Ammonia Electrooxidation Lab for the ISS

The AELISS is a miniaturized version of the Electrochemical Microgravity Laboratory (EML) comprised of two major components: the Electronic Rack (ER) and the Electrochemical Equipment Box (EEB)^{6 (link)–8 (link)}.
Ammonia Electrooxidation Laboratory at the ISS (AELISS) was inside a 2U Nanoracks module (NR-2U) of 4'' x 4'' x 8'' dimensions and connected to the ISS power rack via a USB-b port (5 V and 5 A). AELISS is comprised of two main parts: the electrical module and the electrochemical containers. The electrochemical containers are comprised of two sets of three-electrode electrochemical cell setup. The AP controlled the two peristaltic pumps that pumped the ammonia solution to the electrochemical flow cell and two sets of six (6) electrochemical experiments were run. AP provides a fixed potential to an electrochemical cell setup while it monitors the current as a function of time; this is a chronoamperometry experiment (CA). Afterward, on another electrochemical cell setup, the system controls a changing potential while it monitors the current generated (i.e. cyclic voltammetry (CV)). The electrochemical cell setup consisted of two sets of six screen-printed electrodes shown in Fig. 3. The working electrodes were modified with Platinum Vulcan catalyst ink^{9 (link)}. The electrochemical part is triply contained in order to avoid any unlikely leakage of diluted ammonia solution (0.05 M (NH₄)₂SO₄ in 0.18 M NaOH) following safety guidelines. This setup holds a maximum of 10 mL 0.05 M Ammonia solution at pH = 12.9. The experimental data was stored on a memory card. Figure 4 illustrates the closed Ammonia Electrooxidation Lab at the ISS (AELISS) device and Fig. 5 shows the open device picture of two sets of closed loops of ammonia solution inside the protective plastic frame and the closed device inside the Ziploc^® bag.Fig. 4

a Illustration of the closed AELISS device and b schematic Isometric view of the plastic protective frame with the electrochemical cells. The AELISS had a potentiostat and its plastic cover, plastic protector box frame, two electrochemical cell arrays, two screen-printed electrodes (SPE), two peristaltic pumps, and a storage device.

Fig. 5

a Open device picture showing the two sets of closed loops of ammonia solution inside the protective plastic frame and b the closed device inside the Ziploc® bag.