ROCK (Rocking optics for Chemical Kinetics) is the quick X-ray Absorption Spectroscopy beamline at SOLEIL synchrotron, operating in the range between 4 and 40 keV with a sub-second and micrometer resolution¹. The beamline was funded by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program to take part in the development of energy-related materials with enhanced efficiency. The ROCK beamline is thus dedicated to the study of fast chemical processes with main applications being the in situ/operando XAS characterization of catalysts and batteries in working conditions². The ROCK beamline offers a large portfolio of setups available to the scientific community and has a sound background in using chemometrics (Multivariate Curve Resolution-Alternating Least Squares, MCR-ALS) for data analysis in various scientific fields^3–5.

Photo- and electro-catalysis has gained strong interest for using in situ/operando XAS characterization to deeper understand the mechanisms involved at different stages in the catalyst life span. In that respect, we have developed versatile experimental setups dedicated to the monitoring of photo- and/or electro-catalysts behavior in working conditions via quick-XAS. X-ray absorption spectroscopy is a bulk technique, which can make it difficult to differentiate the spectator species from the active species in chemical processes such as catalysis, where the active sites are surface sites and then represent only a fraction of the total material. To overcome this bottleneck, we used the so-called modulation-excitation X-ray absorption spectroscopy (MEXAS) with phase sensitive detection (PSD) methodology to highlight the contribution of active species during a chemical process^6,7.

The capabilities of the ROCK beamlines will be presented with a specific focus on the opportunities offered in the field of photo- and/or electro-catalysis illustrated by recent examples and first results obtained on the electro-activity of layered double hydroxides^8,9 and supported metallic nanoparticles^10,11 for ethanol stream reforming under UV-visible irradiation.

1    V. Briois, C. La Fontaine, S. Belin, L. Barthe, T. Moreno, V. Pinty, A. Carcy, R. Girardot and E. Fonda, Journal of Physics: Conference Series, 2016, 712, 012149.

2    C. La Fontaine, S. Belin, L. Barthe, O. Roudenko and V. Briois, Synchrotron Radiation News, 2020, 33, 20–25.

3    A. R. Passos, C. La Fontaine, S. H. Pulcinelli, C. V. Santilli and V. Briois, Phys. Chem. Chem. Phys., 2020, 22, 18835–18848.

4    C. Lesage, E. Devers, C. Legens, G. Fernandes, O. Roudenko and V. Briois, Catalysis Today, 2019, 336, 63–73.

5    F. Eveillard, C. Gervillié, C. Taviot-Guého, F. Leroux, K. Guérin, M. T. Sougrati, S. Belin and D. Delbègue, New J. Chem., 2020, 44, 10153–10164.

6    P. Müller and I. Hermans, Ind. Eng. Chem. Res., 2017, 56, 1123–1136.

7    A. Urakawa, D. Ferri and R. J. G. Nuguid, in Springer Handbook of Advanced Catalyst Characterization, eds. I. E. Wachs and M. A. Bañares, Springer International Publishing, Cham, 2023, pp. 967–977.

8    H. Farhat, C. Taviot-Gueho, G. Monier, V. Briois, C. Forano and C. Mousty, J. Phys. Chem. C, 2020, 124, 15585–15599.

9    H. Farhat, 2021, Thèse de doctorat de l'université de Clermont-Ferrand.

10  A. Pérez Alonso, S. Mauriés, J. Ledeuil, L. Madec, D. Pham Minh, D. Pla and M. Gómez, ChemCatChem, 2022, 14, e202200775.

11  E. Mamontova, C. Trabbia, I. Favier, A. Serrano-Maldonado, J.-B. Ledeuil, L. Madec, M. Gómez and D. Pla, Nanomaterials, 2023, 13, 1435.