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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Focus Session: Novel Approaches to Surface Plasmon Generated Charges and Heat for Photocatalysis I (joint session O/CPP)

CPP 32.8: Talk

Wednesday, March 20, 2024, 17:15–17:30, MA 141

Catalytic Electron Transfer Inhibited by Coulomb Blockade in Au Nanoparticles — •Monalisa Garai and Thomas Klar — Institute of Applied Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz

Colloidal noble metal nanoparticles (NPs) are excellent catalysts for various chemical redox reactions. They offer alternative reaction pathways and thereby significantly reduce the activation energy for chemical transformations. There are several strategies to reduce the activation energy for kinetically sluggish catalytic reactions, e.g. by changing the size, shape and composition of the NPs and also by changing the specific reaction conditions. To investigate the reaction mechanism of Au NPs of different sizes below 10 nm, we used the 1-electron transfer from ferricyanide (Fe3+) to ferrocyanide (Fe2+) as a model reaction system. We compared the reaction rate of the conversion from Fe3+ to Fe2+ in the presence and absence of the reducing agent triethanolamine (TEOA). It has been shown that the reaction pathway is significantly altered with and without TEOA. TEOA generally transfers electrons to Au NP and causes a negative charging on the Au NP surface. However, if the size of the NPs is very small, especially below 5 nm, the negative charging of the Au NPs is inhibited by the Coulomb blockade effect. As a result, the subsequent catalytic electron transfer from Au NP to Fe3+ is also inhibited, which decreases the overall Fe3+ reduction rate. These experimental results and theoretical calculations will help to develop novel metal NPs for various catalytic processes for environmental remediation.

Keywords: Surface Plasmon Resonance; Gold nanoparticles; catalysis; Coulomb Blockade