Boron-Induced Interstitial Effects Drive Water Oxidation on Ordered Ir-B Compounds

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Interstitial filling of light atoms significantly alters catalyst electronic structure and adsorption properties.
• Ordered intermetallic structures offer superior stability and activity compared to conventional doping or surface modification.
• Achieving ordered interstitial filling in dense metal lattices like iridium (Ir) is challenging.

Purpose of the Study:

• To develop a novel strategy for creating ordered intermetallic Ir-B compounds.
• To investigate the interstitial effects of boron (B) atoms in the Ir lattice.
• To evaluate the catalytic performance and stability of the synthesized IrB1.1 for oxygen evolution reaction (OER).

Main Methods:

• A high-temperature molten salt assisted synthesis strategy was employed.
• The formation of intermetallic Ir-B compounds (IrB1.1) with ordered B filling was confirmed.
• Electrochemical performance for OER was assessed and compared to commercial IrO2.

Main Results:

• Ordered interstitial B atoms in IrB1.1 created favorable adsorption surfaces via a donor-acceptor architecture.
• The IrB1.1 catalyst exhibited an optimal free energy uphill in the rate-determining step of OER, enhancing activity.
• Strong Ir-B coupling suppressed Ir demetallation and reconstruction, ensuring high catalytic stability.
• IrB1.1 demonstrated superior OER performance compared to commercial IrO2 and was validated in proton exchange membrane water electrolyzers (PEMWEs).

Conclusions:

• The molten salt strategy successfully produced IrB1.1 with ordered interstitial B atoms.
• Boron-induced interstitial effects significantly boost OER activity and stability in Ir-based catalysts.
• IrB1.1 represents a promising catalyst for efficient water electrolysis applications.