My question is that can one recite Durood while impure? Or Salawats? Is there any hadith or Ayah (verse) regarding that?
بسم الله الرحمن الرحیم
As you asked regarding reciting Durood or Salwat:
My question is that can one recite Durood while impure?Or Salawats
The answer could be considered as "yeah". Actually apparently you are allowed to recite Durood or Salavat during you are impure (Haidh or Jonob (wet dream) or ...)
In truth, in such positions it seems that the limitation is related to the reciting the holy Quran for those four Surahs which are WAjib-al-Sajdah (which have Wajib or obligatory Sajdahs(prostrations). Otherwise you are allowed to recite the rest of the Quran beside the Salavat as you inquired.
Purity, being in a state of Wudu (tahara) is not a condition of reciting the Quran and by greater reason of anything else like the Durud. There is a prohibition of touching the mushaf (Quran) while in a state of najasa (impurity), which is not permitted according to the verse in Surah Al Waqi'ah:
And none may touch it except the pure (Al Waqi'ah ayah 79)
Although some scholars interpret this to mean that the verse applies to disbelievers, and that Muslims may touch the mushaf while junub (impure), but the majority view is that the mushaf may only be touched by someone in a state of tahara.
As the answer above mentioned, reciting a verse of prostration from the Quran requires prostration, which has the condition of tahara, for those that consider prostration as a wajib (obligatory act), but this applies only to the verses of prostration, which again according to the majority are 15 in total , not other verses of the Surah's that contain them.