I have a basic install of Xfce.
I also can open a new session with only i3.
Install nitrogen
sudo pacman -S nitrogen
It will repalce the background, for the wallpaper.
I don’t know what I’m currently using for my current setup with i3,
but it’s not nitrogen.
Remove Xfce wm
Go to session & startup.
on the second tab you have to set i3 at startup.
on the third tab, select never for xfwm4 and xfcedesktop.
And remove all shortcuts in xfce, because you gonna have some problems with thoses of i3.
And reboot.
And voila
