CO oxidation by the atomic oxygen on silver clusters: structurally dependent mechanisms generating free or chemically bonded CO2. Issue 1 (30th November 2016)

• Record Type: Journal Article
• Authors: Cao, Xizi; Chen, Mengyi; Ma, Jun; Yin, Baoqi; Xing, Xiaopeng
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 1(2017)
• Page Start: 196
• Page End: 203
• Publication Date: 2016-11-30
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp06741g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Oxidation of CO by the atomic oxygen on Ag n O − ( n = 1–8) forms free or chemically bonded CO2 . Abstract : Atomic oxygen on silver is the crucial active species in many catalytic oxidation processes, while it is a big challenge to explore the relationship between its activity and molecular-level structures in condensed phases. We carried out kinetic measurements of the gas phase reactions between Ag n O − ( n = 1–8) and CO, in which the oxygen atoms were predicted to be terminal ones in AgO − and Ag2 O −, in quasi-Ag–O–Ag chains for Ag3 O − and Ag4 O −, and on the two-fold or three-fold bridging positions in Ag n O − ( n = 5–8). All these oxygen species are highly reactive even at a low temperature of 150 K. Ag n O − ( n = 1, 2, 5–8) with terminal or bridging oxygen generate free CO2, while the quasi-chains of Ag n O − ( n = 3, 4) generate chemically bonded CO2 with a structural formula of Ag n –CO2 –Ag2 − ( n = 1, 2). Density functional theory calculations well interpreted all experimental observations, showing that no extra excitation energies are needed to initiate all these reactions. The structurally dependent mechanisms and the formation of chemically bonded CO2 revealed in this work help us to catch a glimpse of some important processes and intermediates on real silver catalysts.