Graphene-Supported Single Nickel Atom Catalyst for Highly Selective and Efficient Hydrogen Peroxide Production

Hydrogen peroxide (H₂O₂) production by electrocatalytic two-electron oxygen reduction shows promise as a replacement for energy-intensive anthraquinone oxidation or H₂/O₂ direct synthesis. Here, we report on graphene-supported Ni single-atom (SA) electrocatalysts, which are synthesized by a simple surfactant-free reduction process with enhanced electrocatalytic activity and stability. Unlike conventional Ni nanoparticles or alloy catalysts, the well-dispersed Ni-SA sites lack adjacent Ni atoms. This structure promotes H₂O₂ production by a two-electron oxygen reduction pathway under an alkaline condition (pH = 13). This catalyst exhibited enhanced H₂O₂ selectivity (>94%) with a considerable mass activity (2.11 A mg_Ni^-1 at 0.60 V vs reversible hydrogen electrode), owing to the presence of oxygen functional groups and isolated Ni sites. Density functional theory calculations provide insights into the role of this catalyst in optimizing the two-electron oxygen reduction reaction pathway with high H₂O₂ selectivity. This work suggests a new method for controlling reaction pathways in atomically dispersed non-noble catalysts.