Modified porous carbon materials as catalytic support for cathodic reduction of dioxygen Stanis»aw Biniak * , Mariusz Walczyk, Grzegorz S. Szyman ´ski Faculty of Chemistry, Nicolaus Copernicus University, ul.Gagarina 7, 87-100 Torun ´, Poland Received 18 February 2002; received in revised form 7 April 2002; accepted 15 April 2002 Abstract Activated carbon materials were modified by generating several functional groups containing oxygen and/or nitrogen atoms on their surfaces. Surface properties of obtained carbon samples were investigated. The point of zero charge was determined by different methods. The catalytic properties of these materials in the decomposition of hydrogen peroxide and in the electrochemical reduction of dioxygen in aqueous electrolytes have been studied. The catalytic activity for O 2 reduction correlates with that for HO 2  decomposition. A linear relationship was derived for the dioxygen reduction peak potential and the decomposition rate constant. Thus, the selection of active catalysts for the heterogeneous decomposition of HO 2  is a good starting point for the design of a carbon-based oxygen cathode. D 2002 Elsevier Science B.V. All rights reserved. Keywords: Oxygen electroreduction; Activated carbon; Functional groups 1. Introduction In recent decades, much effort has been directed toward the development of carbon- based electrode materials with high catalytic activity for the electrochemical reduction of oxygen because of the importance of this reaction in fuel cells and air batteries [1,2]. The direct, four-electron reduction of O 2 to H 2 O 2 is difficult to achieve at electrode potentials near the thermodynamically allowed values, and metal complexes supported on carbon are frequently employed as catalyst to enhance the rate of the electroreduction of O 2 . It was found that the efficiency of a catalyst is strongly affected by the functional groups 0378-3820/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII:S0378-3820(02)00182-0 * Corresponding author. Tel.: +48-56-611-4549; fax: +48-56-654-2477. E-mail address: sbiniak@chem.uni.torun.pl (S. Biniak). www.elsevier.com/locate/fuproc Fuel Processing Technology 79 (2002) 251– 257