You Do Need power plug adapter while traveling from Burkina Faso 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 Burkina Faso are C and E. This is how they look like.

Burkina Faso

In Burkina Faso, 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