Chemische Reaktionen lassen Elektronen nicht kalt : über die verschlungenen Wege der Reaktionswärme an Metalloberflächen

Die Chemoelektronik spannt eine Brücke ziwschen den Welten der elektronischen Bauelemente und der Oberflächenchemie. Mit ihrer Hilfe lassen sich alte Fragen neu beantworten. Eine davon handelt von dem Rätsel, wie die freiwerdende Energie bei chemischen Reaktionen an Oberflächen auf den Festkörper übertragen wird.

Chemical reactions on surfaces play an important role in the fields of catalysis, chemistry, gas sensing and gas catalytic conversion. They release energy, which – in the long run – leads to heat. However, little is know about the mechanisms of energy transfer into the surface. Heretofore, the direct conversion of chemical energy into heat (phonons) has been considered the dominant path of energy transfer. Today, the use of new experimental methods including thin-film electronic devices, has revealed an alternative way of energy transfer: electrons in the surface are excited by the reaction, which then relax and heat up the surface. The authors of the article describe the design and application of two different devices, Schottkydiodes and metal-insulator-metal contacts, to detect the chemically induced hot electrons. Similar to solar cells, which produce electric currents when they are illuminated, the chemoelectric devices give currents when they are exposed to reactive gases. This effect may be used to study the kinetics of the reactions and to develop new kinds of gas sensors.

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