Synthesis of Nanoporous Gold Structures via Dealloying of Electroplated Au-Ni Alloy Films

We studied the synthesis of nanoporous gold (NPG) films using electrodeposited Au-Ni as a precursor for dealloying. Potentiostatic dealloying of amorphous Au-Ni (Ni 65, 77, and 85at%) films at 0.7VSCE in 10mM H2SO4, resulted in the formation of nanoporous structures with average pore diameter increasing with Ni content from 69 to 107 nm. Alloy films with high Ni content are more susceptible to surface cracking due to large internal stresses. Potentiostatic dealloying of amorphous Au-Ni 73at% at 1.0V, 1.3V, and 1.5VSCE in 10mM H2SO4 yielded NPG structures with an average pore size which decreased with increasing applied voltage, from 57nm to 36nm. At higher anodic potentials, surface cracks become more apparent. Finally, the NPG structure could be tuned also by potentiostatic dealloying of partially crystallized Au-Ni 73at% at 0.7VSCE in 10mM H2SO4. The average pore size measured about 9nm, much smaller than those observed in dealloyed amorphous Au-Ni films.