Standard Article

Chevrel phases and chalcogenides

Electrocatalysis

The oxygen reduction/evolution reaction

  1. N. Alonso-Vante

Published Online: 15 DEC 2010

DOI: 10.1002/9780470974001.f205041

Handbook of Fuel Cells

Handbook of Fuel Cells

How to Cite

Alonso-Vante, N. 2010. Chevrel phases and chalcogenides. Handbook of Fuel Cells. .

Author Information

  1. University of Poitiers, Laboratory of Electrocatalysis, Poitiers, France

Publication History

  1. Published Online: 15 DEC 2010

Abstract

The underlying background and present development of methanol tolerant electrocatalysts, selective for the oxygen reduction reaction (ORR), are presented. These catalysts are essentially metal-centered (ruthenium) clusters or cluster-like compounds. These clusters, partially embedded in a chalcogenide matrix (e.g., selenium) constitute the active center for the electrochemical process ORR. On well-defined cluster materials, as for example, the so-called Chevrel phases, based on octahedron clusters [(Mo2/3Ru1/3)6Se8], the ORR electrochemical activity clearly indicated that this phenomenon can be selectively sustained with a four-electron charge transfer (water formation). This is due to their electronic and geometric characteristics. Hence, clusters work as a pool of charges that can be engaged in a multi-electron process. Therefore, this family of materials served as a model for the development of novel ones. In this respect, e.g., RuxSey (x ≈ 2, y ≈ 1), tailored from chemical precursors in organic solvents, under mild conditions, shows a high dispersiveness in the nanoscale range. The metallic center shows similar electrochemical properties to those of well-defined Chevrel phases, thus behaving as a cluster-like material. The ability of the catalytic center to provide coordination chemistry for reactivity and selectivity via cluster, or cluster-like compounds is discussed, as well as the trends in the synthesis and the results of tests in half-cells and in direct methanol fuel cell systems.

Keywords:

  • Chevrel phase;
  • cluster;
  • electrocatalysis;
  • nanostructure;
  • oxygen reduction;
  • methanol tolerance;
  • chalcogenide;
  • ruthenium;
  • direct methanol fuel cell;
  • gas-diffusion electrodes