QRD diffusor as sound sidewall? Size?


I am thinking about to DIY a pair of QRD diffusors to use it a side wall, separating my listening space and the kitchen area in the living room. The speakers are 10cm back to the wall because it is a kind of what sounds best like that (acoustic foam is planned to set behind). Cube Audio Nenuphar Minis. It`s a small place I know. The height of the room is 2.3m (7.6foot). The length is 3.1m (10.1feet).The space between the speaker is 1.6m (5.2foot).
Is it a good idea to have a QRD as side walls? What size would good? The max size what I can fit would be around 1.2-1.5m /4-5foot) tall, 30-35cm (12-14") deep and 1.1m (3.6foot) long. I was also thinking about to DIY bases under and use it as bass traps, but I don`t have much problems with bass, just around 400hz. 
128x128korakotta
The kitchen is next to the speakers. I have a dividing wall already set on the left side which separates the living room and the system from the kitchen. At the right side its about 2m empty space to the door and an LP shelf in the corner. I need a dividing wall on the left, a QRD or an absorber and I thought It would make sense to have the same wall on the right. I could replace the LP shelf with a large wall but then it would be asymmetrical. I have seen some using QRDs on the first reflection points, but because of the size limits may be to absorb would be the best. What kind of construction would you recommend? Combo panel?
If you mean that one side is a wall and the other side opens into your kitchen you should absorb on the side wall not diffuse. The open space into the kitchen acts like an absorber since sound get in there and gets "lost" and doesn't return to the listener. You would want to mimic this on the side wall which would be absorption. 

If you mean a regular room with 3 walls and the kitchen behind you... I have heard of people doing both absorbing or diffusing or a combo panel. I think in a room your size it may be best to absorb to control reflections.