Will OH- ions be reduced or H+ ions be reduced in KOH electrolyte

I was trying to see if I can make a battery that uses KOH as the cathode electrolyte with platinum as the cathode electrode, but I got confused as to what gets reduced in this solution (Aluminum sulfate is the anode electrolyte and aluminum is the anode electrode).


$\ce{K+}$ never will get reduced because that is thermodynamically unfavored, so will $\ce{OH-}$ (from the KOH ion) get reduced to $\ce{OH^2-}$? It makes more sense to me that $\ce{OH-}$ gets reduced because KOH is very basic and there will be a ton of $\ce{OH-}$ ions that can go to the electrode and accept the electron. 
I just don’t know if this is favored thermodynamically or how I can calculate it.


Or will it be $\ce{H+}$ from water? Will water ionize in the first place? 


