Quantum chemical modelling of the rate determining step for oxygen reduction on quinones.
Artikel i vetenskaplig tidskrift, 2006

Two inner-sphere electrocatalytic channels for quinone-mediated reduction of molecular oxygen to form hydrogen peroxide have been addressed by means of density functional theory. Each of the channels comprises an initial rate determining chemical step and a subsequent electrochemical reduction step by which peroxide is produced. The reduction mechanism was determined for 9,10-anthraquinone and 9,10-phenanthrenequinone and the quantum chemical results are compared with experimental results. Two distinctly different structures were determined for the critical chemical step depending on whether the catalytic site is present as HQ* or Q*-. While a superoxo species is formed on HQ*, a van der Waals (vdW) type compound is formed on Q*-. It is shown that the Gibbs energy of activation for the semiquinone/oxygen reaction is largely determined by the entropy term. The results explain the experimentally observed pH dependence of the O2 reduction rate on quinone functionalised electrodes.

Quinones

chemical synthesis

Computer Simulation

Oxygen

Kinetics

Hydrogen Peroxide

Quantum Theory

Models

chemistry

Models

Chemical

Oxidation-Reduction

chemistry

Molecular

Författare

J R Tobias Johnsson Wass

University of Liverpool

Göteborgs universitet

Elisabet Ahlberg

Göteborgs universitet

Itai Panas

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

David Schiffrin

University of Liverpool

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 8 36 4189-99

Ämneskategorier

Fysikalisk kemi

DOI

10.1039/b606671b

PubMed

16971987