Formic acid oxidation on Palladium

The combination of two catalytic elements was realized in a study of formic acid oxidation on Pt(lOO) and Pt(lll) modified by the adsorption of palladium [Pdaj + Pt(lOO) and Pdjd + Pt(lll) systems]. While the presence of adsorbed palladium on Pt(lOO) resulted in a considerable lowering of the oxidation potential and the absence of self-poisoning under open circuit conditions, the activity of Pt(lll) substrate did not change significantly by Pd adsorption. However, a deactivation of the Pdaj + Pt(lOO) system is observed when the oxidation of formic acid takes place. This deactivation is analyzed in terms of slow formation of an adsorbed species blocking the initial step of formic acid oxidation on palladium sites. 

An astonishing aspect of formic acid oxidation on palladium is the formation of CO2 at potentials of hydrogen oxidation and oxygen evolution. On-line mass spectroscopy analysis of volatile products reveals the production of CO2 not only in the double-layer region but also near 0.25 and 1.75 V [101]. The fact that the current and the CO mass signal during a potential scan do not follow the same pattern indicates that HCOOH oxidation proceeds through parallel mechanisms. 

Solis V, Iwasita T, Pavese A et al (1988) Investigation of formic acid oxidation on palladium in acidic solutions by on-line mass spectroscopy. J Electroanal Chem Interfacial Electrochem 255 155-162... 

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