26–30 Aug 2024
Europe/Berlin timezone

Real-Time Observation of Intermediates at the Solid-liquid Interface of Catalyst Electrode Using Wavelength-Dispersive Soft X-ray Absorption Spectroscopy

29 Aug 2024, 17:30
15m
Saal E

Saal E

Contributed talk 12. Time resolved techniques Mikrosymposium 12/2: Time Resolved Techniques

Speaker

Kaoruho Sakata (High Energy Accelerator Research Organization)

Description

A real-time measurement method by soft X-ray absorption spectroscopy (XAS) was developed to observe the chemical reaction under operando condition [1]. In addition, a dedicated cell for the method was prepared for real-time observation of the chemical reaction at the solid-liquid interface of the (photo)electrode for the oxygen evolution reaction (OER) of water electrolysis. Hydrogen generation through water electrolysis is one of the most popular research fields for achieving carbon neutrality. In particular, the electrode for OER is a performance bottleneck compared with the hydrogen evolution reaction electrode; therefore, improving the OER performance is important for enhancing the overall system performance. For the purpose, operando evaluation focusing on the solid–liquid interface conditions is key to elucidating the chemical states of the catalytic material surface and identifying the intermediate species at the surface.
In this study, CoOx and TiO2 as OER catalysts were observed in real time using fluorescence-yield soft X-ray XAS. Oxygen K-edge XAS was observed during linear sweep voltammetry for OER, and with UV light on or off (in the case of TiO2). The spectra during the reaction were obtained every 3 s. Alternation of the spectra appeared during the potential sweep, and the peak intensity differed between the cases with UV light on and off for TiO2. This spectral change can be attributed to the intermediates formed during the (photo)catalytic reaction at the solid–liquid interface.
The present technique can be applied to a wide range of analyses of (photo-) electrocatalysis and electrochemical reactions at solid–liquid interfaces to observe their products and intermediates during the reaction.

Figure 1 Schematic image of the dedicated electrochemical cell for measurement using wavelength-dispersive XAS. The XAS spectra of O K-edge were obtained in real time, and the spectrum changed according to the applied potential. The right side of the figure shows the change in intensity of O K-edge of CoOx over time during the potential sweep. [2], [3]

References:
[1] K. Amemiya et al., Rev. Sci. Instrum. 91, 093104 (2020).
[2] K. Sakata, K. Amemiya, Chem. Lett. 50, 1710 (2021).
[3] K. Sakata, K. Amemiya, Electrochem. Commun. 157, 107627 (2023).

I plan to submit also conference proceedings No

Primary author

Kaoruho Sakata (High Energy Accelerator Research Organization)

Co-author

Prof. Kenta Amemiya (KEK-IMSS)

Presentation materials