Dynamic Structure Evolution of Composition Segregated Iridium-Nickel Rhombic Dodecahedra toward Efficient Oxygen...

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• The oxygen evolution reaction (OER) is crucial for energy conversion devices.
• Limited understanding of dynamic catalyst evolution under OER conditions hinders optimization.
• Structure-activity relationships in OER catalysts require further investigation.

Purpose of the Study:

• To investigate the dynamic structural evolution of IrNi nanoparticles (NPs) during OER.
• To correlate catalyst self-reconstruction with OER performance in different electrolytes.
• To provide insights for designing efficient OER catalysts with controlled composition.

Main Methods:

• Synthesis of monodispersed IrNi nanoparticles with distinct composition-segregated features.
• In-situ/operando characterization of catalyst structural evolution under various OER conditions (acidic and alkaline).
• Correlation of structural changes with OER activity measurements.

Main Results:

• Observed self-reconstruction of IrNi NPs during OER.
• Formation of an Ir-skin framework in acidic electrolyte and a Ni-rich surface layer in alkaline electrolyte due to Ni migration.
• Significant OER performance enhancements achieved in both acidic and alkaline conditions following self-reconstruction.

Conclusions:

• The self-reconstruction mechanism of IrNi NPs is critical for enhanced OER activity.
• Electrolyte-dependent surface reconstruction (Ir-skin vs. Ni-rich) dictates catalytic behavior.
• This study offers a pathway for designing advanced OER catalysts by controlling compositional distribution and dynamic evolution.