Bulk hierarchical nanoporous palladium prepared by dealloying PdAl alloys and its electrochemical properties

Abstract

Bulk hierarchical nanoporous palladium (BHNPP) materials composing both bimodal porous structure and monolithic porous structure were fabricated by chemical dealloying of Pd20Al80 alloy with sub-micrometer grain size via mechanical alloying and spark plasma sintering process (MA-SPS). The different nanoporous structures were formed in the regions where the microstructure was heterogeneous. Monolithic porous structure were formed after dealloyed of monolithic grain structure mainly composed of PdAl3 phase, and bimodal porous structure with both larger pore of hundreds nanometers and smaller pore of a few nanometers were obtained after dealloyed of nanocrystalline structure consist of PdAl3 and Al phases, respectively. Effects of dealloying time, concentration of dealloying solutions and chloride ion (Cl−) on the evolution of the microstructure of BHNPP were also studied. Ligament of BHNPP can be facility coarsen by add chloride rather than only raise the concentration of HCl solution. Moreover, the cyclic voltammetry results reveal that the BHNPP materials have superior ethanol oxidation ability.