Advanced characterisation of materials for photoelectrochemical energy conversion

The sunlight is capable of answering the global energy need. Semiconducting materials have been developed to convert solar radiation into fuels for energy storage and mobile applications. Electronic band alignment, carrier transport, and reaction kinetics at interfaces make the system optimization a joint adventure for physicists, materials scientists, and chemists. In our group, we apply structural and electrochemical characterization to study nanostructured materials and their stability.

We apply state-of-the-art electron microscopy and spectroscopy to study the surfaces for electrochemical reactions as well as critical interfaces for the charge carrier transport. The insights into the atomic structure are instrumental in understanding the activity of materials. We have validated concepts such as nanostructures, localized doping, and strain engineering to improve the catalytic activity [1].

Stability of photocatalysts is as important as their activity. Oxidation and reduction of oxides can happen at respective anodic and cathodic potentials, especially under sunlight that populates minority carriers. We have developed an illuminated scanning flow cell (iSFC) setup (Fig. 1) to simultaneously study the activity and degradation of photocatalysts under various photoelectrochemical conditions [2]. Thanks to the inline inductive coupled plasma mass spectrometry measurements, the corrosion products can be monitored in operando. We have explored different degradation mechanisms in BiVO4 depending on the light intensity, electrochemical potential as well as the electrolytes [3]. We are expanding the setup to understand the stability of more materials and photoelectrochemical reactions.