You may be able to use an inner of a double chainring,
though Surly's Stainless steel chainrings are very nice.
[that's what I used on my Rohloff Hub bike]
Older pre index chainrings may work .. its the rampe and shifting aides you want to avoid.
chain .. match the cog on the hub .. 3/32" or 1/8''
single speed chains don't need the short flush pins that derailleur chains have featured
you can use a wider 1/8" chain on narrower 3/32" chainrings