The Nobel prize website says he won the prize (which he shares with two others) for “the development of metal–organic frameworks.”

Here’s the wiki page for the frameworks: https://en.wikipedia.org/wiki/Metal–organic_framework?wprov=sfla1

And an excerpt relating to how they can be used:

MOFs are of interest for the storage of gases such as hydrogen and carbon dioxide. Other possible applications of MOFs are in gas purification, in gas separation, in water remediation, in catalysis, as conducting solids and as supercapacitors.