Transient Absorption Spectroscopy for operando charge carrier measurements during PhotoElectroChemical water splitting

ICPEES is a research institue of the CNRS and University of Strasbourg housing 60 permanents researcher and professors working in the field of catalysis and chemistry. The internship will be conducted between two teams of the institute: the Functionnal Polymer team for the synthesis of organic semiconductor and the Photocatalysis and Photoconverison team for light activated H2 production.

Context

With the global increase in energy consumption, environmental issues are also escalating due to the reliance on fossil fuels. To reduce the use of fossil fuels, hydrogen production could be a solution, serving as an energy vector in many sectors. To shift from the widespreaded method of hydrogen production, still relying on fossil fuel reforming, toward green hydrogen production, photoelectrochemical water splitting emerged as an attractive approach to produce H₂ directly from water and sunlight. For an efficient conversion process, it is essential to employ electrodes composed of materials that simultaneously combine several key properties. These include strong light-harvesting ability to absorb a broad range of the solar spectrum, high charge carrier mobility to ensure the efficient separation and transport of electron–hole pairs (e⁻/h⁺), and effective catalytic activity to promote redox reactions. To combine these properties, the development of composite electrodes that integrate multiple materials is necessary.¹ These composite systems can combine the strengths of individual materials to fulfill the various functions required for efficient photoelectrochemical water splitting. However, due to the inherent complexity of these composite systems, it is often difficult to determine which specific property is limiting the overall performance of the electrode. This lack of clarity can hinder the optimization of photoelectrochemical cells and the development of more efficient materials.

Advanced time-resolved spectroscopy techniques, such as Transient Absorption Spectroscopy (TAS), can provide valuable insights into the dynamics of charge carriers and the mechanisms of photo-induced reactions.² These techniques allow researchers to study the ultrafast processes that occur in photoelectrodes upon light absorption. However, these spectroscopy techniques are typically performed ex situ, meaning that the measurements are conducted outside of the operational environment of the photoelectrochemical cell. This approach may not fully capture the real-time behavior and interactions that occur under actual working conditions.

To address this limitation, this internship between ICPEES and IPCMS proposes an innovative approach: the development of operando Transient Absorption Spectroscopy measurements directly within a photoelectrochemical cell. This methodology will enable real-time monitoring of photo-induced processes, providing a deeper and more accurate understanding of the factors governing the performance of photoelectrodes.

Objectives

The first task will involve the synthesis of photoelectrodes based on TiO₂ and BiVO₄, which are widely recognized for their potential in photoelectrochemical water splitting. The intern will use methods already available at ICPEES to fabricate these photoelectrodes. Following the synthesis, the intern will modify the photoelectrodes through the deposition of cocatalysts (CoO, Pt) or by doping with other elements (W for BiVO₄). These modifications aim to modify the properties of the electrodes, such as their light absorption, charge separation, and catalytic activity.^3,4

The second step will be the adaptation of the photoelectrode properties for compatibility with in situ TAS and photoelectrochemical cell measurements. This task will require a understanding of both the material properties and the technical requirements of the TAS and PEC setups. The intern will need to optimize the electrode design to ensure that they can be effectively studied using these advanced techniques. Once the photoelectrodes are prepared and optimized, the intern will conduct campaigns of operando TAS measurements. After data treatment and analysis, these measurements will provide insights into the behavior of charge carriers, depending of the doping or cocatalyst deposition to shed light on the mechanisms that govern the photoelectrochemical performance.

Application

This internship is intended for a Master 2 student in Physico-Chemistry, or Materials Science. The multidisciplinary project will require skills in materials synthesis and characterization. The student will be trained to carry out photoelectrochemical and spectroscopic measurements. The work will involve materials characterization (UV-Vis spectroscopy, XRD, SEM, XPS), bibliographic research, data analysis, and active participation in team work. The internship will take place at ICPEES and IPCMS, on the Cronenbourg campus (ZRR). Depending on progress and interest, this internship may also open the door to a PhD on similar topics.

For more information and to apply, please send a CV and a motivation letter and and your M1 academic transcript to T. Cottineau,  and M. Rahmani.

References

1             J. H. Kim, D. Hansora, P. Sharma, J.-W. Jang and J. S. Lee, Chem. Soc. Rev., 2019, 48, 1908–1971.

2             M. Forster, D. W. F. Cheung, A. M. Gardner and A. J. Cowan, The Journal of Chemical Physics, 2020, 153, 150901.

3             T. Favet, S. Sharna, V. Keller, M. A. El Khakani and T. Cottineau, Materials Today Energy, 2023, 37, 101376.

4             M. Torras, M.-A. Dourges, J. Quinet, A. Demange, T. Cottineau, J.-P. Delville, M.-H. Delville and T. Toupance, ACS Appl. Energy Mater., 2025, 8, 3929–3941.

This project is for a master 2 student in the field of Chemistry, Physico-Chemistry or Material Science. It requires a strong motivation for experimental work and an ability to understand the multidisciplinary aspects of the project.