On 12 May 2026 Bart van den Boorn will defend his thesis called "A Microkinetic Modeling Framework for Oxygen Evolution at Semiconductor Electrodes''.
- Promotor: dr. ir. Matthijs van Berkel
- Co-promotor: dr. Anja Bieberle-Hütter
Summary
Photoelectrochemical (PEC) water splitting offers a way to produce green hydrogen directly from sunlight and water. It could therefore become a key technology in the production of sustainable fuels and in the chemical industry. However, PEC cells are not efficient enough for large-scale use. A major challenge is identifying suitable semiconductor materials that efficiently absorb sunlight and have suitable properties for water splitting. This material challenge is further complicated because the mechanism of the reaction that generates oxygen, theoxygen evolution reaction (OER),remains poorly understood. This is in part because parameters that are key to the understanding of this mechanism cannot easily be measured experimentally.
The key contribution of this dissertation to tackling these challenges is the development of a computational model that couples semiconductor physics and electrochemical reactions. Specifically, it links the transport of light-generated charge carriers inside the semiconductor with the OER reaction taking place at the semiconductor surface. By coupling these processes, the model reveals how factors such as light intensity, trap states, and electric fields affect the performance of the OER reaction. These are effects that cannot be captured by models using simplified descriptions of semiconductor physics.
A further major contribution in this dissertation is the development of tools, such as parameter estimation and sensitivity analysis, that use the model to give insight into the key parameters of the semiconductor material and the OER mechanism. In this way, the model is used to estimate parameters such as reaction rates directly from experimental data, even when these parameters cannot be measured independently. Additionally, sensitivity analysis is used to identify which parameters most strongly affect OER performance. In particular, the reorganization energy is found to have a significant impact and is shown to specifically affect the rate-determining step of the OER.
Overall, the modeling framework developed in this dissertation connects detailed physical modeling with experiments. This leads to improved understanding of the OER mechanism and provides practical tools for fast and reliable evaluation of prospective semiconductor materials, thereby contributing to the advancement of photoelectrochemical water splitting and efficient solar hydrogen production.
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