker transparent dielectric layer than others, allowing researchers to create a single absorber with a rainbow of hues. http://english. sitp.cas.cn. NANOFASTENERS ENABLE NEXT-GENERATION FUEL CELLS Professor Hee-Tak Kim at the Ko- rea Advanced Institute of Science and Technology (KAIST) and his team de- veloped a new fastening system that bonds hydrogen and oxygen mechan- ically rather than chemically, opening the way to development of fuel cell membranes that are less expensive, easier to manufacture, stronger, and more efficient. A pattern of tiny cylin- drical pillars was molded on the face of the hydrocarbon membrane. The pil- lars protrude into a softened skin of the electrode with heat. Next, the mechan- ical bond sets and strengthens as the material cools and absorbs water. The hydrocarbon membrane is cast using silicone molds. “This physically fastened bond is almost five times stronger and hard- er to separate than current bonds be- tween the same layers,” says Kim. The newmethod also appears to offer a way to bond many types of hydrocarbon membranes that, until now, have been rejected because they could not be fas- tened robustly. This would make these membranes practical for a number of applications beyond fuel cells such as rechargeable “redox flow” batteries. kaist.edu.

Newmaterial stores energy and can be recharged hundreds of times.

and color—useful for turning building facades and roofs into energy-captur- ing exteriors without sacrificing aes- thetics. Because they also use similar materials as existing solar absorbers, this new kind of absorber could lead to wider use of solar thermal technol- ogy and greater energy efficiency, says Shao-Wei Wang, Shanghai Institute of Technical Physics. At the heart of this technology are layered surfaces called solar se- lective absorbers. The absorbers are covered with multiple layers of trans- parent dielectric materials, which can reflect light of a particular color. By changing the thickness of these layers,

POWER PAPER

Researchers at Linköping Univer- sity, Sweden, developed a new mate- rial consisting of nanocellulose and a conductive polymer that has an out- standing ability to store energy. One sheet of power paper, 15 cm in diam- eter and a few tenths of a millimeter thick, can store as much as 1 Farad— similar to today’s supercapacitors. The material can be recharged in seconds, hundreds of times. The new material set a world re- cord in simultaneous conductivity for ions and electrons and opens the door to continued development toward even higher capacity. Unlike traditional batteries and condensers, power pa- per is produced from simple materials, is lightweight, requires no dangerous chemicals or heavy metals, and is wa- terproof. For more information: Xavier Crispin, +46 (0)11 36 34 85, xavcr@itn.liu. se, www.liu.se/?l=en. VIBRANT BUILDINGS TURN LIGHT INTO ENERGY Researchers in China developed a new solar-light-absorbing surface that can have almost any design, pattern,

Photo of solar selective absorber array on a glass substrate, taken in direct sunlight.