A 3D-printed lab scale 3-electrode holder for zero-gap electrode configuration

Electrolysis is one of the most promising technologies for green hydrogen production, and extensive research efforts are devoted towards discovering new active and stable catalyst materials, as well as developing novel porous electrode structures for both the anode and cathode. However, most lab-scale catalyst testing is performed in either rotating disk electrodes or beaker-type cells that hardly reflect the operating conditions in a technological electrolyzer. In this work, we provide a 3D-printable cell holder design that allows for lab-scale testing under zero- or controlled-gap electrode configuration while supporting the placement of a reference electrode in the middle of the separator. Polypropylene (PP) or high-performance thermoplastics like polyetheretherketone (PEEK) can be used as filaments, depending on the application. 3D-printing of the cell results in material savings of 70%, thereby reducing material waste and environmental impact. We demonstrate the holder in both zero-gap and controlled-gap configurations, assessing data quality and reproducibility, using Fe-free Ni electrodes in alkaline electrolysis as a test case. Furthermore, the holder was demonstrated for longterm stability tests of 250 h at 60 °C by applying a fixed current density of 500 mA/cm. The design is freely available for download as a CAD file.