Effective and low-cost platinum electrodes for microbial fuel cells deposited by electron beam evaporation

A microbial fuel cell (MFC) is a device that converts chemical energy to electrical energy through the catalytic reaction of microorganisms. In this paper, electricity generation was investigated in microbial fuel cells using e-beam deposited Pt electrodes to improve efficiency and minimize Pt loading. We deposited Pt on carbon paper electrodes using an e-beam evaporator and imaged microscopic structures of the Pt deposited electrodes using scanning electron microscopy and atomic force microscopy. Although the e-beam electrode had the least thick Pt layer (1000 Å) among many tested electrode types (Pt-black = 1500 Å and commercial electrode = 2500 Å), it showed excellent coverage and Pt uniformity, resulting in minimal loading of Pt. In MFC testing, the e-beam Pt electrode installed only on the anode (carbon paper electrode on the cathode) produced the highest peak value of 0.42 A/m2 in the current density, which was about 2 times higher than when the Pt-black anode electrode or E-Tek commercial Pt anode electrode was used. After 45 h of microbial fuel cell running with the Pt electrode on the anode, the carbon electrode on the cathode was also replaced with an e-beam electrode. This replacement generated an immediate rise in current density, reaching a second peak of 0.50 A/m2. Considering the mass-specific current density, which represents the current density per unit Pt thickness, the e-beam electrode was the most effective with minimal Pt loading. The mass-specific current density for the e-beam electrodes was 2.5 times higher than that for the E-Tek commercial electrodes. These promising results suggest the high potential of e-beam-deposited Pt electrodes in improving microbial fuel cell efficiency with minimal Pt loading.