Nanostructure formation and D retention in redeposited-like W exposed to linear plasmas

•Amorphous and porous W layers where exposed to divertor relevant D plasma in PSI-2.•New shape of nanostructures (string-like) is found using amorphous W.•The presence of a porous morphology hinders the formation of surface nanostructures.•After exposure, nanostructures appear in general with a fluence threshold of 3–5 1025 D/m2.•D retention is enhanced by the presence of amorphous structure and open morphology.