A dealloying process of core-shell Au@AuAg nanorods for porous nanorods with enhanced catalytic activity.

One-dimensional porous metallic nanomaterials have attracted much attention due to their unique shape and hollow structure. Herein, the gold nanorods in a porous shell of an AuAg alloy are synthesized via a dealloying process of the core-shell Au@AuAg nanorods at room temperature. The formation of tiny pores in the shell results in the huge red-shift, sharp decrease and drastic broadening of longitudinal surface plasmon resonance absorption. The continuous removal of silver from the porous nanorods leads to the breakage of tiny pores and leaves a rough surface on the nanorods behind. The rough surface gradually becomes smooth in the subsequent dealloying process. The surface structures of these intermediates are correlated with their absorption spectra and catalytic activities for the catalytic reduction of p-nitrophenol. The porous nanorods show a higher catalytic efficiency than the gold nanorods, the core-shell nanorods and the rough nanorods. The results indicate that the dealloying of anisotropic bimetal nanomaterials not only provides an effective pathway to carve the structures on the nanoscale but also offers numerous opportunities to observe novel optical properties and enhanced catalysis performances.