Atom-Efficient Ir Nanoclusters in Laser-Engineered MoC@N-Carbon for Ultralow-Overpotential Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts is crucial for energy conversion technologies.
• Molybdenum carbide (MoC) and nitrogen-doped carbon (NC) are promising materials, but their catalytic activity needs enhancement.
• Iridium nanoclusters (IrNC) can improve catalytic properties through synergistic effects.

Purpose of the Study:

• To synthesize and characterize a novel bifunctional electrocatalyst composed of iridium nanoclusters incorporated into a MoC/N-doped carbon matrix (IrNC/MoC@NC).
• To evaluate the electrocatalytic performance of IrNC/MoC@NC for the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) in alkaline media.
• To elucidate the structure-activity relationship and understand the origin of the enhanced catalytic activity.

Main Methods:

• Synthesis of IrNC/MoC@NC via self-polymerization and pulsed laser irradiation in liquids (PLIL).
• Electrochemical characterization including overpotential measurements for HER and HzOR.
• In situ Raman spectroscopy and theoretical calculations to study interfacial electronic properties.
• Fabrication of a hydrazine-splitting electrolyzer using the synthesized catalyst.

Main Results:

• The PLIL process effectively enhanced MoC crystallinity and pyridinic-N defects, enabling interfacial defect engineering.
• IrNC/MoC@NC demonstrated outstanding bifunctional electrocatalytic activity, with ultralow overpotentials for HER (25 mV at 10 mA cm⁻²) and high mass activity for HzOR (133.6 A g⁻¹).
• Interfacial electronic polarization and dynamic charge redistribution at the Mo-Ir-N interface were identified as key factors for enhanced performance, rather than covalent bonding.

Conclusions:

• The IrNC/MoC@NC catalyst exhibits superior bifunctional electrocatalytic performance in alkaline media.
• The enhanced activity is attributed to interfacial electronic polarization and defect engineering at the Mo-Ir-N interface.
• A symmetric electrolyzer based on IrNC/MoC@NC achieved efficient hydrazine splitting with excellent durability, highlighting its potential for energy applications.