Donald's superhero alter ego comes from Italy and its original (Italian) name is Paperinik. The name itself is a play on the Italian comicbook anti-hero Diabolik
http://en.wikipedia.org/wiki/Diabolik (Donald's Italian name is Paperino). Likewise, Paperinik (or Duck Avenger or Phantom Duck or Superduck as he is known in other countries) was initially an anti-hero, using his alter-ego to exact revenge on his daytime oppressors, like Uncle Scrooge and cousin Gladstone.
In the original story, Donald finds the costume of Fantomius (an obvious Fantomas analogue) in a house he accidentally inherits, and decides to use it for non altruistic reasons, creating the identity of Paperinik. Eventually, the writers turned the character into a Batman-type superhero, even having him patrol the city at nights and facing criminal masterminds.
Are you remembering the Carl Barks 10-pager where Donald gets superpowers? If yes then the name was "Super Snooper" though I think the character was a favorite of his nephews.