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Loading IrOx Clusters on MnO2 Boosts Acidic Water Oxidation via Metal-Support Interaction
Yunchu Zeng1, Li Yan1, Shubo Tian1
1State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
ACS Applied Materials & Interfaces
|September 29, 2023
Summary
This study developed highly efficient iridium oxide (IrO2) nanoclusters on manganese dioxide (MnO2) nanosheets for acidic water oxidation, a key step in green hydrogen production. The IrO2/ε-MnO2 catalyst demonstrated superior performance and stability compared to other phases.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
- Green Energy
Background:
- Noble metal electrocatalysts are essential for efficient acidic water oxidation, crucial for green hydrogen energy production.
- Traditional catalysts suffer from limited intrinsic activity and poor atom efficiency due to large noble metal particle sizes on inactive supports.
- Developing highly active and stable electrocatalysts is critical for advancing hydrogen energy technologies.
Purpose of the Study:
- To synthesize and evaluate iridium oxide (IrO2) nanoclusters supported on different phases of redox-active manganese dioxide (MnO2) nanosubstrates.
- To investigate the effect of MnO2 phases (α, δ, and ε) on the electrocatalytic activity and stability of IrO2 nanoclusters for acidic water oxidation.
- To elucidate the structure-activity relationships and understand the role of metal-support interactions in enhancing catalytic performance.
Main Methods:
- Synthesis of IrO2 nanoclusters (< 2 nm) supported on α-MnO2, δ-MnO2, and ε-MnO2 nanosubstrates.
- Electrochemical measurements, including overpotential determination at 10 mA cm-2 in 0.5 M H2SO4 and long-term stability tests.
- X-ray Photoelectron Spectroscopy (XPS), Bader charge analysis, and Density Functional Theory (DFT) calculations to probe electronic structure and metal-support interactions.
Main Results:
- IrO2/ε-MnO2 exhibited excellent oxygen evolution reaction (OER) performance with a low overpotential of 225 mV at 10 mA cm-2, outperforming IrO2/α-MnO2 (242 mV) and IrO2/δ-MnO2 (286 mV).
- The IrO2/ε-MnO2 catalyst demonstrated robust stability, maintaining its operating potential during 50 hours of continuous operation at 10 mA cm-2.
- Strong metal-support interactions in IrO2/ε-MnO2 were found to regulate the electronic structure of Ir sites and stabilize nanoclusters, enhancing activity and durability.
Conclusions:
- The ε-MnO2 phase provides an optimal redox-active nanosubstrate for supporting IrO2 nanoclusters, leading to significantly enhanced acidic OER performance.
- The enhanced catalytic activity and stability are attributed to strong metal-support interactions that optimize the electronic properties of Ir and improve nanocluster anchoring.
- This work highlights the potential of rationally designed noble metal nanoclusters on redox-active supports for efficient and stable green hydrogen production.
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