Steady state oxygenreduction and cyclic voltammetry
2008; Royal Society of Chemistry; Volume: 140; Linguagem: Inglês
10.1039/b802129e
ISSN1364-5498
AutoresJan Rossmeisl, G. S. Karlberg, Thomas F. Jaramillo, Jens K. Nørskov,
Tópico(s)Electrochemical Analysis and Applications
ResumoThe catalytic activity of Pt and Pt3Ni for the oxygen reduction reaction is investigated by applying a Sabatier model based on density functional calculations. We investigate the role of adsorbed OH on the activity, by comparing cyclic voltammetry obtained from theory with previously published experimental results with and without molecular oxygen present. We find that the simple Sabatier model predicts both the potential dependence of the OH coverage and the measured current densities seen in experiments, and that it offers an understanding of the oxygen reduction reaction (ORR) at the atomic level. To investigate kinetic effects we develop a simple kinetic model for ORR. Whereas kinetic corrections only matter close to the volcano top, an interesting outcome of the kinetic model is a first order dependence on the oxygen pressure. Importantly, the conclusion obtained from the simple Sabatier model still persists: an intermediate binding of OH corresponds to the highest catalytic activity, i.e. Pt is limited by a too strong OH binding and Pt3Ni is limited by a too weak OH binding.
Referência(s)