Inventor develops ‘artificial gills’
Someone came up with a way to “squeeze” oxygen directly from seawater. Though they say that it would be useful for SCUBA divers, I think it will be a long time before this gets adopted, if ever. Replacing a relatively simple device (a compressed air tank) with an electro-mechanical device that relies on batteries to operate is definately not something most divers (including myself) will be keen to do.
That said, it sounds like it could be of great use to submarines and underwater habitats, where it would be pratical to add filters (in the case of polutants in the water) and keep compressed air cylinders as backups. Divers can be a bit fanatical about their life support devices..