Efficient and selective activation of molecular oxygen at mild conditions is important for chemical transformations and energy conversion. Here we find a Cu(I/II) single-site on CeO2 surface for oxygen activation. The oxidative nature of Ce4+ helps stabilize the Cu(I/II) site and reduces the energy of the frontier orbitals. These single-sites are 10 times more active than CuO clusters in CO oxidation, showing a turnover frequency of 0.028 ± 0.003 s-1 at 373 K and 0.01 bar PCO. Operando XAFS, EPR, AP-NEXAFS and density functional theory simulations reveal the dynamic transition between [Cu(I)O2]3- and a possible peroxide species [Cu(II)O2(h2-O2)]4- in CO rich and lean conditions, indicating the redox mechanism during the reaction. The Cu(I/II) single-site shows superior styrene epoxidation activity with molecular O2, giving styrene oxide with 57% selectivity at 373 K.

Adsorption and activation of O2 over Cu single-site over ceria surface

2019 Fall National Meeting

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