
105Microbial Fuel Cells and Other Bio-Electrochemical Conversion Devices
the traditional water electrolysis, which generally needs a voltage input
about 1.8–2.0 V.
A typical two-chamber MEC structure is shown in Figure 2.12. MECs
function in a similar mode as an air-cathode MFC, except that hydrogen is
generated at the cathode instead of water, and an external power source is
added. A membrane (either cation or anion exchange membrane, or gaseous
diffusion membrane) is essential for most MEC to prevent hydrogen from
diffusing back to the anode. In some cases, single-chamber MECs without
membrane may also be used to minimise energy losses [13