  For its potential as a catalyst, nanoporous gold (NPG) prepared through
dealloying of bulk Ag-Au alloys has been extensively investigated. NPG thin
films can offer ease of handling, better tunability of the chemistry and
microstructure of the nanoporous structure, and represent a more sustainable
usage of scarce resources. These films are however prone to intergranular
cracking during dealloying, limiting their stability and potential
applications. Here, we set out to systematically investigate the grain
boundaries in Au28Ag72 thin films. We observe that a sample synthesized at 400
{\deg}C is at least 2.5 times less prone to cracking compared to a sample
synthesized at room temperature. This correlates with a higher density of
coincident site lattice grain boundaries, especially the density of coherent
sigma 3, increased, which appear resistant against cracking. Nanoscale
compositional analysis of random high-angle grain boundaries reveals prominent
Ag enrichment up to 77 at.%, whereas sigma 3 coherent twin boundaries show Au
enrichment of up to 30 at.%. The misorientation and the chemistry of grain
boundaries hence affect their dealloying behavior, which in turn controls the
cracking, and the possible longevity of NPG thin films for application in
electrocatalysis.
