I'm not an expert in these metals
All I can say is that palladium likely has a lot wider use in industry (for example, car making) than the other precious metals. This metal is known for its extremely high absorption capacity of hydrogen. This property allows to use the metal as a medium for efficient and safe hydrogen storage. Indeed, it may be not as efficient as liquid hydrogen itself, but I don't think many people would want to drive a car which can easily turn into a sort of "hydrogen" bomb, especially after someone actually gets blown up
Using Palladium for the storage of Hydrogen can be terribly expensive. Because it may require many ounces of Palladium, just to store enough Hydrogen to power the vehicle for 200 or 300 km. And considering the remaining Palladium reserves around the world, I have to say that they may be enough for only a few thousand vehicles at the most
I basically agree with that
But it is the same with lithium if we talk about all-electric cars. Lithium is also rather rare to support millions of electric cars. Nevertheless, palladium can still play a few important roles in the future car, i.e. not only as a hydrogen "fuel tank", but also as a catalyzer. In the not too distant future, we could fuel our cars with pure water, then split water molecules into hydrogen and oxygen with a palladium catalyzer, and then use this metal as a safe hydrogen storage medium. I guess we wouldn't actually need many ounces of it, just enough to keep the cycle going
