Phosphomolybdic acid supported atomically dispersed transition metal atoms (M = Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au): stable single atom catalysts studied by density functional theory

By means of first-principles calculations, the interaction of twelve different transition metal atoms (M 1⁄4 Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au) of groups VIII–XI with phosphomolybdic acid (H3PMo12O40, PMA), a newly emerging medium for trapping transition metal atoms, has been systematically investigated. The M–PMA systems have very high stability with the binding energies of transition metals higher than those on widely used metal oxide supports. The high diffusion barriers of these single metal atoms on the PMA surfaces suggest that they are sufficiently stable to prevent agglomeration. Based on the electronic structure analysis, the remarkable stability of single atoms is attributed to the strong mixing between the d orbitals of the metal atom and 2p orbitals of PMA oxygens, which results in electron transfer from the metal atoms to PMA, producing positively charged single metal atoms which can be used for catalytic applications. Finally, we test the activity of Pt–PMA as a low-cost, stable, and efficient catalysts for CO oxidation. This work is expected to provide useful insight to the development of new highly efficient heterogeneous single atom catalysts (SACs).