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Stabilizing Lattice Oxygen to Enable Durable MnO2 Electrocatalyst for Simultaneous Acidic Hydrogen Production and
Yingjie Song1,2, Jialong Qian1, Shengnan Li2
1State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, 100029, Beijing, China.
Angewandte Chemie (International Ed. in English)
|February 22, 2025
Summary
Manganese oxide electrocatalysts for water electrolysis are stabilized by replacing oxygen evolution with glucose oxidation. This strategy enhances durability 1100-fold, enabling efficient production of formic acid and hydrogen.
Area of Science:
- Electrochemistry and Materials Science
- Catalysis for Energy Conversion
Background:
- Proton exchange membrane (PEM) water electrolyzers require stable, earth-abundant electrocatalysts for acidic conditions.
- Manganese oxide (MnO2) is a promising electrocatalyst for oxygen evolution reaction (OER) but suffers from overoxidation, with mechanisms not fully understood.
- Lattice oxygen involvement in γ-MnO2 OER via Mars-van-Krevelen mechanism contributes to Mn dissolution and electrode instability.
Purpose of the Study:
- To elucidate the mechanism of γ-MnO2 instability during OER in acidic media.
- To develop a strategy for stabilizing γ-MnO2 and enhancing its durability.
- To demonstrate a sustainable route for producing valuable chemicals and fuels using stabilized MnO2.
Main Methods:
- Experimental investigation of γ-MnO2 electrocatalyst stability during OER.
- Theoretical calculations to understand the role of lattice oxygen and Mn dissolution.
- Electrochemical testing of γ-MnO2 for glucose oxidation to formic acid, following a Langmuir-Hinshelwood mechanism.
Main Results:
- Lattice oxygen release during OER was identified as a key factor in Mn dissolution and electrode degradation.
- Replacing OER with glucose oxidation significantly stabilized γ-MnO2, enhancing durability by 1100 times (up to 960 hours).
- Demonstrated high production rates for formic acid (487.1 mmol h⁻¹) and hydrogen (16.7 L h⁻¹) in a PEM electrolyzer.
Conclusions:
- Stabilizing lattice oxygen by shifting from OER to glucose oxidation effectively suppresses Mn overoxidation and improves electrocatalyst durability.
- This approach offers a sustainable and scalable method for converting water and biomass into valuable chemicals and fuels.
- The findings provide critical insights for designing robust electrocatalysts for future energy applications.
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