CuO Surface Research Articles

Self-assembly CuO surface decorated with NiAl2O4 for high-temperature thermochemical energy storage: Excellent performance and strong interaction mechanism

High-temperature thermochemical energy storage materials with high energy density is the key technical support for the third generation concentrated solar power plants equipped with advanced energy storage system. CuO/Cu2O redox couple is one of the most promising systems due to its low cost and high energy density, but its application is limited by poor reaction performance. Herein, the self-assembly CuO surface decorated with 15 wt% NiAl2O4 is prepared with excellent redox reversibility and ultralong lifespan. Its reaction rate is increased by 4.2 times with re-oxidation degree increasing from 46 % to 99.9 %. The thermochemical energy density of storage and release reach −772.726 kJ/kg and 764.655 kJ/kg, respectively. After 1000 cycles, the degree of reduction and oxidation reaction can keep 99.9 % and 98 %. The material characterization shows that NiAl2O4 are uniformly and firmly loaded on the surface of CuO/Cu2O, which significantly increases the sintering temperature and improves the reaction performance. DFT studies further confirm that NiAl2O4 has a high binding energy with CuO/Cu2O and can increase the formation energy of copper vacancy. The study reveals the anti-sintering modification mechanism of CuO/Cu2O by introducing NiAl2O4, which provides a solution toward sintering resistance of high-temperature thermochemical energy storage materials.

Spectroscopic Investigation of Carbon Dioxide Interactions with Transition Metal‐Oxide Nanoparticles

AbstractThe interactions of carbon dioxide (CO2) with metal oxides are a significant subject due to the numerous applications in which this reaction is involved. Although this reaction has been extensively studied by various infrared (IR) techniques, only a few (if any) have utilized in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). DRIFTS has an essential advantage over other traditional IR techniques in that it involves minimal sample preparation before analysis. In this work, CO2 adsorption on CoO, CuO, and α‐Fe2O3 nanoparticle surfaces was investigated by using DRIFTS. While the majority of species on CoO and CuO surfaces were observed as carbonate, on α‐Fe2O3 bicarbonate was more prevalent.

ZrO2-Doped Copper Oxide Long-Life Redox Material for Thermochemical Energy Storage

Thermochemical redox couples can satisfy the demand of high-temperature energy storage in the next-generation concentrated solar power plants. Copper oxide owns the advantage of high reaction temperature and high energy storage density but suffers from poor reversibility and cycling stability due to the sintering problem. In this work, copper oxide doped with zirconia is synthesized with a detailed analysis of its reaction performance and microstructure. Cu–Zr oxide shows a high reversibility of 99.7% in the first redox cycle and maintains a reoxidation capacity of 77.8% after 1000 cycles. Scanning electron microscopy (SEM) characterization reveals that ZrO2 particles can evenly adhere to the surface of CuO, thus inhibiting the growth of CuO particles. Molecular dynamics simulations of CuO and Cu–Zr systems also prove that the addition of ZrO2 increases the diffusion activation energy of atoms in CuO, which is key to the prevention of sintering and the improvement of cycling performance. This study investigates a generalizable sintering resistance mechanism and provides guidance for the performance improvement of thermochemical energy storage materials during the long-term operation.

Experimental Study of the Adsorption and Decomposition of Sarin on Dry Copper(II) Oxide.

Organophosphonates were originally developed as insecticides but were quickly identified as highly toxic acetylcholinesterase inhibitors, leading to their exploitation as chemical warfare agents (CWA). To develop next generation filtration technologies, there must be a fundamental understanding of the molecular interactions occurring with toxic chemicals, such as CWAs. In this paper, we investigate the interaction between dry CuO nanoparticles and sarin (GB), using infrared (IR) spectroscopy in an effort to build an atomic understanding. We show sarin strongly interacts with CuO and then quickly degrades, primarily through the cleavage of the P-F bond, creating a bridging species on the CuO surface with the assistance of lattice oxygen. Upon heating, the decomposition product isopropyl methyl phosphonic acid (IMPA) does not continue to decompose but desorbs from the surface. These observations are further elaborated through theoretical models of sarin on dry CuO (111).

