We report nanoporous Pd100–x Au x (x = 0, 25, 50, 75, 100; np-PdAu) bimetallic catalysts fabricated by electrochemically dealloying isomorphous Pd20–y Au y Ni80 (y = 0, 5, 15, 20) precursors. The chemical composition of the nanoporous bimetallic catalysts can be precisely controlled by predesigning Pd/Au ratios in the ternary alloys. Dealloying at an appropriate potential for each alloy can selectively leach Ni away while the Pd and Au remain intact to form a geometrically controllable nanoporous structure. The electrocatalysis of the np-PdAu shows evident dependence on the Au/Pd atomic ratio, and the np-Pd75Au25 bimetallic catalyst shows superior electrocatalytic performance toward ethanol electrooxidation in comparison with commercial Pt/C, np-Pd, and other np-PdAu alloys. Since there are no obvious geometric shape and pore size disparities among the np-PdAu samples, the dealloyed catalysts also provide an ideal system to explore the chemical origins of the excellent catalytic properties of bimetallic catalysts.

A novel nanoporous gold-palladium alloy has been successfully fabricated by electrochemically dealloying a multicomponent metallic glass. In comparison with conventional nanoporous gold prepared by dealloying Au-Ag alloys, the nanoporous gold-palladium alloy shows much higher catalytic activity for electrooxidation of methanol as a free-standing electrode. Moreover, a small amount of palladium in the nanoporous alloy is found to dramatically improve the electrochemical stability of nanoporous gold.

The practical applications of high-capacitance polypyrrole (PPy) as an active material for electrochemical supercapacitors are mainly limited by their poor cycling stability. By utilizing nanoporous gold enhanced Raman scattering of PPy, we investigated ex situ and in situ the structural origins of the low electrochemical stability of PPy. This study provided direct evidence that the stability degradation of PPy is caused by the irreversible transition between oxidation and reduction states of PPy, which is associated with the permanent deformation of PPy molecular chains subjected to applied potentials.