Application of pyrolysed iron(II) phthalocyanine and CoTMPP based oxygen reduction catalysts as cathode materials in microbial fuel cells Feng Zhao a,1 , Falk Harnisch a , Uwe Schro ¨der a, * , Fritz Scholz a , Peter Bogdanoff b , Iris Herrmann b a Institut fu ¨ r Chemie und Biochemie, Universita ¨ t Greifswald, Soldmannstrasse 16, 17489 Greifswald, Germany b Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, 14109 Berlin, Germany Received 26 September 2005; received in revised form 30 September 2005; accepted 30 September 2005 Available online 3 November 2005 Abstract The performance of iron(II) phthalocyanine (FePc) and cobalt tetramethoxyphenylporphyrin (CoTMPP) based oxygen reduction cat- alysts was studied in view of the application as cathode materials in microbial fuel cells. Galvanostatic and potentiostatic experiments were performed in order to compare the proposed materials to platinum and hexacyanoferrate(III) based systems. Additionally, two- chamber microbial fuel cell experiments were carried out to demonstrate that the transition metal based materials are well suitable to fully substitute the traditional cathode materials in microbial fuel cells. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Microbial fuel cells; Cathode; Oxygen; CoTMPP; Iron phthalocyanine; Pyrolysis 1. Introduction The recent interest in microbial fuel cells (MFCs) can be attributed to the endeavour of gaining access to the direct generation of electricity from biomass and waste [1–3]. Very different approaches have been developed to facilitate the electron transfer between microorganisms and the MFC anodes [4–6]. Thus, biofilm based MFCs have recently received much attention as they allow the highly beneficial combination of COD removal and electricity generation from waste water [2,5,7,8]. An approach that we are follow- ing in our lab are hydrogen mediated microbial fuel cells based on heterotrophic, photo-heterotrophic as well as purely photosynthetic microbiological activity [9–14]. Most efforts in the past have almost exclusively been devoted to the development of the MFC anode, whereas the cathode has been rather neglected. Only recently, increasing efforts have been made in developing new con- cepts for microbial fuel cell cathodes [15]. As the cathode materials usually platinum based oxygen electrodes [15,16] or, more often, ferricyanide served as an experi- mental electron acceptor (e.g. [17]). The latter material suffers from its inability to be regenerated (re-oxidised) by oxygen or air, which consequently requires a periodi- cal replacement of the exhausted catholyte solution. Plat- inum, however, as an excellent oxygen reduction catalyst, should be ruled out for microbial fuel cell application due to its high price. The development of oxygen reduction catalysts for fuel cell application represents a major research field, and a wealth of information is available on the mechanisms of the electrochemical oxygen reduction (see, as one example [18]) and potential oxygen reduction catalysts (e.g. [19,20]). Increasing efforts have been made to develop inexpensive 1388-2481/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.elecom.2005.09.032 * Corresponding author. Tel.: +49 3834 864330; fax: +49 3834 864451. E-mail address: uweschr@uni-greifswald.de (U. Schro ¨ der). 1 On leave from: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Remin Street, Changchun, Jilin 130022, PR China. www.elsevier.com/locate/elecom Electrochemistry Communications 7 (2005) 1405–1410