Ag‐Decorated Reduced Graphene Oxide: An Electrocatalyst for Oxygen Reduction Reaction Applications in Alkaline Medium

Abstract

The oxygen reduction reaction (ORR), an electrochemical reaction at cathodes taking place in energy conversion and storage devices such as fuel cells and metal‐air batteries, plays a pivotal role. This study investigates the ORR activity of silver nanoparticles (AgNPs) integrated over reduced graphene oxide (rGO) in an alkaline medium. Compared to bare rGO, Ag x /rGO nanocomposites with varying loading of Ag show better ORR activity in an alkaline solution. Excellent performance is demonstrated by the Ag 40 /rGO nanocomposite (40% loading of Ag by weight) in terms of high limiting current density (–9.2 mA cm −2 @1600 rpm) and onset potential (0.86 V vs. reversible hydrogen electrode), high electrochemical surface area (33.2 m 2 /g), and lower Tafel slope value (55.19 mV dec −1 ). The nanocomposite Ag 40 /rGO demonstrates excellent stability, retaining 89.2% and 75% of current after 1000 and 5000 cyclic voltammetry cycles, respectively. Enhancement in the electrochemical performance of the optimized catalyst (40% of Ag) is attributed to the increased specific surface area and electrical conductivity due to the incorporation of AgNPs, which also act as spacers, preventing graphene sheets from restacking and minimizing the electrode degradation. This work opens new paths to future strategies toward tailoring the surface activity of non‐noble metal catalysts to enhance the sluggish ORR kinetics.