Synthesis of ZnO-carbon composites and imprinted carbon by the pyrolysis of ZnCl2-catalyzed furfuryl alcohol polymers

Porous ZnO-carbon composites were produced from homogeneous mixtures of furfuryl alcohol-ZnCl2. ZnCl2, acting as a Lewis acid, promotes the polymerization of furfuryl alcohol at low temperatures (60-70 degrees C). Upon gradually increasing the temperature, using a N-2 atmosphere containing similar to 1000 ppm O-2, from 80 degrees C to 600 degrees C the viscous matrix is transformed into a black solid, in which Zn(II) is dispersed. The sample treated at 600 degrees C is covered by an uniform layer of ZnO microcrystals that are embedded in the carbonaceous matrix. The underlying carbon support contains a distribution of holes, whose size and shape is related to the shape of the ZnO microcrystals. Further heating in the 600-800 degrees C range leads to the disappearance of the ZnO phase, which after reduction to volatile Zn, leaves a pure carbon film that retains the original pores. The use of an inorganic Lewis acid as a precursor of a highly volatile metal, which acts as templating agent for the pores in the resulting carbon, is a novel result. If the thermal treatments in the 80-800 degrees C interval are conducted in vacuo, the formation of the ZnO phase is not observed. (C) 2007 Elsevier B.V. All rights reserved.