Intermediates Arising from the Water–Gas Shift Reaction over Cu Surfaces: From UHV to Near Atmospheric Pressures

Probing Water Dissociation and Oxygen Replacement on Partially Oxygen-Covered Cu(111) by Reflection Absorption Infrared Spectroscopy

The presence of chemisorbed oxygen on the Cu(111) surface is known to strongly reduce the activation barrier for water dissociation as compared to bare Cu(111). Here, we present direct experimental evidence for the hydrogen abstraction mechanism responsible for the facile H2O dissociation on an O/Cu(111) surface using reflection absorption infrared spectroscopy (RAIRS) in combination with isotopically labeled reactants. We also observe that chemisorbed hydroxyl species produced by water dissociation on the O/Cu(111) surface undergo an efficient hydrogen atom transfer from trapped water molecules, leading to the rapid replacement of the initial oxygen isotope coverage and the detection of only a single hydroxyl isotopologue on the surface, in apparent contradiction with the hydrogen abstraction mechanism. In the presence of Cu2O oxide islands on the O/Cu(111) surface, water dissociation occurs selectively at the edges of those islands, leading to the self-assembly of isotopically ordered structures.

Cu-Y2O3 Catalyst Derived from Cu2Y2O5 Perovskite for Water Gas Shift Reaction: The Effect of Reduction Temperature

Cu2Y2O5 perovskite was reduced at different temperatures under H2 atmosphere to prepare two Cu-Y2O3 catalysts. The results of the activity test indicated that the Cu-Y2O3 catalyst after H2-reduction at 500 °C (RCYO-500) exhibited the best performance in the temperature range from 100 to 180 °C for water gas shift (WGS) reaction, with a CO conversion of 57.30% and H2 production of 30.67 μmol·gcat−1·min−1 at 160 °C and a gas hourly space velocity (GHSV) of 6000 mL·gcat−1·h−1. The catalyst reduced at 320 °C (RCYO-320) performed best at the temperature range from 180 to 250 °C, which achieved 86.44% CO conversion and 54.73 μmol·gcat−1·min−1 H2 production at 250 °C. Both of the Cu-Y2O3 catalysts had similar structures including Cu°, Cu+, oxygen vacancies (Vo) on the Cu°-Cu+ interface and Y2O3 support. RCYO-500, with a mainly exposed Cu° (100) facet, was active in the low-temperature WGS reaction, while the WGS activity of RCYO-320, which mainly exposed the Cu° (111) facet, was greatly enhanced above 180 °C. Different Cu° facets have different abilities to absorb H2O and then dissociate it to form hydroxyl groups, which is the main step affecting the catalytic rate of the WGS reaction.

Water facilitates oxygen migration on gold surfaces

Oxygen exchange between surface oxygen atom and isotopic labeled water vapor through transient hydroxyl pairs on Au(110) surface.

Ambient pressure XPS and IRRAS investigation of ethanol steam reforming on Ni–CeO2(111) catalysts: an in situ study of C–C and O–H bond scission

In situ investigation of the surface chemistry of ethanol steam reforming & metal-oxide interactions over Ni–CeOx(111).