This question already has an answer here:
- Preserve cut potatoes 1 answer
After peeling potatoes and slicing them to your desired size, how do I store them away?
The main problem with storing pre-cut potatoes is oxidation, where they start to turn brown from contact with the air. To prevent this, store them submerged in water. You can get about 24 hours, refrigerated, in this manner.
This is is how restaurants that do natural cut fries store the pre-cut fries.
Would putting some lemon juice on the surface also work?
I know lemon juice is sometimes used on sliced apples... it works slightly differently by being oxidized itself rather than the apples.