Things are far more simpler.
The first Piantelli rod was fllled onto its SURFACE quietly by an H2 mix with H mono STABLES onto the nickel acting as a catalyst, so.
How ? Slowly hydrogen was deposited lowering the vessel internal pressure from a little bit under 1 bar to lower pressures.
When pressure was too low they refilled the vessel, again and again.
At the end , it could not be possible to load more the surface because almost all the surface was covered.
However it remained enough space between species to generate continually some H mono.
There was some hydrogen chains onto the surface like that : H2 space H space H2 space etc...Ina continualy way H was transfered from an H2 to another H alone and reverse etc etc..
This way inducting their xsh.
There are some methods of atomic hydrogen detection presented here.