@article {44536,
	title = {Subtle interaction between Ag and O 2 : a near ambient pressure UV photoelectron spectroscopy (NAP-UPS) investigations},
	journal = {Journal of Chemical Sciences},
	volume = {130},
	year = {2018},
	month = {MAR},
	pages = {30},
	type = {Journal Article},
	abstract = {The Ag-O2 interaction, which is at the center-stage of Ag-catalyzed partial oxidation reactions, is
studied with NAP-UPS up to 0.2 mbar O2 pressure between 295 and 550 K. Three temperature regimes were
identified for distinct Ag-O2 interaction, which are (a) 295{\textendash}390 K, where mainly dissociative chemisorption of
O2 happens, (b) 390{\textendash}450 K, where diffusion of O-atoms into the sub-surfaces of Ag is prominent, and (c) >450
K, where metastable oxide forms on polycrystalline Ag surfaces. The work function (WF) of Ag changed from
4.95 (<=390 K) to 5.30 eV (390{\textendash}450 K), and then to 5.7 eV (>=450 K) at 0.1 mbar O2 pressure. Oxygen population
in the sub-surfaces imparts crucial modifications to Ag at 390{\textendash}450 K; it makes the surface to be electron-deficient
that relates to the change in the WF of Ag and facilitates the formation of space charge layer on Ag surface.
Oxygen adsorbed on such modified Ag-surfaces is electrophilic in nature, and this appears at a higher binding
energy in core level XPS than the chemisorbed oxygen on metallic Ag. This is supported by angle-dependent
NAP-XPS studies. The subsurface population of oxygen in Ag no longer persists at >410 K when the O2 supply
is removed. A high ratio of antibonding/bonding O 2p bands suggests the unique silver-oxygen interaction under
the measurement conditions.},
	keywords = {Electronic Structure, epoxidation, heterogeneous catalysis, Surface Science},
	issn = {9743626},
	doi = {10.1007/s12039-018-1434-3},
	author = {Ghosalya, Manoj Kumar},
	editor = {Reddy, Kasala Prabhakar}
}
