In this answerthis answer I said:
In an emergency a pressurized tank of oxygen gas can be an immediate source of oxygen to pressurize the station, and (possibly) other thinks such as tanks for suits. But for a steady, lower rate supply of oxygen, electrolysis of plain old water works quite well, considering there is plenty of electrical power.
Is this how the various space suit air supply systems are provided with oxygen, now that NORS is the preferred method for oxygen transport and storageoxygen transport and storage on the ISS?
Is it mixed with other gases first, or do the suits use pure oxygen at reduced pressure?