As the person above mentioned, a question sentence is simply a question and it would be redundant otherwise.
However, it would not wrong to describe a sentence in such way.
For example, you can describe a sentence as being, as you have already said, interrogative or something similar like inquisitive. However, you would have to structure your sentence differently to avoid sounding weird.
As opposed to, "a negative sentence", you would have to say, "this sentence is inquisitive".