Sorry, I should have mentioned water. But that bond is very strong, and the methods of breaking it are thus very poor. Another compound worth mentioning is amm

Sorry, I should have mentioned water. But that bond is very strong, and the methods of breaking it are thus very poor. Another compound worth mentioning is ammonia. A lot of the current hydrogen harvesting research revolves around ammonia. Unfortunately, ammonia is very scarce in nature and certainly soon exhaustible as a global fuel.