Poster (After Call)

FZJ-2022-02787

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Revealing local pH gradients by in operando 13C MRI

Schatz, M. (Corresponding author)FZJ* ; Jovanovic, S.FZJ* ; Eichel, R.-A.FZJ* ; Granwehr, J.FZJ*

2022

Please use a persistent id in citations: http://hdl.handle.net/2128/32399

Abstract: The study of local reaction conditions at catalytic surfaces in an operating cell is a challenging task. In particular, the CO2 electroreduction on copper is known to be highly sensitive to local changes of pH value and electrolyte concentration. We herewith present an in operando Nuclear Magnetic Resonance technique that enables spatially and temporally resolved determination of these values using the 13C resonances of the CO2/HCO3-/CO32- equilibrium. A phase-encoding pulse sequence using spin echoes enables chemical shift resolved imaging along one spatial dimension, i.e. the longitudinal axis of a NMR tube. Placing the copper working electrode perpendicular to this axis, 13C spectra are obtained as a function of distance to the electrode. The spectral data of the CO2 and the averaged carbonate (HCO3-/CO32-) resonances are used to determine local pH and concentrations. When a constant potential is applied, increasing pH values and decreasing electrolyte concentrations are observed as a result of the consumption of H+ and CO2 from the equilibrium with HCO3-. Moreover, the presented method offers wide-ranging applicability of materials, concentrations and potentials, and it can provide additional information on chemistry and mobility of reactants.

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Contributing Institute(s):

1. Grundlagen der Elektrochemie (IEK-9)

Research Program(s):

1. 1232 - Power-based Fuels and Chemicals (POF4-123) (POF4-123)
2. DFG project 390919832 - EXC 2186: Das Fuel Science Center – Adaptive Umwandlungssysteme für erneuerbare Energie- und Kohlenstoffquellen (390919832) (390919832)

Appears in the scientific report 2022

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Database coverage:

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