Single molecule potentiometry
Background
Electrochemical hydrogen catalysis on electrodes belong to the most important reactions underpinning the sustainable conversion of electricity and chemical energy carriers. The macroscopic kinetics of the constituting hydrogen oxidation (HOR) and hydrogen evolution reactions (HER) are well understood. Single molecule potentiometry allows us to understand the intrinsic kinetics of elementary steps involved in HOR / HER without ensemble averaging effects that are intrinsic limitations of macroscopic kinetic studies.
Project Description
In this project, we will probe the potential response when single H2 molecules react on electrode surfaces and thereby gain microscopic kinetic insights about the HOR / HER process.
In this project you will do the following:
• Electrode tip fabrication: You will fabricate Pt electrode tips with minimal exposed electrochemical surface area (at most 0.01 μm2) with the help of PD Dr. rer. nat. Friedrich Esch’s Lab.
• Electrochemical surface area determination: You will test the electrochemical surface area of the prepared tips in Prof. Dr. Max Hülsey’s Lab. This will be done ideally on electrode tips with ECSA less than 0.001 μm2 for your single molecule potentiometry experiments. The small ECSA will allow us enough measurement sensitivity to resolve current signals associated with elementary steps during single molecule HOR.
• Single molecule potentiometry: We will use the prepared electrode tips and high precision potential measurements for probing the open circuit potential response of HOR / HER by varying the H2 partial pressure introduced into the electrochemical cell.
Expected Outcome
By the end of the project, we hope to develop a standardized procedure for fabricating and testing electrode tips that allow us to resolve single molecule interactions of small molecules on the electrode surface. Furthermore, we hope to gain insights into the elementary reaction events involved in HOR / HER for deeper mechanistic understanding. In the future, we hope to extend our methodology to probe other important small molecule oxidation/reduction reactions.
