Role of Surface Area on the Performance of Iron Nickel Nanoparticles for the Oxygen Evolution Reaction (OER)

Abstract

Iron-nickel bimetallic electrocatalysts have recently emerged as some of the best candidates for the oxygen evolution reaction (OER) in alkaline electrolyte. Understanding the effects of composition and morphology of iron-nickel nanoparticles is crucial for optimization and enhanced electrocatalyst performance. Both physical surface area and electrochemical surface area (ECSA) are functions of morphology. In this study, three different iron-nickel nanoparticle catalysts were synthesized. The three catalysts were varied based on morphology (alloy versus core-shell) and composition (high versus low stabilizer concentration). Brunauer-Emmett-Teller (BET) surface area analysis was conducted on the synthesized iron-nickel nanoparticles using a physisorption analyzer while electrochemical impedance spectroscopy (EIS) was employed to quantify the ECSA by capacitance. Comparison of ECSA and BET results to electrocatalyst overpotential suggests both available surface area and nanoparticle morphology play roles in electrocatalytic activity.