You Do Need power plug adapter while traveling from Central African Republic to Sierra Leone.

Here is Why You Need An Adapter

The outlet and plug type used in Sierra Leone are D and G and in Central African Republic are C and E. This is how they look like.

Central African Republic

In Central African Republic, outlets of type C and E are in use.

Type C

Type E

Sierra Leone

In Sierra Leone, outlets of type D and G are in use.

Type D

Type G