Journal of Power Sources 195 (2010) 475–479 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Short communication Enhancement of glucose electro-oxidation by an external electromagnetic field in direct-mode fuel cells J.-P. Spets a,∗ , M.A. Kuosa a , Y. Kiros b , T. Anttila c , J. Rantanen c , M.J. Lampinen a , K. Saari a a Helsinki University of Technology, Department of Energy Technology, Applied Thermodynamics, PO Box 4400, FI-02150 Espoo, TKK, Finland b Royal Institute of Technology-KTH, Department of Chemical Engineering and Technology, S100-44 Stockholm, Sweden c Oy Hydrocell Ltd., Minkkikatu 1-3, FI-04430 Järvenpää, Finland article info Article history: Received 9 February 2009 Received in revised form 5 May 2009 Accepted 26 June 2009 Available online 29 July 2009 Keywords: Direct-mode fuel cell Catalyst materials Glucose Electrochemical reforming abstract In this study a direct-mode fuel cell in which the fuel and electrolyte are mixed with each other is tested. An alkaline electrolyte is used. The direct-mode fuel cell is exposed to an externally generated electromagnetic field between electrodes to cause both the splitting of the fuel molecule into smaller units (i.e. electrochemical reforming) and an increase in the activity of catalyst materials on the fuel before electrochemical oxidation. The target is to create a fuel cell with a capacity range of a few mW cm -2 with glucose as a fuel. In the selected fuel cell type with glucose as the fuel, a maximum current density of 13 mA cm -2 was obtained. On the basis of the tests it seems to be possible to use the glucose-fuelled cell in small-scale applications, e.g. in small electronic devices. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The ideal fuel for fuel cells in power generation systems is the direct use of a fuel like glucose, which is produced from cellulose by hydrolysis, in the form of a liquid phase [1–4]. This allows easier use with negligible energy input for the enrichment of the fuel. Fuels such as glucose or other carbohydrates can easily be utilised by mixing them directly in the electrolyte without the use of any auxiliary reforming equipment, membrane barriers, or additional microbial cultures. Many earlier studies have been conducted on low-temperature direct or direct-mode fuel cells, in which metallic catalysts or enzymes were used in electrolytes with different pH values [1–17]. As far as glucose is concerned, the oxidation reactions are believed to take place to only a limited degree with very low Coulombic efficiency (CE) values of theoretical maximum value, and the total yield of electrons from the molecule is only two electrons from 24 available electrons [4,9,11,12,15]. In direct-mode fuel cells (DMFCs) in which a fuel and an aque- ous electrolyte are mixed with each other, the current densities have been very low. The current densities have ranged from 5 to 8 mA cm -2 [2,3], in comparison to current densities of several hun- dred mA cm -2 in direct fuel cells, which are supplied with either hydrogen or alcohols [18,19]. However, the use of direct-mode fuel ∗ Corresponding author. E-mail address: jukka-pekka.spets@tkk.fi (J.-P. Spets). cells is simple as they are equipped only with a metallic catalyst, avoiding the use of anion- or cation-selective membranes. Concern- ing the application of the direct-mode fuel cell, the membranes are regarded as being expensive and inducing resistance, and their effective operating times are limited. In the studies regarding direct bioorganic oxidations, the anodic catalyst materials have been com- posed of different Pt alloys or combinations with different materials [1–16]. 2. Bioorganic materials as a fuel source In this study, a DMFC with a function generator (FG) connection is used. The idea is to use the FG to produce an electromagnetic field between the electrodes. As a result of this the glucose molecule could start to vibrate and then split into smaller units in the elec- tromagnetic field (i.e. electrochemical reforming). The operating capacities of the anode and cathode catalysts could also increase as a result of the increased activity towards the fuel molecules. Ear- lier, the FG was used in fuel cells for the determination of internal resistances [20,21]. The use of a monosaccharide glucose (C 6 H 12 O 6 ) fuel is of great importance, because it can be produced easily by cat- alytic hydrolysis at elevated temperatures between 150 and 250 ◦ C from both starch and cellulose (polysaccharides) [22]. The target in this work is to produce a direct-mode bioorganic fuel cell with an alkaline electrolyte and with a power density production of a few mW cm -2 through the use of an effective and simple cell arrange- ment. In the development of the selected fuel cell, it is important both to increase the oxidation reactions in the liquid phase and 0378-7753/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2009.06.110