Stability and activity of manganese oxide electrocatalysts stabilized by organic ligands for water oxidation

• Grant number: 21/00908-9
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: March 01, 2021
• End date: February 28, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Fabio Henrique Barros de Lima
• Grantee: Cássio Luis Pires Lucato
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 19/22183-6 - Electrocatalysis VI: fundamental and applied aspects of emerging and classical problems in electrochemical energy conversion, AP.TEM
• Associated scholarship(s): 24/08046-4 - Manganese-based Oxides as Stable Water and Methanol Electrochemical Oxidation Catalysts for Hydrogen Production, BE.EP.DD

Abstract

The energy demand boost in conjunction with population growth increased substantially anthropic interference in the carbon biogeochemistry cycle, resulting in a climate change scenario and unleashing risks bound to it. Therefore, research upon sustainable energysources or fossil divergent has drawn attention, standing out H2, which can be producedby proton reduction stemming from the water electro-oxidation reaction. The best performances in water electrocatalysis are achieved by noble and scarce-based metal oxide materials, such as IrO2and RuO2. Photosynthetic organisms have manganese oxide clusters (ce Mn4CaO5) with a coordination sphere composed mainly of amino acid residues withcarboxylic groups as a side chain. In turn, such groups act both as inductors of proton trans-fer coupled to electrons (CPET) and as stabilizers of Mn of high oxidation number. Still, such composites are key to the water oxidation reaction with a 160 mV overpotential at physiological pH. Those aspects awake research in mimetic electrocatalysts research; in other words, manganese-based with coordination sphere with molecules resembling natural environment. Having this biomimetic concept as inspiration, this research project puts forward the synthesis, characterization, and the scrutiny of electrocatalytic activity manganese oxide combined with organic molecules, building up diverse structures, such as (1) manganese oxide nanoparticles surface-modified with molecules having carboxylic groups (ex: benzo-ate); (2) manganese-based Metal-Organic Frameworks (MOF) with organic ligands (ex: teref-talate). The goal is to elucidate ligand molecules' influence in both manganese oxide activityand stability during water electrooxidation, mainly in neutral and acid electrolytes. Electrocatalysts will be synthesized through literature-based ways and characterized by diverse techniques - including spectroscopic, spectrometric, and electronic microscopy. Electrochemistry measures and faradaic efficiency for O2 evolution will be calculated by online Differential Electrochemical Mass Spectroscopy (DEMS) and in-line Gas Chromatography (GC) inelectrochemistry cells. (AU)