Coordinatively Unsaturated IrC₃ Single-Atom Catalysts for Efficient Methanol Oxidation Reaction

Area of Science:

• Electrochemistry
• Catalysis
• Renewable Energy

Background:

• Methanol oxidation reaction (MOR) is vital for energy conversion but hindered by slow kinetics, particularly CO oxidation.
• Strong CO adsorption and limited hydroxyl (OH) species at active sites impede MOR efficiency.

Purpose of the Study:

• To develop a single Ir atom catalyst with IrC3 sites for efficient electrocatalysis of MOR at elevated temperatures.
• To address the challenge of CO poisoning and insufficient OH species in MOR.

Main Methods:

• Development of single Ir atom catalysts featuring coordinatively unsaturated IrC3 sites.
• Electrocatalysis of MOR under elevated temperatures using a high-temperature polymer electrolyte membrane electrolyzer (HT-PEME).
• Analysis of methanol and CO adsorption energies and electrochemical water dissociation.

Main Results:

• The IrC3 sites exhibit stronger methanol adsorption and weaker CO adsorption, breaking the scaling relationship.
• Accelerated electrochemical water dissociation by IrC3 and IrC4 sites generates abundant *OH species.
• The catalyst achieved an onset potential of 0.05 V and a high H2 generation rate (8694 molH2 molIr-1 h-1) at 180°C.

Conclusions:

• The developed IrC3 single atom catalyst significantly enhances MOR kinetics by balancing adsorption energies and providing ample *OH species.
• This catalyst demonstrates superior performance compared to conventional Ir-C and Pt/C catalysts in HT-PEME.
• The findings offer a promising strategy for efficient hydrogen utilization via MOR.