Regulating crystal surface of Cu2O distributed in graphene film to explore supercapacitive performance in liquid or gel electrolyte

The morphologies of transition metal oxides have a decisive impact on the performance of their applications. In this work, two kinds of Cu2O nanocrystals with preferentially exposed {100} and {111} facets corresponding to Cu2O nano-cube (Cu2O NC) and Cu2O nano-octahedron (Cu2O NO) were designed. Then the different crystallographic Cu2O nanocrystals were self-assembled to be flexible self-supporting Cu2O and reduced graphene oxide films. By the comparison of the kinetic study of Cu2O nanocrystal with two different exposure facets, the nanocrystal with preferentially exposed {111} behaves a larger proportion of surface-confined charging process, indicating faster ion adsorption and transferability. The specific capacity of an electrode with different exposed facets behaves as an obvious shape-dependence in the aqueous two-electrode system. In contrast with the hydrogel electrolyte system, the shape-dependence disappeared due to the sufficient ions adsorb in the slow ion diffusion electrolyte. Based on the intrinsic crystallographic plane of the cuprite Cu2O, the charge-storage mechanism was elucidated. The so-called “crystallography-dependence” is relevant to the dangling bonds from the exposed {111} facets, which can act as active sites for electrochemical energy storage. Furthermore, the composite of Cu2O NO/rGO shows a high capacity of 737.4 F g−1. The Cu2O NO/rGO film with exposure {111} facets demonstrated preferential adsorption of electrostatic charges on the planes and showed better charge-storage capability. In other words, there is a crystallography-dependent adsorption ability during energy storage.

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu2O.

Well designed and optimized epitaxial heterostructures lie at the foundation of materials development for photovoltaic, photocatalytic, and photoelectrochemistry applications. Heterostructure materials offer tunable control over charge separation and transport at the same time preventing recombination of photogenerated excitations at the interface. Thus, it is of paramount importance that a detailed understanding is developed as the basis for further optimization strategies and design. Oxides of copper are nontoxic, low cost, abundant materials with a straightforward and stable manufacturing process. However, in individual applications, they suffer from inefficient charge transport of photogenerated carriers. Hence, in this work, we investigate the role of the interface between epitaxially aligned CuO and Cu2O to explore the potential benefits of such an architecture for more efficient electron and hole transfer. The CuO/Cu2O heterojunction nature, stability, bonding mechanism, interface dipole, electronic structure, and band bending were rationalized using hybrid density functional theory calculations. New electronic states are identified at the interface itself, which are originating neither from lattice mismatch nor strained Cu-O bonds. They form as a result of a change in coordination environment of CuO surface Cu2+ cations and an electron transfer across the interface Cu1+-O bond. The first process creates occupied defect-like electronic states above the valence band, while the second leaves hole states below the conduction band. These are constitutional to the interface and are highly likely to contribute to recombination effects competing with the improved charged separation from the suitable band bending and alignment and thus would limit the expected output photocurrent and photovoltage. Finally, a favorable effect of interstitial oxygen defects has been shown to allow for band gap tunability at the interface but only to the point of the integral geometrical contact limit of the heterostructure itself.

Directional growth of quasi-2D Cu2O monocrystals on rGO membranes in aqueous environments.

The preparation technology of unconventional low-dimensional Cu2O monocrystals, which exhibit specific crystal planes and present significantly unique interfacial and physicochemical properties, is attracting increasing attention and interest. Herein, by integrating a high-temperature oxidation process under vacuum and a pure-water incubation process under ambient conditions, we propose the self-assembled growth and synthesis of quasi-two-dimensional Cu2O monocrystals on reduced graphene oxide (rGO) membranes. The prepared Cu2O crystals have a single (110) crystal plane, regular rectangular morphology, and potentially well conductivity. Experimental and theoretical results suggest that this assembly is attributed to the pre-nucleation clusters aggregation and directional attachment of Cu and O on the rGO membranes in aqueous environment and cation-π interactions between the (110) crystal plane of Cu2O and rGO surface. Our findings offer a potential avenue for the discovery and design of advanced low-dimensional single-crystal materials with specific interfacial properties in a pure aqueous environment.

Effects of *CO Coverage on Selective Electrocatalytic Reduction of CO2 to Ethylene over Cu2O with Undercoordinated Cu Sites

Cu2O surface with the coordinatively unsaturated Cu sites reveals advantages in the electroreduction of CO2 toward C2H4 production. Understanding the role of *CO coverage and veritable active sites is of great significance for a good command of the catalytic mechanism. Herein, based on density functional theory, the effects of *CO coverage during the reduction of CO2 to C2H4 on various active sites of Cu2O(111) surface, in terms of the adsorption and structural changes of *CO and key intermediates; the energy profiles of the C–C coupling steps; and the subsequent reaction mechanisms were investigated. Results show that CuCUS on the Cu2O(111) surface is especially reactive toward the *CO adsorption and subsequent reactions, being the preferred site owing to the unsaturated Cu atoms. The *CO coverage obviously tunes the adsorption stability of *COH and *CHO intermediates by affecting the adsorbent–adsorbent interactions. Higher coverage of *CO within 0.13–0.25 promotes the C–C coupling by lowering the energy barrier of *CH2 dimerization, favoring the C2H4 production. Due to the more facile generation of *CHO than *COH, the rate-determining step is speculated to be the C–C coupling with the highest barrier energy occurring in the *CHO pathway. Results provide a fundamental understanding of the CO2 reduction mechanism on Cu-based surfaces, favoring novel catalysts, rational design, and chemical fuel production.

