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Mn-Induced Support Stabilization and Ir Electronic Activation Enable Acid-Stable, Low-Loading IrO2 Water Oxidation
Zhe Liu1,2,3, Guoxin Ma1, Shixiang Yu4
1State Key Laboratory of Fluorine & Nitrogen Chemicals, School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, P.R. China.
Summary
Manganese doping enhances low-iridium catalysts for acidic oxygen evolution reactions (OER) by improving activity and stability. This study reveals Mn stabilizes iridium nanoparticles and optimizes electron transfer, offering a new design principle for efficient catalysts.
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Low-iridium catalysts face challenges in activity and stability for acidic oxygen evolution reactions (OER).
- The mechanism by which manganese (Mn) doping improves these catalysts is not fully understood.
Purpose of the Study:
- To elucidate the mechanistic role of Mn doping in enhancing the performance of low-loading IrO2/Co3O4 catalysts for acidic OER.
- To investigate how Mn incorporation affects catalyst activity, stability, and the underlying electronic structure.
Main Methods:
- Incorporation of Mn3+ into the octahedral sites of Co3O4 support.
- In situ spectroscopic analyses to probe catalyst behavior during operation.
- Theoretical calculations to understand electronic interactions and structural stabilization.
Main Results:
- Mn doping reduced overpotential by 51 mV and increased operational stability six-fold at 10 mA cm-2.
- Mn3+ incorporation induced strong Mn─O covalency, reinforcing the spinel lattice and stabilizing IrO2 nanoparticles.
- Mn doping suppressed ion leaching and activated Ir sites through interfacial electron transfer, optimizing intermediate adsorption for the oxide-path mechanism (OPM).
Conclusions:
- Mn doping offers a dual-regulation strategy for support chemistry, enhancing both activity and stability of low-loading IrO2 catalysts.
- The findings provide a general principle for designing advanced catalysts for acidic OER.
- Targeted Mn incorporation effectively overcomes limitations in low-iridium catalyst applications.
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