Unconventional Bilateral Compressive Strained Ni-Ir Interface Synergistically Accelerates Alkaline Hydrogen Oxidation

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The alkaline hydrogen oxidation reaction (HOR) is significantly slower than in acid media due to coupled adsorption of hydrogen (H_ad) and hydroxyl (OH_ad) species.
• The Sabatier principle highlights the need for electrocatalysts with optimal binding energies for both H_ad and OH_ad to enhance HOR kinetics, a persistent challenge.

Purpose of the Study:

• To design and investigate an unconventional electrocatalyst for efficient alkaline HOR.
• To explore the synergistic effects of a strained Ni-Ir interface on HOR activity and intermediate adsorption.

Main Methods:

• Density functional theory (DFT) simulations were employed to analyze the electronic structure and adsorption properties of the proposed catalyst.
• Experimental synthesis of the Ni-Ir interface by embedding sub-nanometer Ir clusters in graphene-loaded Ni nanocrystals (Ni-Ir(BCS)/G).
• Electrochemical characterization to evaluate HOR mass activity and CO tolerance compared to commercial catalysts.

Main Results:

• DFT simulations confirmed that bilateral compressive strain (BCS) optimizes H_ad and OH_ad adsorption, facilitating spontaneous and preferential coupling.
• The synthesized Ni-Ir(BCS)/G catalyst demonstrated a 7.95-fold increase in HOR mass activity compared to Ir/C and a 2.88-fold increase compared to Pt/C.
• The catalyst exhibited significantly enhanced tolerance to CO poisoning, a common issue in HOR catalysis.

Conclusions:

• The strained Ni-Ir interface acts as an efficient synergistic site for alkaline HOR, overcoming kinetic limitations.
• This work provides a new strategy for designing advanced electrocatalysts by controlling interfacial strain for coordinated reactant adsorption and activation.
• The developed catalyst represents a significant advancement in HOR catalysis, offering high activity and stability.