Dealloying behavior of Mn–30Cu alloy in acetic acid solution

•The concentration of acetic acid solution strongly affects the dealloying process.•The concentration of acetic acid solution has a key effect on microstructure of NPC.•The nanopore formation rate rises firstly and then falls with solution concentration.•The change is caused by competitive effect between association and ionization.•The concentration of H+ in acetic acid solution is evaluated by calculation. The dealloying behavior of single-phase Mn–30Cu sheets in acetic acid solutions with varying concentrations ranging from 1vol.% to 60vol.% and morphological evolution of nanoporosity have been investigated. The results show that the concentration of acetic acid solution has a key influence on the dealloying process and microstructure of nanoporous copper. It can be well explained as a consequence of the competition between association and ionization of acetic acid molecules. Additionally, the formation rate of porous structure in organic acid solution is remarkably lower than that in inorganic acid due to the limited H+ concentration from the competitive effect.