Due to their activity and uniformity, atomically dispersed transition metals are highly desirable catalysts. However, sintering into larger particles is thermodynamically favorable in the absence of strong metal–support interactions. Based on density functional theory calculations, we predict that the late transition metals Pd and Pt bind strongly to oxygen vacancies of MeO (Me = Fe, Mg, Mn, and Ni), with atomic dispersion being thermodynamically favorable at low metal loadings. The binding energies increase with the oxygen defect formation energies. The resulting single atom catalysts enable CO oxidation at low temperatures, with barriers as low as 40 kJ/mol; intrinsic barriers were found to depend primarily on the nature of the transition metal. These findings are in good agreement with experimental work on Pd1/MgOX(001) catalysts by Abbet et al. (JACS 2001, 123, 6172-6178) that enable CO oxidation at 260 K. However, the Pd1/MgOX(001) catalyst is deactivated after the first oxidation step. Catalyst deactivation involves a metastable PdO/MgOX(001) species, which can heal the defect. Without the vacancy, nanoparticle formation is thermodynamically favorable. Due to their lower oxygen defect formation energies, reducible supports are predicted to be more resistant to sintering. As a result, the oxygen defect formation energy of the support is an important parameter for the stability of anionic single atom catalysts, while their activity depends primarily on the nature of the transition metal atom.

Sintering-resistant anionic single atom catalysts for O2 activation

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.