Potent Noble Metal–Nickel Oxide Interaction: A Strategy for Improved Oxygen Reduction Reaction via Engineering the Electronic Structure

Abstract

Design of both efficient and durable electrode materials is key for oxygen reduction reaction (ORR) in influencing the efficacy of both fuel cells (FCs) and metal-air batteries (MABs). Here, we demonstrate the uniform dispersion of noble metals like (Au), palladium (Pd), and platinum (Pt) on nickel oxide on nickel electrodes (NM@NiO|Ni) for promoting ORR under alkaline electrolytes through engineering the electronic structures of noble metals as active sites. The NM@NiO|Ni electrodes are fabricated using acid etching followed by the galvanic replacement reaction method. Nickel oxide functions as an appropriate and encouraging support that can intensely interact with noble metals for both high catalytic activity and stability improvement. The Pd@NiO|Ni electrode exhibits prominent electrocatalytic ORR performance with an onset potential (E onset ) of ∼0.98 V [vs. reversible hydrogen electrode (RHE)], reduction potential (E) of ∼0.88 V (vs. RHE), catalytic cathodic current density of ∼−0.125 mA cm −2 at ∼0.88 V (vs. RHE), and mass activity of ∼0.38 Ag −1 in 0.1 M KOH, among the other developed electrodes in this study. The introduction of Pd as a second constituent to the NiO nanostructures enhanced the ORR performance expressively. The synergistic effects of Pd and Ni seem to possess a key impact on both catalytic ORR activity and stability. This strategy for enriching the catalytic active sites and the durability of the electrocatalysts demonstrates great potential for FC and MAB applications.