Importance of Support and Interactions with Noble Metal Nanocenters in Electrocatalysis
The problem of oxygen reduction is even more severe case of alcohol-utilizing fuel cells. In this respect, heat-treated carbon-supported macrocyclic complexes and their derivatives as well as chalcogen modified transition metals are promising and selective (e.g. methanol tolerant) platinum-free catalysts for oxygen reduction.
Our research interests also concern development of electrocatalytic systems for the reduction of carbon dioxide. For example, as catalytic materials commercial palladium nanoparticles and the macromolecular complex of palladium, namely [Pd(C14H12N2O3)Cl2]2∙MeOH, were considered. The electrochemical data clearly imply that the process of electroreduction of carbon dioxide begins at the less negative potentials when pursued at the palladium complex in addition to the significant enhancement of the net (background-subtracted) CO2-reduction current densities relative to those observed at conventional nanostructured palladium. Among important issues are specific interactions between nitrogen coordinating centers and electrogenerated metallic palladium sites at the electrocatalytic interface.
We have interest in the better understanding and controlling of electrocatalytic phenomena appearing in the direct alcohol fuel cells as alternative technology to hydrogen based electrochemical energy systems. The most common Pt anodes are readily poisoned by the strongly adsorbed intermediates, namely by CO-type species, requiring fairly high overpotentials for their removal. We have recently demonstrated that catalytic activity of platinum-based nanoparticles towards electrooxidation of ethanol has been significantly enhanced through interfacial modification with ultra-thin monolayer-type films of polyoxometallates particularly heteropolymolybdates. Also gold in combination with platinum has been demonstrated to produce novel high performance bimetallic catalysts. We are going to describe here a concept of utilization of functionalized or mixed titanium dioxide, tungsten oxide or zirconium oxide matrices for supporting and activating noble metal nanoparticles (Pt, Pt-Ru or Pt-Rh) during electrooxidation of ethanol. We are going to consider protonically/electronically conducting zeolite-type cesium salts of Keggin-type heteropolyacids of molybdenum and tungsten as matrices for Vulcan-supported Pt, PtRu and PtSn nanoparticles during electrooxidation of methanol and ethanol.