Look in the Segoe UI Symbol font, mostly in the Private Use range starting at &E000
You can see most of the symbols with charmap.exe, although not all of the emoji show up. You should be able to see them all with Word's Insert Symbol option and there are some 3rd party apps which may help.
If you are using xaml then look in standardstyles.xaml for many predefined AppBar button styles to see of one already exists that matches your usage.
--Rob