Hi @fixit7, there sure is.
On the launcher: Right-click -> Properties
Now click on the icon upper left and a dialog opens to select what you want.
I’ll offer a little hint when you create or edit a launcher. If you want Thunar’s icon, type thunar (and only “thunar”) in the command field and it will go grab it for you. Once it’s there, put your bash script command back in.
Hope this gets it.