Performance of Direct Formate/Sodium Persulfate Microfluidic Fuel Cells with Carbon Paper and Graphite Felt Electrodes

Microfluidic fuel cells (MFCs) are potential micro power sources for portable electronics. MFCs utilize the co-laminar flowing of the solutions in the microchannel and remove the membranes in the traditional fuel cells. Flow-through electrodes exploit the internal electrode surfaces and improve the MFC performance. Carbon paper (CP) has been widely used as a flow-through electrode with a limited specific surface area. We have also used graphite felt (GF) with a high specific surface area as the electrode and then compared the performance of the MFCs with the CP and GF as the electrodes, respectively. Firstly, we showed the SEM surface morphologies of the two electrodes with or without the Pd catalysts. Secondly, we compared the electrochemical activities of the two electrodes in the solutions, respectively. The GF electrode always showed higher electrochemical activities than the CP electrode, since the GF electrode owned its larger accessible electrochemical surface area and less electrode resistance than the CP electrode. Thirdly, we compared the performance of the MFCs with the two electrodes. The results showed that the performance of the MFC with the GF electrodes electrodes was optimum, with the peak power density of 175.60 mW cm⁻² and limiting current density of 616.53 mA cm⁻². Finally, we conducted the discharge performance of the MFCs with the two electrodes. There existed a minor variation in the discharge current densities of the MFCs with the CP cathodes.