You Do Need power plug adapter while traveling from Niger to Dominican Republic.

Here is Why You Need An Adapter

The outlet and plug type used in Dominican Republic are A, B and C and in Niger are C, D, E and F. This is how they look like.

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F

Dominican Republic

In Dominican Republic, outlets of type A, B and C are in use.

Type A

Type B

Type C