In situ monitoring multi-carbon alcohol oxidation by combined electrochemistry with spatially selective NMR spectroscopy

Abstract

In situ electrochemical nuclear magnetic resonance (EC-NMR) plays a pivotal role in electrochemical observation on liquid fuel cells, but its applications are generally trapped by insufficient spectral resolution caused by spatiotemporal variations of magnetic fields. Herein, we develop a general spectroelectrochemistry protocol to address this problem and facilitate real-time electrooxidation analyses. This protocol enables the direct extraction of well-resolved and undistorted NMR signals from standard NMR instruments, thus it is commonly applicable to in situ electrochemical studies. The effectiveness for electrooxidation mechanism investigations on multi-carbon alcohols is validated by 1-butanol electrooxidation. It is verified that the direct oxidation of 1-butanol to butyric acid becomes more significant along with higher potentials on Pt/C at 60 °C, while 1-butanol oxidation is more likely to yield gaseous products (mainly CO₂) at lower potentials. Additionally, this protocol reveals that Pt/C rather than PtRu/C is inclined to accomplish the β -C–H bond breaking process for CO₂ generation at a high potential of 1.2 V (vs. SCE) . Therefore, this study provides a promising paradigm for electrooxidation investigations on fuel cells, and it may take a meaningful step toward wider electrochemical studies and NMR applications.