Nanoporous Gold Thin Film: Fabrication, Structure Evolution, and Electrocatalytic Activity

Abstract

This paper demonstrates a new and simple approach to fabricate nanoporous structure on gold thin films (∼1.5 μm) via electrochemical alloying and dealloying reactions in ZnCl₂/DMSO electrolyte. The relevant parameters affecting the formation of nanoporous structure in the alloying/dealloying process in organic electrolyte and the post-treatment in sulfuric acid solution are investigated in detail by simultaneous electrochemical and field emission scanning electron microscopy (FESEM) characterization. Herein, a new strategy for direct estimation of the end-point in the dealloying process is developed, assuring the success of preparing nanoporous gold (NPG) films with the highest purity and porosity. Our method is especially useful for fabrication of nanoporous structure on ultrathin Au films without any further deposition of Au. The as-prepared NPG thin films are then used as anodic catalysts for borohydride oxidation in the direct borohydride fuel cell (DBFC), which show much higher catalytic activities in contrast to planar gold electrode, indicative of the promising applications in actual DBFC systems. We believe that our work offers a new route to solve the current problems encountered in the development of DBFCs.