That's why I'm currently quite fond of platinum as a speculative investment. Fuel cells require quite a bit of platinum. Yet platinum has rarely been cheaper relative to other commodities like gold. I think because the market is discounting a decline in diesel engines and maybe because of recycling. (Even though platinum has been more expensive than gold even before catalysts were common.)
In addition, platinum deserves to receive a geopolitical risk premium. 80% of the world's platinum is mined (at a loss!) in South Africa, which is prone to intense labor disputes and looking less attractive every day. And the next big producer is Russia. Yet above ground stock piles have declined in the past decade.
In the 1+ year that I've been in platinum, it hasn't been a success. The market just remains comatose. But we'll see :-)