Potential dependence of CO oxidation by H2O on a Pt anode. A molecular orbital theory

Abstract

The electrochemical oxidation of CO on Pt anodes by water has been studied with the atom superposition and electron delocalization molecular orbital (ASED-MO) theory. By using a Pt cluster to represent the Pt(111) surface and then shifting the Pt valence band down in energy to represent the result of applying a positive potential to the electrode, a potential step for the overall anodic process H2O + CO → CO2 + 2H+ + 2e- has been found. This corresponds to the debonding of an H2O ·· CO intermediate from the electrode surface with the simultaneous loss of 2H+ to the solution and 2e- to the anode, releasing CO2. Formation of this intermediate itself is calculated to have an activation barrier with insignificant potential dependence. © 1992.