The Mechanism of Low‐Temperature CO Oxidation on IB Group Metals and Metal Oxides

Abstract

CO oxidation on the IB group metals [Cu(111), Ag(111), and Au(111)] and corresponding metal oxides [Cu2O(100), Ag2O(100), and Au2O(100)] has been studied by means of density functional theory calculations with the aim to shed light on the reaction mechanism and catalytic activity of metals and metal oxides. The calculated results show that 1) the molecular oxygen mechanism is favored on Ag(111) and Au(111), but the atomic oxygen mechanism is favored on Cu(111); 2) the metal‐terminated metal oxide shows very low activity for CO oxidation; 3) the lattice oxygen can react either with gas phase CO or the absorbed CO molecule on oxygen‐terminated metal oxides; and 4) the reaction barrier for CO oxidation follows the order of M2O(100)–O<M(111)<M2O(100)–M (M=Cu, Ag, Au); namely the M2O(100)–O shows higher activity than does the corresponding metal. By analyzing the factor that controls the energy barrier, it was found that the interaction energy between two CO molecules and one O atom at the transition state plays an important role in determining the trend in the barrier.

Cluster-Size-Dependent Interaction between Ethylene and CuCl2 Clusters Supported via γ-Alumina

“…The short d-band center (ε d ) of copper atoms was calculated to explain the size-dependent ethylene adsorption on the small-sized clusters (i.e., CuCl 2 and (CuCl 2 ) 2 on γ-Al 2 O 3 (110) and ( 100)) since it was demonstrated to better characterize the reactivity of metal oxides and metal carbides compared to the infinite d-band center. 38,39 It is defined as…”

Role of Nanointerfaces in Cu‐ and Cu+Au‐Based Near‐Ambient‐Temperature CO Oxidation Catalysts

“…[10][11][12][13][14][15][16] The mechanism behind the low temperature activity and the state of gold is, however, yet to be settled and current proposals remain controversial. [16,17] Our literature search reveals that there are not many nongold-based ambient or near-ambient oxidation catalysts available. [18][19][20] There are claims for the nanogold surface state to be either zero valent, anionic, or cationic, and evidence has been presented for all those oxidation states.…”

“…[18][19][20] There are claims for the nanogold surface state to be either zero valent, anionic, or cationic, and evidence has been presented for all those oxidation states. [5,17] This is further complicated by different preparation procedures followed by different groups, and the nature of support also exhibits a significant role in the catalytic CO oxidation. [11,13,21] Generally, nanogold on reducible supports, such as titania, exhibits the best CO oxidation activity at ambient temperature.…”

Facile Solvothermal Strategy to Construct Core–Shell Al2O3@CuO Submicrospheres with Improved Catalytic Activity for CO Oxidation

“…Catalytic oxidation of CO to less toxic CO 2 has been intensively investigated owing to its important industrial applications, such as chemical processing, CO 2 lasers, sensors, fuel cell technology, and car‐exhaust emission control, as well as a prototypical reaction to explore heterogeneous catalysis 1. 2 Until now, various types of nanocatalysts have been developed for catalytic CO oxidation and can be generally classified into three categories according to the active components: 1) noble metal nanocatalysts (e.g., Au, Pt, and Pd),3–5 2) non‐noble metal nanocatalysts (e.g., Cu, Ni),6, 7 and 3) transition metal oxides (e.g., CuO, Cu 2 O, CeO 2 , Co 3 O 4 , and TiO 2 ) 8–12. Generally, catalysts of the first two categories are relatively costly and are easily deactivated due to the migration and sintering of nanoparticles (NPs) into larger particles,13, 14 while those of the latter category are cheap and also have comparable activities as noble metal catalysts for CO oxidation 15–18.…”