Mechanisms for CO oxidation on Fe(iii)–OH–Pt interface: a DFT study

Abstract

The full catalytic cycle that involves the oxidation of two CO molecules is investigated here by using periodic density functional calculations. To simulate the nature of Fe(OH)_x/Pt nanoparticles, three possible structural models, i.e., Fe(OH)_x/Pt(111), Fe(OH)_x/Pt(332) and Fe(OH)_x/Pt(322), are built. We demonstrate that Fe(III)–OH–Pt stepped sites readily react with CO adsorbed nearby to directly yield CO₂ and simultaneously produce coordinatively unsaturated iron sites for O₂ activation. By contrast, the created interfacial vacancy on Fe(OH)_x/Pt(111) prefers to adsorb CO rather than O₂, thus inhabiting the catalytic cycles of CO oxidation. We suggest that such structure sensitivity can be understood in terms of the bond strengths of Fe(III)–OH.