> You need co2 scrubbers for any oxygen producing solution, since co2 kills faster than o2 scarcity.
Given their uses are the space station, planes and submarines, cant you just vent some of the atmosphere out since you're in a pressurized tube of some kind to lower the CO2?
It's far too expensive to launch new material up to do that. It's much better to scrub out the CO2 specifically than to throw out mixed gases. If you're just removing CO2 you only need to replace it with new oxygen which can be electrolicized from water stores but if you're tossing out cabin air in bulk there's stuff like nitrogen that's harder to replace. The ISS is basically sea level air with 21% O2 and the rest nitrogen plus trace CO2 and other gasses, that nitrogen would be much harder to replace.
With hydrolysis you just have waste Hydrogen to toss which could in the future be combined with CO2 from the scrubbers to create methane fuel (probably not in significant quantities but it closes the cycle on O2 as the Sabatier reaction also creates H2O which could feed back into electrolysis or drinking.
Given their uses are the space station, planes and submarines, cant you just vent some of the atmosphere out since you're in a pressurized tube of some kind to lower the CO2?