Enhancement of hydrogen production in a single chamber microbial electrolysis cell through anode arrangement optimization

► The optimization of anode arrangement is effective to reduce the inner resistance of microbial electrolysis cells (MECs). ► Separately placing the anodes on both sides of the cathode improved the current and hydrogen production rate of MECs. ► A maximum current density of 1355A/m3 with a high hydrogen production rate of 10.88m3/m3d can be achieved. ► Modifying the anode into stacking mode made the polarization and biofilm resistance of MEC decreased by 35% and 78%. Reducing the inner resistances is crucial for the enhancement of hydrogen generation in microbial electrolysis cells (MECs). This study demonstrates that the optimization of the anode arrangement is an effective strategy to reduce the system resistances. By changing the normal MEC configuration into a stacking mode, namely separately placing the contacted anodes from one side to both sides of cathode in parallel, the solution, biofilm and polarization resistances of MECs were greatly reduced, which was also confirmed with electrochemical impedance spectroscopy analysis. After the anode arrangement optimization, the current and hydrogen production rate (HPR) of MEC could be enhanced by 72% and 118%, reaching 621.3±20.6A/m3 and 5.56m3/m3d respectively, under 0.8V applied voltage. A maximum current density of 1355A/m3 with a HPR of 10.88m3/m3d can be achieved with 1.5V applied voltage.