Available online at www.sciencedirect.com Journal of Photochemistry and Photobiology A: Chemistry 196 (2008) 143–153 Synthesis of ZnO–carbon composites and imprinted carbon by the pyrolysis of ZnCl 2 -catalyzed furfuryl alcohol polymers Federico Cesano, Domenica Scarano ∗ , Serena Bertarione, Francesca Bonino, Alessandro Damin, Silvia Bordiga, Carmelo Prestipino 1 , Carlo Lamberti, Adriano Zecchina Nanostructured Interfaces and Surfaces (NIS), Centre of Excellence, Department of Chemistry IFM, University of Turin, Centre of Reference INSTM, Via P. Giuria 7, I-10125 Torino, Italy Available online 6 August 2007 Abstract Porous ZnO–carbon composites were produced from homogeneous mixtures of furfuryl alcohol–ZnCl 2 . ZnCl 2 , acting as a Lewis acid, promotes the polymerization of furfuryl alcohol at low temperatures (60–70 ◦ C). Upon gradually increasing the temperature, using a N 2 atmosphere containing ∼1000 ppm O 2 , 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. © 2007 Elsevier B.V. All rights reserved. Keywords: ZnO–carbon composites; Microporous carbon; Morphology; Structure; Optical properties 1. Introduction Microporous carbons (MCs) have attracted a great attention in recent years due to the wide applicability to many fields, including catalytic supports, gas storage, molecular sieves, porous membranes and electrodes. Porous carbons are usually prepared by pyrolysis of suitable polymers in vacuum or in controlled atmosphere under inert gas flow. Polyacrylonitrile (PAN), phenolic resin, polyimides, poly(p-phenylene vinylene), polyvinyl acetate and polyfurfuryl alcohol (PFA) are the most commonly used precursors [1–8]. When compared to other pre- cursors, PFA (obtained by acid-catalyzed polymerization of the ∗ Corresponding author. Tel.: +39 011 6707834; fax: +39 011 6707855. E-mail addresses: federico.cesano@unito.it (F. Cesano), domenica.scarano@unito.it (D. Scarano), serena.bertarione@unito.it (S. Bertarione), francesca.bonino@unito.it (F. Bonino), alessandro.damin@unito.it (A. Damin), carmelo.prestipino@esrf.fr (C. Prestipino), carlo.lamberti@unito.it (C. Lamberti), adriano.zecchina@unito.it (A. Zecchina). 1 Current address: ESRF, BP 220, F-38043 Grenoble, France. monomer) provides a relatively high carbon yield. The formed carbon phase shows distinct microporosity and is character- ized by the presence of defects such as pentagons, heptagons, vacancies, impurities and other non-hexagonal rings [7,9,10]. PFA-derived carbons show bottle-like nano- and micropores, with narrow opening connected to larger voids. Their size dis- tribution is dramatically affected by pyrolysis conditions. The presence of pores of different sizes and shapes is evidenced by X-ray scattering (pores with 25–35 ˚ A pore diameters) and by selective adsorption of molecular probes with increasing size (pores with 3.8–4.8 ˚ A range) [1]. The catalysts promoting the polymerization of furfuryl alco- hol (FA) commonly reported in literature are (i) mineral acids (H 2 SO 4 , etc.) [8,11–13], (ii) organic acid (p-toluenesulphonic, etc.) [8,14,15], (iii) acid zeolites (HY, HZSM5) [16,17] and (iv) (I 2 , SnCl 4 , TiCl 4 ) [18–20]. In this study we have investigated the catalytic effect of a Lewis acid (ZnCl 2 ) on the polymerization of FA and the fate of the catalysts dispersed in the polymeric matrix upon thermal treatments in the 80–800 ◦ C interval under N 2 controlled atmosphere. To this purpose PFA resins have been first obtained by dissolving known quantities of ZnCl 2 (Lewis 1010-6030/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jphotochem.2007.07.033