A parallel line probe for spatially selective electrochemical NMR spectroscopy

Area of Science:

• Electrochemistry
• Spectroscopy
• Materials Science

Background:

• In situ NMR spectroscopy is crucial for understanding electrochemical devices like batteries and reactors.
• Existing methods face limitations in spatially resolving reactions at electrode-electrolyte interfaces.
• Studying reaction intermediates and stability under electrochemical conditions requires advanced detection techniques.

Purpose of the Study:

• To develop a novel parallel line detector for spatially selective in situ electrochemical NMR spectroscopy.
• To integrate this detector into an electrochemical flow reactor, creating an 'eReactor NMR probe'.
• To demonstrate the probe's capability for selective nuclear detection at the electrode-electrolyte interface.

Main Methods:

• Fabrication of a 17-copper-wire parallel line detector, doubly tuned for 1H/19F and X nuclei.
• Integration of the detector into a high surface-to-volume electrochemical flow reactor.
• Application of B1-selective pulse sequences for spatially resolved NMR detection within 800 μm of the electrode surface.

Main Results:

• Demonstrated selective detection of 7Li and 19F nuclei in LiCl and LiBF4 electrolytes, respectively.
• Achieved good B1 homogeneity, with pulse intensity ratios between 68-72%.
• Validated operando functionality using electrochemical lithium metal plating as a model reaction.

Conclusions:

• The eReactor NMR probe provides a general and effective method for studying flow electrochemistry.
• This technology enables detailed investigation of processes at electrode-electrolyte interfaces.
• Potential applications span diverse energy systems including Li metal batteries, CO2 reduction, and fuel cells.