Your best bet for archival mounting is Whole Wheat Starch, which if properly made is devoid of "food stuffs" that microbes like, because it is repeatedly cycled until no mold or fungus will grow into it in solution with clean H²O.
Good Art Paper Supply Houses should have this in stock.
It's reversible.
The second archival choice I suggest, is a two to three part process.
Golden Paints Flat Gel/Paste medium to adhere the photographs to a prepared ground.
While my preference is for 200% Cotton Rag Board of eight (8) ply thickness, boards, plate glass and rust free metal plates also treated first with several coats of Golden's GAC 400 or GAC 800 acrylic medium.
Look at their work on stopping harmful gas passage through boards, canvas, papers that damage paintings, etc and double check which GAC Mediums they found to block these gases.
After applying several layers of medium, use Golden Acrylics White or Black Acrylic Gesso to create a ground for receiving your photographic work and use the flat medium as your adhesive.
It does not hurt to use the "outgassing prevention" medium first on the back of your printed pieces, but be aware that acrylic mediums are 'wet' to a degree that will warp papers, if not lightly pressed by a weight sufficient to keep the material flat while curing.
This is what I've used for linen covered boards and it is a sound practice so far as I've seen the last decade or so.
Good luck and show us your final work, if you please.
Eli