Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 65: Solid-Liquid Interfaces: Reactions and Electrochemistry III

O 65.5: Talk

Wednesday, March 19, 2025, 16:00–16:15, H6

Degradation of TiO₂/Pt catalyst interfaces during operation — •Sergej Levashov¹, Tim Rieth^1,2, Ian D. Sharp^1,2, and Johanna Eichhorn¹ — ¹TUM School of Natural Sciences — ²Walter Schottky Institut

Photoelectrochemical (PEC) water splitting is a promising approach for generating green fuels. However, photosystems often degrade in the harsh chemical environment required for PEC water splitting. To overcome this limitation, understanding the starting point of the degradation and the exact degradation mechanism at the nanoscale is required. In this work, we study TiO₂ thin films grown by atomic layer deposition (ALD) combined with Pt catalyst layers, deposited by sputtering and two different ALD processes, by in-situ/operando atomic force microscopy and elucidate their changes in topography and mechanical properties under operation conditions. The main difference between the Pt is the growth mechanics: while sputtering yields a continuous film, the ALD growth results in Pt islands. On the macroscale, the ALD grown Pt catalysts show similar onset potentials and saturation current densities as the sputtered ones. At the nanoscale, we observe that the ALD Pt films are more stable than sputtered Pt under operation conditions. Complementary, we performed X-ray photoelectron spectroscopy (XPS) before and after PEC operation to reveal chemical changes. Overall, ALD grown Pt catalysts improve the system performance compared to sputtered Pt. These measurements provide important insights into the underlying reaction mechanism and the role of surface restructuring and delamination of catalyst interfaces.

Keywords: AFM; ALD; Pt; TiO2; XPS