Iridium Single-Atom-Modulated Nickel Hydroxide for Boosting Overall Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for industrial water electrolysis.
• Existing catalysts often struggle with activity and stability at high current densities.

Purpose of the Study:

• To create a facile one-step hydrothermal method for fabricating a novel bifunctional electrocatalyst.
• To investigate the structural and electronic properties of single iridium atom-modulated nickel hydroxide nanosheets for water electrolysis.

Main Methods:

• A one-step hydrothermal synthesis strategy was employed to prepare Ir single-atom (SA)-modulated ultrathin nickel hydroxide nanosheets on nickel foam (Ir-Ni(OH)₂/NF).
• Density functional theory (DFT) calculations were used to understand the catalytic mechanisms and electronic structure.
• Electrochemical performance was evaluated for HER and OER in alkaline media.
• An anion exchange membrane water electrolysis (AEMWE) cell was assembled using the developed electrode.

Main Results:

• The Ir-Ni(OH)₂/NF electrode exhibited low overpotentials of 23 mV for HER and 217 mV for OER at 10 mA cm^-2.
• The incorporation of Ir atoms modulated the electronic properties of Ni(OH)₂, creating oxygen vacancies and optimizing active sites.
• An AEMWE electrolyzer using Ir-Ni(OH)₂/NF achieved an ultrasmall cell voltage of 1.54 V at 500 mA cm^-2 with over 225 hours of stability.

Conclusions:

• The Ir-Ni(OH)₂/NF electrode demonstrates excellent bifunctional activity and robust stability for water electrolysis.
• The study provides a promising pathway for designing advanced bifunctional electrocatalysts through single-atom modulation.
• This work contributes to the advancement of efficient and durable water splitting technologies.