Standard Article

First-principles modeling for the electro-oxidation of small molecules

Advances in Electrocatalysis, Materials, Diagnostics and Durability

Electrocatalyst materials for low temperature fuel cells

Fundamental catalysis models

  1. M. Neurock

Published Online: 15 DEC 2010

DOI: 10.1002/9780470974001.f500010

Handbook of Fuel Cells

Handbook of Fuel Cells

How to Cite

Neurock, M. 2010. First-principles modeling for the electro-oxidation of small molecules. Handbook of Fuel Cells. .

Author Information

  1. University of Virginia, Charlottesville, VA, USA

Publication History

  1. Published Online: 15 DEC 2010

Abstract

The electrocatalytic oxidation of small organic molecules is of great interest in the development of direct liquid fuel cells. While much is known concerning the overall electrocatalytic chemistry, the mechanisms and active sites which control these reactions remain elusive. The advances that have taken place in computation together with new method developments have made theory an invaluable partner with experiment in elucidating the mechanisms and sites that control electrocatalysis. Recent advances in ab initio methods for modeling electrochemical systems and their application to modeling the oxidation of methanol, formic acid and ethanol are discussed herein. The results reveal that while each of these fuels can be oxidized via direct and indirect routes, the controlling paths are function of the molecule as well as the size and configuration of the active surface sites. Methanol proceeds via indirect oxidation paths which require ensemble sizes of at least 3 metal atoms. Formic acid which internally contains CO2 proceeds instead via a direct path over just 1–2 metal atoms. Ethanol is oxidized primarily to acetaldehyde and acetic acid and requires the presence of defect sites to activate the C[BOND]C bond. The unique nature of the active site for each of these fuels reveals different alloying effects.

Keywords:

  • Ab initio density functional theory (DFT);
  • electrocatalytic oxidation mechanisms;
  • ensemble size effects