I wont be able to provide Qur'anic evidence as im not taht learned. However, i know this much, depending on the school of Fiqh you follow (Shafi, Hanafi, Maliki or Hanbali) its 2+1 or 3.....but not 1 rakaah on its own (someone feel free to correct me)
I know that Shafi School of Fiqh pray 2...