Date

Monday 23 Feb 2026

Time

15:15 - 15:45

Location

BW019

Supervisor

Rik Mom

2nd reviewer

Marc Koper

Jury

Jörg Meyer

The hydrogen evolution reaction (HER) is a key process in water electrolysis and is central to the production of green hydrogen. For this reaction, platinum (Pt) is the state-of-the-art catalyst because of its near-optimal binding energy. Even Pt, however, suffers from the sluggish HER kinetics in alkaline media, which remain a key limitation for efficient water electrolysis under these conditions. Ion–electrode interactions offer an intriguing handle for tuning the catalytic performance, as increasing evidence shows that they have a pronounced effect on HER activity. However, these interactions are challenging to probe experimentally as they occur within the first nanometres of the electrochemical double layer.

In this project, an electrochemical quartz crystal microbalance (EQCM) with mesoporous platinum (mp-Pt) was employed to investigate whether this method can capture cation-electrode interactions in alkaline media. With this configuration, the mp-Pt electrode confines the electric double layer inside its porous structure, so that the EQCM frequency shifts directly reflect mass changes within the double layer.

Measurements in 100 mM LiOH, NaOH, KOH, and CsOH demonstrate that this approach can indeed disentangle cation-specific effects in situ. Moreover, a clear and unexpected trend is observed: when scanning to more positive potentials, positively charged alkali cations are  attracted to the electrode surface. The effect is most clearly resolved for Cs+, whose interfacial mass changes give the strongest measurable signal.

These findings establish EQCM with mp-Pt as a powerful method to reveal how alkali metal cations restructure the electrochemical interface in alkaline media, opening new perspectives for understanding and ultimately improving HER catalysis.