Short communication Electrooxidation of ascorbic acid on polyaniline and its implications to fuel cells S.K. Mondal a , R.K. Raman b , A.K. Shukla b , N. Munichandraiah a,∗ a DepartmentofInorganicandPhysicalChemistry,IndianInstituteofScience,Bangalore560012,India b Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India Abstract l-Ascorbic acid (AA) has been shown to undergo oxidation on polyaniline (PANI) without a platinum-group catalyst. A direct ascorbic acid fuel cell (DAAFC) has been assembled by employing an anode coated with PANI catalyst. From the experimental studies using cyclic voltammetry, amperometry and IR spectroscopy, it has been concluded that PANI facilitates the oxidation of AA. It has been possible to achieve a maximum power density of 4.3 mW cm -2 at a load current density of 15 mA cm -2 at 70 ◦ C. As both AA and PANI are inexpensive and environmental-friendly, the present findings are expected to be useful for the development of cost-effective DAAFCs for several low power applications. Keywords: Ascorbic acid; Polyaniline; Electrooxidation; Fuel cell 1. Introduction In the context of fast depletion of fossil fuel resources as well as the increase in atmospheric pollution, research and development activities on batteries and fuel cells have occu- pied great importance in recent years. Among several types of fuel cells, polymer electrolyte direct methanol fuel cells (DMFCs) are being projected for a variety applications rang- ing from micro-power to mega-power [1–3]. This is primarily because of feeding of a liquid fuel to the anode in a convenient way. Rapid miniaturization of electronic devices and expan- sion of their utility are likely to demand for further potential applications of DMFCs. The attractive features of DMFCs are also due to a high theoretical energy density expected from methanol among several small organic molecules [4]. This is due to the transfer of six electrons per molecule during oxidation of methanol to CO 2 and H 2 O. Furthermore, a regenerative DMFC, which is based on the concept of electrochemical reduction of CO 2 to CH 3 OH and employing the latter as the fuel, sounds ∗ Corresponding author. Tel.: +91 80 22933183; fax: +91 80 23600683. E-mailaddress: muni@ipc.iisc.ernet.in (N. Munichandraiah). more interesting as this is also related to address the global warming problem [5]. Despite of the advantages and inter- esting aspects involved in using methanol as the fuel for electrochemical energy conversion, the electrocatalyst used for the oxidation of methanol plays a crucial role. The best catalyst known for this reaction is Pt–Ru alloy [6]. How- ever, for a wide-spread application of fuel cells, it is im- perative to employ a non-platinum metal catalyst for cost reduction. There are two approaches to handle the problem of re- ducing the usage of expensive platinum metal catalysts in fuel cells. One approach is to investigate alternate bi- or tri- metallic catalysts employing on transition metals, or modified conducting polymers [7]. The other approach is to investigate alternate fuels which can undergo oxidation on inexpensive catalysts [8]. In the latter approach, ascorbic acid (AA), which is a biologically important compound and inexpensive, is in- vestigated as the fuel in the present work. In comparison with methanol, AA is a solid, slightly more expensive and provides lower energy density. However, studies using AA as the fuel are interesting as AA is soluble in acidic aqueous solutions to make sufficiently concentrated solutions, and it can undergo electrooxidation on an inexpensive non-noble metal catalyst,