P-050

Anna Chmielnicka

achmielnicka@chem.uw.edu.pl

Aldona Kostuch, Enrico Negro, Gioelle Pagot, Vito Di Noto, Iwona A. Rutkowska, Pawel J. Kulesza

Faculty of Chemistry, University of Warsaw, Poland

Copper-containing-tungsten-oxide-additive as cocatalyst for low-Pt-content-system for oxygen reduction

The proton-exchange membrane fuel cell (PEMFC) technology is one of the most promising approaches for energy conversion in automotive applications. Many current research studies have been devoted to the optimization of Pt active centers and maximization of their utilization, which should allow the lowering of the costly Pt loadings without loss of performance and durability. Unfortunately, the problem of electrochemical stability and the danger of generation of higher quantities of the undesirable hydrogen peroxide intermediate may become even more serious in the case of systems utilizing lower amounts of the Pt catalyst.

Among important strategies is the hybridization, activation, and stabilization of carbon-supported Pt catalysts by functionalization through admixing with certain nanostructured and typically substoichiometric metal oxides. Special attention is paid to application of the bi- or multi-metallic Pt-based alloys in their various forms and structures. Among other important issues are such features as porosity, hydrophilicity, and degree of graphitization of carbon components, in addition to the existence of metal–support interactions, high electrochemical active surface area, electronic structure of interfacial Pt, and the feasibility of adsorptive or activating interactions with oxygen molecules. Hybrid supports, which utilize metal oxides (e.g., CeO2, WO3, or ZrO2) have been demonstrated to stabilize Pt and carbon nanostructures and diminish their corrosion while exhibiting high activity toward the four-electron (most efficient) reduction of oxygen. In the present work, we explore and demonstrate usefulness of copper-intercalated hexagonal tungsten oxide as cocatalyst or additive to the Vulcan supported Pt and PtCu nanoparticles. Based on XPS measurements, specific interactions between Pt and hybrid metal oxide centers can be postulated.

The rotating ring-disk electrode (RRDE) methodology, are typically applied to diagnose mechanisms and dynamics of ORR. A tempting alternative for recording the electrochemical responses is to integrate the current and to report charge passed as a function of time. Chronocoulometry offers important advantages including good signal-to-noise ratio because the act of integration smooths random noise on the current transients. Furthermore, by integrating the responses, it is possible to separate surface phenomena (e.g. interfacial oxidation of carbon or platinum) more readily from bulk electrochemical responses.