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

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic production of hydrogen peroxide (H₂O₂) offers a sustainable alternative to energy-intensive methods like anthraquinone oxidation.
• Developing efficient and stable electrocatalysts is crucial for advancing H₂O₂ synthesis via the two-electron oxygen reduction pathway.

Purpose of the Study:

• To synthesize and characterize graphene-supported nickel single-atom (SA) electrocatalysts for enhanced H₂O₂ production.
• To investigate the catalytic activity, selectivity, and stability of Ni-SA catalysts for the two-electron oxygen reduction reaction.
• To elucidate the reaction mechanism and the role of isolated Ni sites using theoretical calculations.

Main Methods:

• Synthesis of graphene-supported Ni single-atom electrocatalysts via a surfactant-free reduction process.
• Electrochemical characterization including activity and selectivity measurements under alkaline conditions (pH = 13).
• Density functional theory (DFT) calculations to understand the reaction pathway and catalyst performance.

Main Results:

• The Ni-SA electrocatalysts demonstrated enhanced electrocatalytic activity and stability.
• High H₂O₂ selectivity (>94%) and mass activity (2.11 A mg_Ni^-1 at 0.60 V vs RHE) were achieved.
• The unique structure of isolated Ni sites, supported by oxygen functional groups on graphene, promoted the two-electron oxygen reduction pathway.

Conclusions:

• Graphene-supported Ni single-atom catalysts provide an effective platform for selective H₂O₂ production.
• The isolated Ni sites play a critical role in optimizing the electrocatalytic pathway for efficient H₂O₂ synthesis.
• This work presents a novel approach for controlling reaction pathways in atomically dispersed non-noble metal catalysts.