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 °C). Upon gradually increasing the temperature, using a N2 atmosphere containing ∼1000 ppm O2, from 80 °C to 600 °C the viscous matrix is transformed into a black solid, in which Zn(II) is dispersed. The sample treated at 600 °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 °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 °C interval are conducted in vacuo, the formation of the ZnO phase is not observed.