Formic Acid Oxidation at Pd, Pt and PbOx-based Catalysts and Calculation of their Approximate Electrochemical Active Areas

In this work, we describe the use of several Pd-based catalysts for promotion of the oxidation of formic acid in the presence of sulphuric acid. We also undertake and discuss a calculation of the "electrochemical area" of the carbon-supported catalysts, by using a polycrystalline Pt electrode and a Fe(CN)(6)(3-)/Fe(CN)(6)(4-) solution. All catalysts were synthesized by a modified sol-gel method. XRD spectra revealed that the Pd/C catalyst particles were a mixture of Pd and PdO crystallites. Particles of the Pd-Pt/C catalyst were composed mainly of a mixture of Pd, Pt or PdPt crystallites. The Pd-Pt-PbOx/C particles were a mixture of crystallites of Pd, Pt (or PdPt), PdO and lead oxides. Examination of their electrochemical responses showed that the Pd-Pt-PbOx/C catalysts are well suited to promote formic acid oxidation, as they avoid strong ion adsorption processes on the electrode surfaces, a problem commonly observed when using Pd/C catalysts.