Question

Does diffusion require oxygen?

Answer 1

Nope.

Explanation:

Diffusion is basically the net movement of particles down a concentration gradient, i.e. they will move from a region of higher concentration to a region of lower concentration. Such examples include carbon dioxide and oxygen.

However, the process itself does not require oxygen, as this process I would say is caused by the fact that all things in the universe want to reach a point of equilibrium.