SAGE-Hindawi Access to Research International Journal of Electrochemistry Volume 2011, Article ID 434186, 7 pages doi:10.4061/2011/434186 Research Article A Graphite Oxide Paper Polymer Electrolyte for Direct Methanol Fuel Cells Ravi Kumar, Mohamed Mamlouk, and Keith Scott School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne NE1 7RU, UK Correspondence should be addressed to Keith Scott, k.scott@ncl.ac.uk Received 14 June 2011; Revised 12 August 2011; Accepted 12 August 2011 Academic Editor: Jiujun Zhang Copyright © 2011 Ravi Kumar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A flow directed assembly of graphite oxide solution was used in the formation of free-standing graphene oxide paper of approx- imate thickness of 100 μm. The GO papers were characterised by XRD and SEM. Electrochemical characterization of the GO paper membrane electrode assembly revealed proton conductivities of 4.1 × 10 −2 S cm −1 to 8.2 × 10 −2 S cm −1 at temperatures of 25–90 ◦ C. A direct methanol fuel cell, at 60 ◦ C, gave a peak power density of 8 mW cm −2 at a current density of 35 mA cm −2 . 1. Introduction Polymer electrolyte fuel cells (PEMFCs) have been projected as promising power sources for many potential applications [1]. The present PEMFCs research is based on polymer electrolyte membranes which provide appropriate fuel cell performance in terms of conductivity, chemical, mechanical stability, durability, and fuel crossover [2, 3]. Perfluorinated sulphonic acids (PFSA-)- based membranes are widely used as these membranes show good conductivities in the range of 0.01 to 0.1 S cm −1 in a humid environment. However unsat- isfactory durability and reliability of these membranes hin- ders the successful commercialization of fuel cells. To im- prove the performance of polymer electrolyte fuel cells and replace the cell components like membranes, different ap- proaches have been employed: (1) development of Nafion- based composite membranes to increase the conductivity, mechanical strength, and chemical stability [4]: (2) direct use of functionalized materials like fullerene for polymer electrolyte fuel cells and PVDF mixed fullerene for direct me- thanol fuel cells [5, 6]. The preparation and characterization of graphene oxide paper was reported by Ruoff et al. [7], and they believed that these materials can be adopted for applications including molecular storage, ion conductors and super capacitors. The mechanism of proton conductivity in solids, is based on two methods; one is the vehicular model, where formation of an ion adduct with carrier molecule occurs—if it is water then protons form hydronium ions. In a non-vehicular model hopping of protons occurs from site to site without carrier molecules. The activation energy of proton conduc- tion depends on the distance between the hopping sites; if the distance is short, for example 0.24–0.25 nm, in case of two oxygen atoms, then proton conduction is free from kinetic activation [8, 9]. Hydration of GO incorporates the water molecule be- tween GO sheets which presumably form hydrogen bonds [7]. Scanning tunnelling microscopy shows oxygen atoms on GO are arranged in a rectangular pattern with a lattice con- stant of 0.27 nm × 0.41 nm [10]. Based on this information, GO presumably shows both types of conduction mechanism; with hopping of protons via oxygen atoms present on basal planes and edges, and with a vehicular mechanism, where, due to the presence water molecule between layers, protons might form hydronium ions. On the contrary, carbon based materials like fullerenol C 60 (OH) n have reported conductivi- ties of 7 × 10 −6 S cm −1 with no significant proton conduc- tivity for fuel cell application. Therefore GO is potentially interesting for use as polymer electrolytes in PEMFCs [11]. In the present paper, we report the characterization and use of