There are perfectly good industrial electrolysis cells that can split water with 85% efficiency, and that does not require platinum, only nickel (and by that I

There are perfectly good industrial electrolysis cells that can split water with 85% efficiency, and that does not require platinum, only nickel (and by that I mean elemental nickel, not nickel-molybdenum-nitride). They need to be big and operate under high temperature and use sodium or potassium hydroxide in the water, so for industrial purposes only, but essentially a solved problem. The unsolved problem is a good catalyst for the reverse process that takes place in hydrogen fuel cells. For that platinum is currently required, and no alternatives are known. I have read dozens of reports of catalysts for electrolysis, but not a single one for a replacement catalyst in hydrogen fuel cells. That would actually be a breakthrough. Even with the latter problem solved (where I'm optimistic), the problem of storing hydrogen in an efficient way is way harder, and there I'm less optimistic. For that reason alone I'm very sceptic to how realistic a hydrogen economy is.