Activation of carbon-supported platinum nanoparticles by zeolite-type cesium salts of polyoxometallates of molybdenum and tungsten towards more efficient electrocatalytic oxidation of methanol and ethanol

The activity of Vulcan-supported Pt nanoparticles (Pt40%/Vulcan XC-72) towards oxidation of methanol and ethanol is increased by admixing them with zeolite-type cesium salts of heteropolymolybdic and heteropolytungstic acids: Cs2.5H0.5PMo12O40, Cs2.5H1.5SiMo12O40, Cs2.5H0.5PW12O40, and Cs2.5H1.5SiW12O40. It is apparent from IR measurements that these salts remain the Keggin-type structure. They are electroactive and undergo reversible redox transitions, as well as they are hydrated and contain mobile protons. As evidenced from cyclic voltammetric, stair-case voltammetric and chronoamperometric diagnostic experiments, the electrocatalytic enhancement effect has been most pronounced upon application of phosphododecamolybdate and phosphododecatungstate salts. The overall activation effect may also reflect the micro and mesoporous (zeolite-type) high surface area morphology of polyoxometallate cesium salts. The presence of well-defined polyoxometallate clusters in the vicinity of Pt is expected increase population of reactive oxo groups at the electrocatalytic interface.