Activation of CO over Ultrathin Manganese Oxide Layers Grown on Au(111)
Yifan Li, Le Lin, Rentao Mu, Yijing Liu, Rankun Zhang, Chao Wang, Yanxiao Ning, Qiang Fu, Xinhe Bao
Abstract
Well-defined manganese oxide (MnOx) overlayers with a controlled chemical state and coverage were deposited on Au(111), and CO activation at the model MnOx/Au(111) surfaces was explored by combining treatments in high-pressure (up to 100 mbar) CO at elevated temperatures and in situ surface characterizations. We find that all MnOx nanostructures transformed into reduced MnO states (MnO1–y, 0 < y < 1) in the near-ambient pressure CO atmosphere, and dissociation of CO to carbon deposit occurs above 473 K. A volcano curve of the carbon deposit amount as a function of MnO coverage is clearly presented, indicating that MnO island edges are the active centers. Density functional theory calculations show that MnO/Au(111) interfaces provide edge Mn atoms coordinated with two oxygen atoms, where CO disproportionation occurs facilely through the CO dimer and further CCO* intermediates.