Structural tuning of nanoporous metal via electrodeposition

Nanoporous metal, fabricated via the selective dissolution of an alloy (i.e., dealloying), can be filled with another metal via electrodeposition to create unique, functional structures unattainable via just dealloying. In this work, by controlling the charge of Ni deposition, we finetune the porosity and the pore width of nanoporous copper. At a sufficiently low rate, the deposition proceeds uniformly under interface control, until the porosity approaches a percolation threshold, which also governs the smallest attainable pore width. Via microscopic characterizations, we determine that we can tune down the porosity from 57.5% to 15.8% and the pore width from 89 nm to 35 nm, while retaining the structural bi-continuity. The tuned structure rejects 80% KCl from a 1 mM solution, a function not available in the pristine structure but enabled by the narrowed pores.