There's been a lot of work done on finding a way to safely and cost effectively store hydrogen. My favorite is lanthanum nickel metal hydride. Dramatically safe.

Of course, none of these methods are cheap or easy. So, I'm gonna try to change that. My plan is to take a regular steel tank, unscrew the valve, and pour a substantial amount of graphene infused activated carbon into the tank, then reseal the valve. Then, I'm going to hook up my vacuum pump and pull as much air as possible out of it. This is done for safety since you never want to compress oxidizer and fuel in the same container.

My theory is that the graphene, already presenting enormous surface area, will increase the already high surface area of the activated carbon. If you look at simulations of gas molecules they're flying around all over the place, bouncing into and off of each other and anything else. By combining the graphene and the activated carbon, it should make a highly convoluted 3D maze that the hydrogen can go into and settle, more of a nanomechanical than a chemical abode.