Hiwi Position for pH mapping with STM

02.07.2026, Academic staff

Internship/Hiwi position (10–20 h/week, until the end of 2026) on depositing Pt onto STM tips to map local pH at electrode surfaces with nanoscale resolution. Interfacial pH often differs from bulk, skewing kinetic/thermodynamic analysis (e.g., HER, CO₂RR). Pt-decorated tips read local pH via RHE open-circuit potential and the Nernst equation; your focus: how deposition conditions shape Pt morphology, which sets spatial resolution. Lab experience required; contact [email protected].

The internship deals with depositing platinum onto an STM tip to map pH values on electrode surfaces and within the boundary layer using modified STM tips. The pH is an important parameter in electrochemical reactions since it impacts the reaction environment and oxonium/hydroxide-ions are often involved in electrochemical reactions. Often times it is assumed that the pH of the bulk solution is the same as the interface, however this has been shown to be false, especially in unbuffered systems. This causes wrong estimation of appropriate kinetic and thermodynamic parameters related to pH effects. Exemplary reactions are affected by pH gradient effects are the hydrogen evolution reaction and the electrochemical reduction of CO2.

However not just within the electrochemical cell pH gradients are present during operation, but also across the surface of the electrodes depending on roughness, crystal facet, lattice errors and so on. These features are only resolvable at the nanoscale, but current methodology is lacking in resolution and has other issues that make resolving these effects under realistic conditions very challenging.

We want to improve upon previous SEC(C)M measurements by using platinum decorated tips to make resolving these nanoscale features possible. Higher spatial resolution will provide a more refined view on structure-effect relations pertaining to pH environments on surfaces. The local pH can be determined especially easily using electrochemical techniques such as the measurement of the open cell potential of a reversible hydrogen electrode via the Nernst equation. Since platinum is an excellent hydrogen splitting catalyst and therefore makes reading the local pH possible via the Nernst equation, it is the ideal material to decorate the STM tip. Following up on previous work, you will determine how Pt deposition techniques and conditions affect the morphology of the deposited Pt.

Understanding and optimizing the morphology of Pt on the STM tip is critical since it will determine the resolution of the measurement as it defines the minimum volume element that the tip interacts with to measure the pH.

What do you bring?

• Interest in electrochemistry and surface science
• Motivation to learn new things
• Ability to think critically about data
• Experience working in a chemistry lab
  
  

What do we offer?

• Hiwi position until the end of this year for 10-20 hours per week
• Small and young group
• Opportunity to work on fundamental problems in electrochemistry
• Automated data analysis using Python (optional)
  
  

Are you interested? Please, contact [email protected] with your CV for further information.

The position is suitable for disabled persons. Disabled applicants will be given preference in case of generally equivalent suitability, aptitude and professional performance.

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Kontakt: [email protected]