Operando Analysis of Water Splitting Photoelectrodes at High Current Densities
David Tilley a
a Department of Chemistry, University of Zurich, Zürich, Switzerland
Proceedings of International Conference on Frontiers in Electrocatalytic Transformations (INTERECT22)
València, Spain, 2022 November 21st - 22nd
Organizers: Sara Barja, Nongnuch Artrith and Matthew Mayer
Invited Speaker, David Tilley, presentation 014
DOI: https://doi.org/10.29363/nanoge.interect.2022.014
Publication date: 11th October 2022

Photoelectrochemical (PEC) water splitting combines light absorption and electrocatalysis into the same device or material. In so-called "emerging" materials systems, which are less well characterized and understood, it is often unclear where the problem lies when the performance begins to decay with time. The light absorber material itself could be changing, resulting in a decaying photovoltage output, or the surface catalyst may be changing in some may, reducing its efficacy. We have developed a novel implementation of the dual working electrode (DWE) technique that can deconvolute the photovoltaic performance from the surface catalytic performance under normal water splitting conditions (i.e., operando), in order to identify the problematic part of the device. I will then discuss our work towards developing a suitable model for electrochemical impedance spectroscopy (EIS) of multilayered photocathode materials, where the processes taking place in each layer can be characterized and the problematic interfaces can be identified, enabling optimization. Examples of interface treatments that improve the performance of thin film-based water splitting photoelectrodes, such as the deposition of molecular dipole layers, will also be discussed.

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