3D printed anode electrodes for microbial electrolysis cells

Microbial electrolysis cells are used to produce high purity hydrogen from organic wastes. Electrodes are one of the most important components of microbial electrolysis cells because they may directly affect the system performance. Moreover, these electrodes are costly and may negatively affect electrolysis performance by giving chemical reactions with organic wastes. This study uses cheese whey wastewater as electrolyte, and a two chambered microbial electrolysis cell with novel different shaped 3D printed anode electrodes. To improve mass transfer inside the cell, 3D designed, and printed electrodes are used in different geometries (rod, 1-cycled spiral, 2-cycled spiral, 3-cycled spiral, and 4-cycled spiral) by using cupper-based Electrifi filament. Electrochemical performance of the electrodes is observed by cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy analysis. As a result, it is observed that the organic content of waste and electrode geometry directly affects the microbial electrolysis performance and hydrogen production. In the electrochemical analysis, 1-cycled spiral geometry has up to 2.6-fold higher current density in linear sweep voltammetry analysis. In addition, in the hydrogen production measurements, 1-cycled spiral geometry is 5-fold faster than other electrodes. It is observed that spiral shape of the electrodes improves the contact region between the electrode and electrolyte interface, and the charge transfer performance.