Plasmon effects during oxygen evolution reaction at Co oxide layers

• Grant number: 24/15486-0
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• Start date: November 25, 2024
• End date: February 24, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Susana Inés Córdoba de Torresi
• Grantee: Susana Inés Córdoba de Torresi
• Visiting researcher: Philippe Allongue
• Visiting researcher institution: Centre National De La Recherche Scientifique/Cnrs, France
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/00675-4 - Tying up materials for electrochemical energy storage and catalysis, AP.TEM

Abstract

The production of low-emission hydrogen is central to the current energy transition. A promising alternative involves water splitting via renewable energy sources such as solar and wind, resulting in what is called green hydrogen. Water electrolysis, which includes the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, faces significant challenges. The OER, in particular, suffers from substantial kinetic limitations. Transition metal oxides, abundant on Earth, present a viable solution as electrocatalysts for large-scale electrolyzers. Extensive research has been conducted to design more efficient and stable OER catalysts, exploring strategies such as alloying and defect engineering. Additionally, decorating OER electrocatalysts with plasmonic metallic nanoparticles (NPs) appears as a complementary strategy to improve the activity of established materials. Illumination excites localized plasmons in these NPs, thereby enhancing both OER and HER activities. The mechanisms behind plasmon-induced electrochemistry are intricate. The interaction of plasmonic NPs with light may result in an amplified electromagnetic field, charge carrier separation, and thermal effects. These mechanisms collectively contribute to the enhanced performance observed in plasmonic electrochemical systems. Ideally, the system is optimized to favor charge separation (formation of hot electrons and hot holes) that can boost the electrochemical reaction driven by an applied potential. For NPs deposited on a semiconductor, a critical question remains: how do hot electron-hole pairs generated by irradiation influence the rate of electrochemical reactions? Specifically, can hot carriers drive these reactions in a non-thermal manner, or does heat dissipation ultimately activate the reaction rate through temperature increase (Arrhenius dependence)? Further research is essential to fully understand these mechanisms and optimize them for enhanced energy conversion. We primarily aim to investigate the mechanisms of plasmon-induced electrocatalysis, specifically the oxygen evolution reaction (OER) at CoOx layers decorated with gold NPs. This layer will be produced by the electrodeposition of Co ions on an Au buffer layer, which will subsequently be anodized to generate the oxide layer. The plasmonic effects will be exploited to conduct operando Raman characterizations, which will yield insights into the electrocatalyst structure during OER. (AU)