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Economic Manganese-Oxide-Based Anodes for Efficient Water Oxidation: Rapid Synthesis and In Situ Transmission Electron Microscopy Monitoring


Heidari, Sima; Balaghi, S Esmael; Sologubenko, Alla S; Patzke, Greta R (2021). Economic Manganese-Oxide-Based Anodes for Efficient Water Oxidation: Rapid Synthesis and In Situ Transmission Electron Microscopy Monitoring. ACS Catalysis, 11(5):2511-2523.

Abstract

Earth-abundant, environmentally friendly, and low-cost manganese oxide materials are promising resources for water oxidation catalysts in clean solar fuel applications. We here introduce a convenient and economic method for manufacturing stable and highly efficient manganese-oxide-based anodes for electrochemical water oxidation under neutral conditions. The electrodes were fabricated through thermal decomposition of acidic KMnO4 solution. The phase transitions of the manganese oxide film during calcination and thermal decomposition of KMnO4 were monitored with in situ heating transmission electron microscopy (TEM), in situ heating scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM/EDX), and in situ heating powder X-ray diffraction (PXRD). In-depth monitoring of formation pathways and phase transformations by in situ techniques under high temperatures shed light upon the fabrication of efficient manganese oxides for energy conversion applications. After parameter optimizations, the best-performing manganese oxide catalyst was applied for water electrolysis for 100 h with a stable current density of 1.0 mA/cm2 at an overpotential of 490 mV in neutral pH. Post operando characterizations of key oxide film properties showed no significant changes. The readily commercially available precursor enables a simple and rapid fabrication method, and the promising stability and high performance of the herein developed electrodes render them quite promising for technological water splitting systems.

Abstract

Earth-abundant, environmentally friendly, and low-cost manganese oxide materials are promising resources for water oxidation catalysts in clean solar fuel applications. We here introduce a convenient and economic method for manufacturing stable and highly efficient manganese-oxide-based anodes for electrochemical water oxidation under neutral conditions. The electrodes were fabricated through thermal decomposition of acidic KMnO4 solution. The phase transitions of the manganese oxide film during calcination and thermal decomposition of KMnO4 were monitored with in situ heating transmission electron microscopy (TEM), in situ heating scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM/EDX), and in situ heating powder X-ray diffraction (PXRD). In-depth monitoring of formation pathways and phase transformations by in situ techniques under high temperatures shed light upon the fabrication of efficient manganese oxides for energy conversion applications. After parameter optimizations, the best-performing manganese oxide catalyst was applied for water electrolysis for 100 h with a stable current density of 1.0 mA/cm2 at an overpotential of 490 mV in neutral pH. Post operando characterizations of key oxide film properties showed no significant changes. The readily commercially available precursor enables a simple and rapid fabrication method, and the promising stability and high performance of the herein developed electrodes render them quite promising for technological water splitting systems.

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Additional indexing

Item Type:Journal Article, not_refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
08 Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > Catalysis
Physical Sciences > General Chemistry
Uncontrolled Keywords:Catalysis, General Chemistry
Language:English
Date:5 March 2021
Deposited On:08 Feb 2022 15:20
Last Modified:28 Jan 2024 02:43
Publisher:American Chemical Society (ACS)
ISSN:2155-5435
OA Status:Green
Publisher DOI:https://doi.org/10.1021/acscatal.0c03388
Project Information:
  • : FunderSNSF
  • : Grant IDCRSII2_160801
  • : Project TitlePhotocatalytic Processes at Solvated Interfaces
  • : FunderUZH Forschungskredit
  • : Grant IDFK-18-106
  • : Project Title
  • Content: Accepted Version