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Published on: June 9, 2023
Modulating D-Band Electron Occupancy in Ru-Based Heterostructures for Durable Acidic Oxygen Evolution
Tianwen Liu1, Xiaoxia Chen1, Jin Wang1
1National & Local Joint Engineering Laboratory For New Petro-Chemical Materials and Fine Utilization of Resources, Key Laboratory of Light Energy Conversion Materials of Hunan Province College, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan, China.
A novel RuO2/Mn3O4 heterojunction with oxygen vacancies offers a durable, iridium-free electrocatalyst for the oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE). This advanced catalyst demonstrates high activity and stability, paving the way for efficient green hydrogen production.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Developing iridium-free electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing proton exchange membrane water electrolysis (PEMWE).
- Achieving a balance between high activity and long-term durability in acidic media remains a significant challenge for OER electrocatalysts.
- Iridium-based catalysts are effective but expensive and scarce, necessitating the development of viable alternatives.
Purpose of the Study:
- To design and synthesize a stable, iridium-free electrocatalyst for the oxygen evolution reaction (OER).
- To investigate a RuO2/Mn3O4 heterojunction with engineered oxygen vacancies (Ov) as a potential high-performance alternative to iridium.
- To evaluate the catalytic activity, durability, and reaction mechanism of the engineered heterojunction in acidic conditions relevant to PEMWE.
Main Methods:
- Fabrication of a RuO2/Mn3O4 heterojunction with controlled oxygen vacancies (Ov).
- Electrochemical characterization including overpotential measurements and turnover frequency calculations.
- In situ spectroscopy and density functional theory (DFT) calculations to elucidate the reaction mechanism and electronic structure.
Main Results:
- The engineered RuO2/Mn3O4-Ov catalyst exhibited significantly enhanced OER activity, achieving a low overpotential of 185 mV at 10 mA cm⁻².
- The catalyst demonstrated a turnover frequency 188-fold higher than commercial RuO2 and maintained stable operation for over 200 hours at 100 mA cm⁻² in 0.1 M HClO4.
- DFT calculations and in situ spectroscopy revealed optimized electronic properties, strengthened Ru-O covalency, and a unique dual H2O adsorption configuration facilitating efficient O-O coupling.
Conclusions:
- The RuO2/Mn3O4 heterojunction with engineered oxygen vacancies presents a highly active and durable iridium-free electrocatalyst for the oxygen evolution reaction.
- The catalyst's performance is attributed to favorable electronic structure modifications and an enhanced adsorption configuration for water molecules.
- This development shows significant promise for replacing iridium-based catalysts in demanding applications like proton exchange membrane water electrolysis (PEMWE).
