Two-dimensional IrN₂ monolayer: An efficient bifunctional electrocatalyst for oxygen reduction and oxygen evolution...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Bifunctional electrocatalysts are essential for efficient renewable energy conversion and storage systems.
• Developing stable and highly active electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a significant challenge.

Purpose of the Study:

• To propose and investigate novel two-dimensional (2D) transition dinitride (TMN2) monolayers as potential bifunctional electrocatalysts for ORR and OER.
• To identify specific TMN2 materials with superior catalytic performance and stability.

Main Methods:

• Utilized swarm-intelligence structure search combined with density functional theory (DFT) computations.
• Analyzed the structural, electronic, and stability properties of various TMN2 monolayers.
• Investigated the catalytic activity for ORR/OER by examining d-band centers of active sites.

Main Results:

• Identified several TMN2 monolayers (V, Co, Rh, Pd, W, Re, Ir) exhibiting excellent thermal, dynamic, and chemical stability with inherent metallic properties.
• The iridium nitride (IrN2) monolayer demonstrated exceptional bifunctional activity for ORR and OER, with low overpotentials of 0.47 V and 0.27 V, respectively.
• Rationalized the high catalytic activity of IrN2 based on the electronic structure (d-band centers) of its active sites.

Conclusions:

• 2D TMN2 monolayers, particularly IrN2, represent a promising new class of highly efficient and stable bifunctional electrocatalysts for oxygen reactions.
• These findings expand the library of 2D nanomaterials with hypercoordinate structures and offer a new avenue for designing advanced electrocatalysts for energy applications.