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

Here is Why You Need An Adapter

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

Niue

In Niue, outlets of type I are in use.

Type I

Liberia

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

Type A

Type B

Type C

Type F