that would be cool, but wouldn't something simpler like electrolysis of water into hydrogen/oxygen work much better?
I haven't the effort to do the math, but it would require less steps, less complexity, and less cutting edge catalysts with unknown lifetimes
It's hugely inefficient, so it requires more solar power.
Hydrogen is hard to store and use; unlike propane, it penetrates through plastics and even metals. Hydrogen is a good rocket fuel if you need top performance and cost is no object.
Propane is very convenient, and can be reused across the existing LNG infrastructure.
Hydrogen is very difficult to use as a direct fuel source. This recent video gives a good overview of all the challenges a hydrogen engine has to overcome: https://youtu.be/DGL5g91KwLA
