Interesting concept. I had sort of been bouncing the concept of a “photolithographic well” nanostructure off the walls of the inside of my head for a few days now. I think the “structure” has to be bigger than a single “H” (or “D”)....at least two and likely more, with means for ingress and egress of fuel and reactant products. A “sheet” of such structures fabricated on a high-thermal conductivity substrate should seriously boost heat transfer efficiency, and minimize size/power output. Probably would enhance controllability also.
My candidate for the anode is one of those iron hydride anodes in current use in high energy (or long life) rechargeable batteries.
Almost needless to say my wife has said NO to any table-top experiments with rigging them up to any sort of hydrogen gas feed.
She said "You are not allowed to blow us up"