Time-Frequency Domain In Situ NMR: A Direct Probe into the Dynamics of Pulsed Electrocatalysis

Understanding the complex dynamics of organic electrocatalytic oxidation is essential to advancing sustainable energy technologies. This study presents an in situ methodology that integrates square-wave-pulsed electrolysis with electrochemical NMR (EC-NMR), enabling simultaneous time-domain and frequency-domain analysis to gain direct mechanistic insight into pulsed alcohol electrooxidation in alkaline media. Applied to the electrooxidation of ethanol and ethylene glycol, this approach reveals that pulsed potentials mitigate catalyst poisoning while dynamically steering the reaction pathways. The frequency-domain NMR spectra provide product speciation, demonstrating that higher and lower potentials in pulsed electrolysis could modulate the specific products. In binary mixtures, the complete oxidation of ethanol and driving ethylene glycol into valuable chemicals could be achieved. Concurrently, the time-domain NMR signals serve as real-time activity probes, directly evaluating the dynamic activity of the catalyst. This work establishes a generalizable operando analysis tool, offering a powerful means of elucidating transient kinetics and a rational framework for investigating pulsed electrocatalytic processes.