MOF.

This is coolbert:

"Image courtesy of  CSIRO."

Thanks to the input from WIZARD and Harry at Sharkhunters:

"AUSSIE CRYSTALS –   Carbon dioxide scrubbers: The Australian national science agency CSIRO is teaming up with engineering services company QinetiQ on a project that aims to provide better conditions for sailors through the use of advanced crystal technology called Metal-Organic Frameworks (MOFs). As submarines are an enclosed space, CO2 expelled by the crews’ breathing and other chemical processes builds up and can eventually become toxic."

"Scrubbers" as they are called for Australian diesel/electric boats. "Scrubbers" to absorb CO2 and prevent an potential dangerous build-up of carbon-dioxide in the submarine. Lessening the time spent near the surface snorkeling and replenishing oxygen supplies and purging noxious gases. Allow for a more healthy working environment.

Measures to maintain a suitable and "healthy working environment" in a submerged vessel often gone awry. Read here and here of such instances. Oxygen candles what they are called on occasion even more danger to the submarine than a foul atmosphere.

coolbert.