MFC configuration
A single-chamber air-cathode MFC was constructed as previously described . The anode electrode was made of carbon cloth (without wet proofing; E-TEK, USA), and the cathode was made of carbon cloth (30% wet proofed, ETEK,USA) containing a Pt catalyst. The air-facing side of the cathode was coated with four PTFE diffusion layers as previously described (Cheng et al. 2006a). The electrodes were placed on opposite sides of the cylindrical chamber (4 cm long, 3 cm diameter; 28 mL liquid volume). Titanium wire was used for the connection of the external circuit to the carbon electrodes.