Probing the effect of combustion controlled surface alloying in silver and copper towards ORR and OER in alkaline medium

Abstract

Bi-metallic silver-copper nanoparticles were synthesized using two modes of combustion synthesis, known as Solution Combustion Synthesis (SCS) and Second Wave Combustion Synthesis (SWCS) to enhance surface alloying in Cu and Ag. The alloying in Ag and Cu nanoparticles was found to affect the adsorption of the oxygen molecule and synergistically increases the relative activity towards ORR and OER in 1M KOH medium. The catalyst sample AgCu-21, synthesized by the SWCS showed highest activity and stability due to high concentration of Ag-Cu alloy on surface as verified by XPS, TEM and phase mapping of elements on the surface. The ORR catalyzed by AgCu-21 proceed through an overall four-electron pathway with a kinetic current density of 12.4mAcm−2 at −0.2V potential. The XPS analysis of the samples indicates that the ORR and OER activity correlate well with the shifting in binding energy of Ag on Cu surface with higher degree of alloying resulting in better electrocatalytic performance.