Mass-transport-limited oxidation of formic acid on a PdMLPt(100) electrode in perchloric acid

•PdMLPt(100) in perchloric acid is highly active for formic acid oxidation.•On PdMLPt(100), formic acid oxidation reaches mass-transport-limited activity.•PdMLPt(100) exhibits no CO poisoning during formic acid oxidation.

In this communication, we study the electrocatalytic formic acid oxidation process on an epitaxially grown Pd monolayer on a Pt(100) single crystal in perchloric acid. The formic acid oxidation activity on this PdMLPt(100) electrode in perchloric acid is significantly enhanced compared to the same electrode in sulfuric acid and compared to unmodified Pt(100), with a low onset potential of around 0.14 VRHE. The absence of hysteresis between the positive and negative scan during formic acid oxidation indicates the remarkable resistance to CO poisoning of the Pd monolayer surface. Most importantly, we report, for the first time, a mass-transport-limited formic acid oxidation rate on the PdMLPt(100) rotating electrode in perchlorate acid, setting a catalytic benchmark for future electrocatalysts for formic acid oxidation.