Hello,
Aymeric and I, we started a discussion some time ago about adding new prefixes to French Gregg. I had particularly in mind the prefixes hydr- and oxy-. For the prefix oxy-, it’s easy, the ideal prefix would be o/ as it isn’t used in French Gregg. For the prefix hydr-, well, I had a soft spot for id/ but finally, I settled for i/, it’s not ideal because it is already used for incl-… but it’s simpler and apparently, there is no risk of confusion.
So, here is an excerpt from « l’Architecture de l’Univers » by Serge Brunier… where the words oxygène and hydrogène are used.

Edited.