In the book, The Martian, I know that the oxygenator cools the air in the hab to separate out the gases. Then it somehow splits CO2 to get oxygen. What mechanism does it use to split the CO2?
From the page 231 of the book:
It heats CO2 to 900°C, then passes it over a zirconia electrolysis cell to yank the carbon atoms off.
Thanks Sean Duggan for pointing me to NASA's 2020 Mars mission tech, which includes MOXIE, an experiment in doing the same thing. It works via:
MOXIE uses a solid oxide electrolysis (SOXE) stack developed by Ceramatec, Inc. for converting CO2 to O2. Its working elements are stacked scandia stabilized zirconia (ScSZ) electrolyte supported cells with thin screen printed electrodes that are coated with a catalytic cathode on one side and an anode on the other.