Ag-Cu Bimetallic Nanoparticles as Efficient Oxygen Reduction Reaction Electrocatalysts in Alkaline Media.

The alkaline medium oxygen reduction reaction (ORR) activities of Ag-Cu bimetallic nanoparticles (BNPs), consisting of neighboring Ag and Cu domains, were studied and compared with those of pure Ag and Cu nanoparticles prepared by the same polyol route. Three variations of Ag-Cu BNPs viz. Ag-Cu (4:1), Ag-Cu (2:1), Ag-Cu (1:1) BNPs were considered. The electrocatalytic performances of these nanoparticles were investigated by using different techniques, such as cyclic voltammetry (CV) and linear sweep voltammograms (LSV). The Ag-Cu bimetallics demonstrated synergistic ORR electrocatalytic activity compared to pure Ag or Cu. Optimum values of these parameters were observed for Ag-Cu (4:1) BNPs. According to LSV, the reduction peak position is at lower applied potential and showed higher intensity for the Ag-Cu (4:1) as compared to Ag-Cu (2:1) and Ag-Cu (1:1) BNPs. Density Functional Theory (DFT) calculations show that charge transfer from Cu to Ag (in the bimetallic nanoparticles) results in their stronger oxygen interaction and water activation properties relative to that of pure Ag nanoparticles.