Initial Growth and Oxygen Adsorption of Silver on Al₂O₃ Film

Abstract

The growth and oxygen adsorption of Ag on an ordered Al2O3 film, prepared on Mo(110) substrate, have been studied in situ under ultrahigh-vacuum condition using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The results show that Ag particles/clusters are formed on alumina film at initial coverages, and the binding energy of the Ag 3d5/2 line for Ag clusters is higher than that of bulk Ag, arisen from the size effect. Exposure of Ag clusters to ∼10-7 mbar O2 leads the clusters to spreading over the substrate. It is of importance in many application areas to understand the origin of oxygen-induced metal-cluster changes in morphology and size.

On the performance of Ag/Al2O3as a HC-SCR catalyst – influence of silver loading, morphology and nature of the reductant

“…This is supported by the shift towards higher binding energies (BE) for the 2 wt% sample, compared to the 6 wt% sample. 25,49 As reported by Guo et al, 49 small silver clusters on alumina shift towards higher BE when treated with oxygen. Furthermore, during the HC-SCR reaction the surface of the catalyst is continuously reduced and re-oxidized, as different gas phase species adsorbs and reacts, making it difficult to determine the exact oxidation state of silver.…”

“…Such experimental observations indicate that the low-coordinated step sites could be possible sites for oxygen adsorption and dissociation leading to hydrocarbon oxidation or they could be the sites responsible for breaking of the C-H (or C-C) bond, which is an important step in the mechanism. 49,50 As the temperature is further increased to 500 1C, some interesting observations are made. First, at 500 1C the 2 wt% catalyst becomes more active in terms of global NO x reduction than the 6 wt% sample.…”

Aspects of the Role of Hydrogen in H2-Assisted HC–SCR Over Ag–Al2O3

“…Based on the work of Guo et al [28], we propose in a recent study [14] that the XPS results thus indicate that small silver clusters exist on the catalyst surface. Due to the size effect, the BE shift for the reduced silver clusters is opposite to the BE shift for bulk silver [28]. This leads to an apparent oxidation of the sample surface after pre-reduction with hydrogen.…”

A Novel Anode with Superior Cycling Stability Based on Silicon Encapsulated in Shell‐Like rGO/CNT Architecture for Lithium‐Ion Batteries

“…In cooperation with additional network of CNTs, a rapid electron transfer was ensured during the electrochemical process without distortion of the electrode, thus reducing the overall resistance of the half-cell. [39] The above results indicate that additive CNTs successfully supplied efficient and sustainable conductive pathways.…”