Overview
The electrochemical oxygen evolution reaction (OER) is considered one of the key catalytical processes towards a renewable energy economy. Due to OER being the limiting factor in electro- and photocatalytic water splitting it is one of the core topics of catalytical research over the last decade. Metal oxides have been identified as highly effective and stable OER catalyst materials. Despite extensive research on the topic, structure and chemical composition of these oxides under reaction conditions is still unclear. To obtain a better understanding of these properties, scientists recently revisited the oxidation behavior of different metals during electrocatalytic processes [1,2]. These studies identified solution pH as the key driving factor for the formation of different oxide species, with different activities towards OER (Fig.1 A) [3]. Up to now, the effects of the anions in theses acidic solutions and their interaction with the metal surface on the oxide formation are not investigated. The research group for Physics of Complex fluids demonstrated on a different topic that these effects should not be overlooked, as they promote different oxide compositions and surface structures [4] (Fig.1 B).
Examples of recent work where fluids of different compositions were used to influence the nanoscopic structure and composition of the solid phase. A: The formation of different oxide species on gold electrodes shown via electrochemistry. B: The nanoscopic restructuring of solid surfaces in dependence of the used anion.
Research Objectives
In this work we will investigate how different anions influence the oxide formation on polycrystalline gold electrodes. To this end we will employ electrochemical methodology such as cyclic voltammetry and electrochemical impedance spectroscopy to both identify the interaction of different anions with the gold surface as well as the redox potential for gold-oxide formation and the OER onset potential. To furthermore strengthen our understanding of the type and strength of these anion-gold interactions in dependence of bias we will employ our newly established electrochemical quartz microbalance to estimate the extend of ion adsorption. We intend to use anions known to strongly adsorb to gold such as phosphoric acid and sulfuric acid, as well as weakly interacting anions such as nitric acid and tetrafluoro boric acid at constant pH and record the change in oxide composition and structure. To this end, techniques established in the group for physics in complex fluids, such as in situ atomic force microscopy and Raman microscopy as well as ex-situ electron microscopy and X-ray photoelectron spectroscopy can be employed. Once different oxide structures are identified we employ OER studies to link structural change to catalytic activity.
Learning Objectives
In addition to the standard learning objectives for a Master’s project (research planning, academic writing, data presenting, how to work in a lab environment, etc.), you will learn how to:
· prepare electrochemical experiments and solutions
· perform electrochemical experiments and quartz micro balance experiments
· evaluate and interpret electrochemical and gravimetric data
· work with state-of-the art microscopic and/or spectroscopic methods
Contact Information
· Daily Supervision: Dr. Maximilian Jaugstetter
· Supervision: Prof. Dr. Frieder Mugele
[1] Nong, H.N., Falling, L.J., Bergmann, A. et al. Key role of chemistry versus bias in electrocatalytic oxygen evolution. Nature 587, 408–413 (2020). https://doi.org/10.1038/s41586-020-2908-2
[2] Rik Mom, Lorenz Frevel, Juan-Jesús Velasco-Vélez, Milivoj Plodinec, Axel Knop-Gericke, and Robert Schlögl, Journal of the American Chemical Society 2019 141 (16), 6537-6544, DOI: 10.1021/jacs.8b12284
[3] Shengxiang Yang and Dennis G. H. Hetterscheid, ACS Catalysis 2020 10 (21), 12582-12589
DOI: 10.1021/acscatal.0c03548
[4] VE Alagia, S Mohanakumar, MHG Duits, F Mugele, Geochimica et Cosmochimica Acta, 2025, https://doi.org/10.1016/j.gca.2025.06.012