Thickness 0.002-0.004 inch. A suitable material would be microporous, to give high specific surface area. Absolute porosity is less important - around 30-50% would be reasonable. My application does not require convective flow through the pores, so it is rather different from most porous-metal...
I am interested in porous foil. Realizing that this is likely a non-standard product, I expanded my question to include sheet. A google search for porous nickel comes up with plenty of scientific references, but lean on links to actual sources.
If you're interested, I can recommend several academic publications on the topic. You're right, the information is somewhat sparse.
Rob Broekhuis - broekhrr@apci.com