After being cut in half and put into a refrigerator overnight, will a potato retain its vitamins.

The potato will retain almost all of its nutrients if stored overnight in the refrigerator. Vitamin C is most susceptible to loss from exposure to air, but the loss overnight is minimal. To help retain nutrients, cover the cut surface or store the potato with the cut side facing down on a plate or in a storage container.

Here is a reference on vitamin C loss:  https://www.researchgate.net/publication/223473682_Vitamin_C_retention_in_fresh-cut_potatoes