Improved activity and stability of Ag-Rh network-like nanoalloy as support-free electrocatalyst for oxygen reduction in alkaline fuel cells

Abstract

In this study, a simple and environmentally amicable synthesis procedure for support-free silver-rhodium (Ag-Rh) bimetallic network-like nanoalloy was used to catalyze an oxygen reduction reaction in an alkaline medium. The support-free network-like morphology of Ag-Rh nanoalloy exhibits a higher electrochemical surface area (ECSA) of 65.6 m2/g than carbon (VC) supported Ag-Rh (23.8 m2/g). In comparison to the reported benchmark Ag-based electrocatalysts, it presents an improved mass and specific activity of 971.1 mA/mg and 1.45 mA/cm2, respectively. Based on the durability test, the support-free Ag-Rh catalyst retains ∼70% of its initial ECSA after 7000 potential cycles, and Ag-Rh/VC possesses only 20% after 5000 potential cycles due to the surface oxidation of carbon support. Hence, the superior electrocatalytic performance attributed to the support-free morphology and alloy formation with Rh was clearly demonstrated, which could potentially be the choice of the cathodic electrocatalyst for alkaline fuel cells.