Unicode from Emoji not showing on push notification

I can show push notifications in plain text (using UTF-8 encoding), but the same emoji show up as Unicode characters in push notifications. ie: "\ ud83d \ ude0a" This is the SMILE EMOJI code that appears as Unicode characters in the push notification. Ps: I am using Firebase to send push notifications. Is there something else in the code or server side.? Any help would be appreciated.