You Do Need power plug adapter while traveling from Liberia to Mauritania.

Here is Why You Need An Adapter

The outlet and plug type used in Mauritania is C and in Liberia are A, B, C and F. This is how they look like.

Liberia

In Liberia, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F

Mauritania

In Mauritania, outlets of type C are in use.

Type C