Deactivation resistant Pd–ZrO2 supported on multiwall carbon nanotubes catalyst for direct formic acid fuel cells

One of the main problems of palladium based catalysts for a direct formic acid fuel cell (DFAFC) is their low stability during a long-term operation. In these studies, the Pd-ZrO2 catalyst supported on the multiwall carbon nanotubes (MWCNTs) was prepared and thermo-chemically treated. These catalysts were tested in a fuel cell for formic acid electrooxidation, and their chemical composition and structure were characterised by the XPS, STEM, HR-TEM and XRD techniques. It was found that the Pd-ZrO2/MWCNTs catalyst after synthesis causes oscillations of the cell voltage during operation resulting in significantly higher deactivation resistance than that of Pd/MWCNTs. This may be attributed to the "self-cleaning" mechanism of poisoned Pd catalyst by carbon monoxide through the electrochemical oxidation of COads (adsorbed) to CO2 (gas).