DFT Study on CO Catalytic Oxidation Mechanism on the Defective Cu₂O(111) Surface

Abstract

Understanding the role of surface defects on the catalyst performance is of great significance for a good command of the catalytic mechanism on the real catalyst surface. This work reports the mechanistic study of CO oxidation on the defective Cu 2 O(111) surface using density functional theory calculations. The effect of surface defects on surface catalytic activity was investigated by creating surface-adsorbed O atoms and Cu vacancies on the perfect Cu 2 O(111) surface. Possible defective surface structures were found, and calculated results showed that Cu vacancy on the Cu 2 O(111) surface could promote CO oxidation in two ways by (I) promoting the reaction between CO and lattice O with the energy barrier of 1.316 eV following the Mars−van− Krevelen mechanism; (II) promoting the reaction between CO and adsorbed O atoms below 575 K. For the perfect Cu 2 O(111) surface, adding adsorbed O to the surface could either cause a strong surface reconstruction with the adsorbed O evolving into a lattice O or stay in the active state. The obtained results could explain the experimental observations that a higher O/Cu ratio on the Cu 2 O surface can improve the activity of Cu 2 O toward CO oxidation. Rate constants were provided according to harmonic transition state theory, which would be helpful for the kinetic modeling of CO catalytic oxidation on the real Cu 2 O surface.

First-Principles Study of NO Reduction by CO on Cu2O(110) and Pd1/Cu2O(110) Surfaces

“…As an important semiconductor, cuprous oxide (Cu 2 O) has been widely used in several important catalytic reactions, such as CO oxidation, 27−29 methanol synthesis, 30,31 water−gas conversion reactions, 32,33 and NO x conversion. 16,20,27 Recent experimental studies show that different surface facets of Cu 2 O nanocrystals have different activities for NO reduction by CO. 20,27 Gao et al 20 facets and cubes with exposed (100) facets. It is observed that the main product is N 2 O at low temperature, while with the increases of temperature, N 2 , which is mainly produced by N 2 O decomposition, becomes the major product.…”

“…As for CuO, it is speculated that Cu 2 O is formed by the reduction of CuO by CO and acts as a catalyst for the NO + CO reaction. ,,, Therefore, the focus of this study is Cu 2 O. As an important semiconductor, cuprous oxide (Cu 2 O) has been widely used in several important catalytic reactions, such as CO oxidation, − methanol synthesis, , water–gas conversion reactions, , and NO x conversion. ,, Recent experimental studies show that different surface facets of Cu 2 O nanocrystals have different activities for NO reduction by CO. , Gao et al found that among the three main exposed low-index crystal planes (110), (111), and (100) of Cu 2 O, rhombic dodecahedral nanocrystals with exposed (110) facets possess better catalytic performance for NO reduction by CO than octahedrons with exposed (111) facets and cubes with exposed (100) facets. It is observed that the main product is N 2 O at low temperature, while with the increases of temperature, N 2 , which is mainly produced by N 2 O decomposition, becomes the major product.…”

Dissociative adsorption modes of TATB on the Al (111) surface: a DFT investigation

“…The undissociated N-H and N-O bonds are elongated to 1.032-1.069 A and 1.256-1.498Å, respectively, which is because the N and O atoms interact actively with the adjacent Al atoms. 36 The corresponding adsorption energy of 6V is À1383.32 kJ mol À1 , which is the highest energy in the vertical adsorption systems. 5V exhibits the C-C symmetric axis of the TATB molecule above the bridge site between the three layers of the Al surface.…”

Dicopper Dioxygenase Model Immobilized in Mesoporous Silica Nanoparticles for Toluene Oxidation: A Mechanism to Harness Both O Atoms of O2 for Catalysis

“…Here, we describe a kinetic and mechanistic study on the reaction illustrated in Scheme in order to develop an understanding of how this dicopper system carries out this interesting and unique chemistry. Since the catalytic cycle for the oxidation under consideration is analogous to the Mars-van-Krevelen mechanism for O 2 activation and replacement of the lattice oxygen atoms in heterogeneous metal-oxide-catalyzed oxidations at high temperatures, − the outcome of the present study on a well-defined heterogenized system can bridge our understanding between heterogeneous and homogeneous oxidation of C–H bonds mediated by copper-oxo species.…”