The classical way to characterize the selectivity of electrochemical reactions involves potentiostatic or galvanostatic electrolysis and intermittent product determination, for example with chromatography methods, nuclear magnetic resonance etc.^1-3 The advantage of this approach is that quantitation is possible in terms of (partial) reaction rates, yields, selectivities or faradaic efficiencies. However, the offered temporal resolution is in the order of several minutes, so transient, dynamic processes that occur
within seconds cannot be captured. Differential electrochemical mass spectrometry was previously developed to address this point and was applied successfully to a wide range of reactions that form highly volatile or gaseous products.⁴

A newly developed, internationally unique methodology will be presented that allows for the detection of electrochemical reaction products in real time, independent of their vapor pressure and the presence of salts.⁵ Some examples of applying the electrochemical real-time mass spectrometry (EC-RTMS) in multi-product electrochemical reactions such as the CO₂ reduction, the oxidation of alcohols or conversions of furanic compounds will be shown.

Acknowledgments

This work was funded by the German Federal Ministry for Education and Research (BMBF) under the project grants 033RC004C (eEthylen) and 03SFK2Z0 (Power-to-X), and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy - Excellenzcluster 2186 “The Fuel Science Center”.

References

[1] K.P. Kuhl, E.R. Cave, D.N. Abram, T.F. Jaramillo; Energy Environ. Sci. 2012, 5, 7050-7059.
[2] C.W. Li, J. Ciston, M.W. Kanan; Nature 2014, 508, 504-507.
[3] R.S. Sherbo, R.S. Delima, V.A. Chiykowski, B.P. MacLeod, C.P. Berlinguette, Nat. Catal. 2018, 1, 501-507.
[4] H. Baltruschat, J. Am. Chem. Soc. Mass Spec. 2004, 15, 1693-1706.
[5] P. Khanipour, M. Löffler, A.M. Reichert, F.T. Haase, K.J.J. Mayrhofer, I. Katsounaros; Angew. Chem. Int. Ed. accepted, DOI: 10.1002/anie.201901923