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 anthraquinonoid oxidation or H2/O2 direct synthesis. Here, we report on graphene-supported Ni single-atom electrocatalysts, which are synthesized by a simple surfactant-free reduction process with enhanced electrocatalytic activity and stability. Unlike conventional Ni nanoparticle or alloy catalysts, the well-dispersed Ni single-atom 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 mgNi-1 at 0.60 V vs. RHE), 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.