On the origin of reactive Pd catalyst for anelectrooxidation of formic acid

We investigated the reactivation of Pd catalysts during the electrocatalytic oxidation of formic acid. Pd catalyst was electrochemically deposited onto carbon paper substrate that was characterized by XRD, SEM, and XPS. Pd catalysts showed fast deactivation, though their activity could be simply recovered by applying a reduction potential at which hydrogen generation can occur. XPS results revealed that the surface of Pd catalysts is significantly affected by interaction with formic acid. High coverage of formic acid and/or formate is found at active state of Pd catalyst and diminished as deactivation proceeds. We concluded that cathodic polarization may remove poisoning species on the Pd electrode and form an active site for formic acid oxidation. This reactivation method can sustain a durability of Pd catalysts