Ambient Pressure X-ray Photoelectron Spectroscopy Study of Oxidation Phase Transitions on Cu(111) and Cu(110).

The surface structure effect on the oxidation of Cu has been investigated by performing ambient-pressure X-ray photoelectron spectroscopy (APXPS) on Cu(111) and Cu(110) surfaces under oxygen pressures ranging from 10 to 1 mbar and temperatures from 300 to 750 K. The APXPS results show a subsequential phase transition from chemisorbed O/Cu overlayer to Cu O and then to CuO on both surfaces. For a given temperature, the oxygen pressure needed to induce initial formation of Cu O on Cu(110) is about two orders of magnitude greater than that on Cu(111), which is in contrast with the facile formation of O/Cu overlayer on clean Cu(110).

CO Activation on Ni(111) and Ni(110) Surfaces in the Presence of Hydrogen.

The structure sensitivity of CO activation in the presence of H has been identified by ambient-pressure X-ray photoelectron spectroscopy (APXPS) on Ni(111) and Ni(110) surfaces under identical reaction conditions. Based on the APXPS results and computer simulations, we propose that, around room temperature, the hydrogen-assisted activation of CO is the major reaction path on Ni(111), while the redox pathway of CO prevails on Ni(110). With increasing temperature, the two activation pathways are activated in parallel.

Sustainable methane utilization technology via photocatalytic halogenation with alkali halides.

Methyl halides are versatile platform molecules, which have been widely adopted as precursors for producing value-added chemicals and fuels. Despite their high importance, the green and economical synthesis of the methyl halides remains challenging. Here we demonstrate sustainable and efficient photocatalytic methane halogenation for methyl halide production over copper-doped titania using alkali halides as a widely available and noncorrosive halogenation agent.

Fine cubic CuO nanocrystals as highly selective catalyst for propylene epoxidation with molecular oxygen.

Propylene epoxidation with O to propylene oxide is a very valuable reaction but remains as a long-standing challenge due to unavailable efficient catalysts with high selectivity. Herein, we successfully explore 27 nm-sized cubic CuO nanocrystals enclosed with {100} faces and {110} edges as a highly selective catalyst for propylene epoxidation with O, which acquires propylene oxide selectivity of more than 80% at 90-110 °C. Propylene epoxidation with weakly-adsorbed O species at the {110} edge sites exhibits a low barrier and is the dominant reaction occurring at low reaction temperatures, leading to the high propylene oxide selectivity.