Crack Mitigation during Dealloying of Au₂₅Cu₇₅

The suggested use of nanoporous gold for functional and structural applications requires uniform and specifically crack‐free monolithic bodies, ideally with a structure size in the range of 10 nm or below. Here we investigate electrochemical dealloying of two different starting alloys, Au₂₅Ag₇₅ and Au₂₅Cu₇₅, as pathways towards that goal. With an emphasis on the processes that lead to crack formation, we discuss the role of the parameters (i) lattice parameter change, (ii) dealloying potential and rate, and (iii) thermo‐mechanical treatment of the master alloys. The Cu‐based alloys are found to give superior homogeneity at very small structure sizes, provided that intermediate temperature treatments are avoided. A complete suppression of crack formation was achieved by application of a dealloying potential of 1.1 V versus Ag/AgCl, at a ligament size of 11 nm.