How to make fluorine?

You can't electrolyzed HF(aq) because the potential of water is much lower than that of HF. You would need to convert all your water to H2 and O2 before you could do the electrolysis with HF. Nevertheless, it is possible to produce F2(g) via electrolysis. H. Moissan (who won a nobel prize for such feat) did it using Pt/Ir electrodes with a mixture of 1 KF: 2 HF(l) where HF is anhydrous and where the temp is lowered to -24 degC to be brought to the liquid face. However, the oxidizing nature of F2(g) yielded an immediate combustion with the silicon grease used to seal the apparatus. Nowadays a sealed steel reactor is used and care is used to keep H2 and F2 separated because their reaction to form HF is very exothermic and as a result quite explosive. It does not seem that electrolysis in water is possible. My advice to you is that if you need F2(g), buy it from a supplier, the risk of explosion is to great.