in-situ electrochemical extended X-ray absorption fine structure spectroscopy study on the reactivation of Pd electrocatalyst in formic acid oxidation

•Study on the mechanistic origin of Pd reactivation behaviour in a formic acid oxidation.•Full recovery of electrocatalytic activity of Pd in a formic acid oxidation by cathodic bias polarization.•Extended Pd bond length providing a unfavorable structure for surface poisoning.

Palladium (Pd) has been considered as an excellent option to replace platinum-based electrocatalysts in formic acid oxidation owing to its superb catalytic activity to Pt and cheaper material price. However, unstable catalytic activity of Pd is the most critical obstacle in the development of Pd-based electrocatalysts for formic acid oxidation, and the fundamental understanding on Pd deactivation is still incomplete. In this study, the activity of deactivated Pd in a formic acid oxidation was recovered to 93% by applying a cathodic bias potential of -0.2 V vs. RHE. Based on in-situ electrochemical extended X-ray absorption fine structure spectroscopy analysis we show that cathodic polarization of Pd/C electrode could remove the adsorption of poisoning species by increasing bond length of Pd-Pd and further discuss on the origin of reactivation mechanism of Pd.

Graphical abstractin-situ EXAFS analysis shows clear change in bond length of Pd-Pd when the periodic cathodic polarization delays the deactivation of Pd in electrocatalytic oxidation of formic acid. It provides a fundamental clue to understand the origin of reactivation of Pd/C in formic acid oxidation.Figure optionsDownload full-size imageDownload as PowerPoint slide