in this configuration when aileron is up additional drag is created because of split.
Looking at the following picture taken from this NACA report, it can be seen that, the lift coefficient being the same, a split flap/aileron generates less drag than a plain flap/aileron, especially at high AoA:
So, with a split flap/aileron the opposite of what you'd like to achieve actually happens.
Also for the pitching moment similar results are obtained, with the split flap/aileron modifying the moment less than a plain flap/aileron, the $C_l$ being the same.
Both plain and split flaps/ailerons were superseded after WW2 by the more efficient slotted flaps/ailerons.
Spoilers are normally used to... well spoil the airflow on the upper surface of a wing, basically triggering a controlled stall.
Even if they can be termed spoileron and used as primary control surfaces (typical example is the B-52 and many, if not all, jet fighters), they shouldn't be confused with ailerons as such:
- aileron are deployed in a more or less asymmetrical way between left and right wing (one goes up and the other goes down); spoilers can only go up, locally reducing lift and increasing drag.
- ailerons end at the trailing edge of the wing and extend for some 0.2 chord; to be effective, spoilers are normally placed at a distance of some 0.6 chord from the leading edge and do not extend to the end of the wing.
- on the B-52 spoilers were preferred to ailerons due to aeroelastic problematics of the very elongated wing.