Hydrogenated Molybdenum Oxide Overlayers Formed on Mo Nitride Nanosheets in Ambient-Pressure CO/H Gases.

Transition metal nitrides (TMN) often exhibit high catalytic activity in many important reactions. Due to their low stability in a reaction environment, it remains as a crucial issue to reveal surface active structures in catalytic reactions, particularly for the cases containing both oxidative and reductive gases. Herein, MoN and MoN nanosheets have been constructed on AlO(0001) and Au foil surfaces, and surface characterizations are performed on the model catalysts in ambient-pressure CO, H, and CO + H gases. Raman spectroscopy and quasi X-ray photoelectron spectroscopy (XPS) analysis indicate that MoO and defective MoO overlayers form on both MoN and MoN surfaces in CO, and the surface oxidation occurs under a milder condition on MoN than on MoN. Further, a hydrogenated Mo oxide (HMoO) overlayer forms in a CO + H atmosphere, as confirmed using quasi XPS and time-of-flight secondary ion mass spectroscopy. The surface analysis over the model nitride catalysts suggests that O and/or H atoms may be incorporated into surface layers to form the active structure in many O and H-containing reactions.