CuO surface doped In2O3/CeO2 nanofibers for ppb-ppm level carbon monoxide gas detection in low-temperature

In this work, we designed and prepared CuO-loaded In2O3/CeO2 nanofiber heterojunctions, which are promising for trace CO gas detection. We characterized the materials, confirmed the morphology of the nanofibers and structure of the p-n heterojunctions, and analyzed the effect of morphology and structure on the gas sensing performance. In gas sensing tests, the sensor is found to show a low optimum operating temperature of 70 °C, with a limit of detection that reaches as low as 50 ppb. At concentrations ranging from 50 ppb to 10 ppm, the sensor shows a sensitive and linear response for CO gas. In particular, the sensor shows a response (Ra/Rg) of 11.7–10 ppm CO gas, and a response/recovery time of 125 s/12 s for 2 ppm CO gas. In addition, we tested the selectivity, humidity response and long-term stability of the gas sensors. Finally, based on the structure of the materials, we propose a mechanism for the enhanced CO gas sensing performance.

A Density Functional Theory and Microkinetic Study of Acetylene Partial Oxidation on the Perfect and Defective Cu2O (111) Surface Models.

The catalytic removal of C2H2 by Cu2O was studied by investigating the adsorption and partial oxidation mechanism of C2H2 on both perfect (stoichiometric) and CuCUS-defective Cu2O (111) surface models using density functional theory calculations. The chemisorption of C2H2 on perfect and defective surface models needs to overcome the energy barrier of 0.70 and 0.81 eV at 0 K. The direct decomposition of C2H2 on both surface models is energy demanding with the energy barrier of 1.92 and 1.62 eV for the perfect and defective surface models, respectively. The H-abstractions of the chemisorbed C2H2 by a series of radicals including H, OH, HO2, CH3, O, and O2 following the Langmuir–Hinshelwood mechanism have been compared. On the perfect Cu2O (111) surface model, the activity order of the adsorbed radicals toward H-abstraction of C2H2 is: OH > O2 > HO2 > O > CH3 > H, while on the defective Cu2O (111) surface model, the activity follows the sequence: O > OH > O2 > HO2 > H > CH3. The CuCUS defect could remarkably facilitate the H-abstraction of C2H2 by O2. The partial oxidation of C2H2 on the Cu2O (111) surface model tends to proceed with the chemisorption process and the following H-abstraction process rather than the direct decomposition process. The reaction of C2H2 H-abstraction by O2 dictates the C2H2 overall reaction rate on the perfect Cu2O (111) surface model and the chemisorption of C2H2 is the rate-determining step on the defective Cu2O (111) surface model. The results of this work could benefit the understanding of the C2H2 reaction on the Cu2O (111) surface and future heterogeneous modeling.

Adsorption and dissociation of Cl2 on CuO(111) surface with first-principles study

The first principle calculation based on density functional theory (DFT) was used to discuss the adsorption and dissociation behaviors of Cl2 on the perfect and oxygen-deficient surfaces of CuO(111) in this paper. The adsorption behavior and reaction mechanism of Cl2 directly adsorbed on two CuO(111) surfaces were analyzed by calculating the adsorption structure, energy of adsorption, charge density difference, the electron localization function and density of states (DOS) of the system. The calculations suggest that the most advantageous site for Cl2 adsorption on the perfect CuO(111) surface is the bridge site between two Cusub atoms. However, on the oxygen-deficient CuO(111) surface, two Cl atoms dissociated from the Cl2 molecule and bound to the Cu site after optimization. The calculations indicate that the existence of oxygen vacancy is highly chemically reactive when it comes to the dissociation of Cl2, which can increase the activity of CuO significantly. Our calculations of the adsorption and dissociation of Cl2 on the CuO(111) surface can offer some microscopic information for the side products of CuO and Cl2 produced by the thermolysis of copper oxychloride and the effect of side reaction on yield.

Mechanistic insights into copper oxides catalyzed bio-based furfural hydrogenation using methanol as in-situ hydrogen donor

In the present study, CuO and Cu2O were employed in H-transfer transformation of bio-based furfural (FFR) using methanol as both the solvent and an in-situ hydrogen source, to clearly elucidate the catalytic mechanism of copper oxides (CuOx, x = 0.5, 1) during the reaction. A number of characterization techniques including XPS, H2-TPD, in-situ FTIR, etc., were undertaken to track the state of copper species. Owing to the synergistic effect of in-situ generated H2, Cu0 species and CuOx derived Brønsted/Lewis acid sites, FFR could be efficiently hydrogenated into FA and subsequently deoxygenated into MF in methanol. The combined results from in-situ characterizations and experiments show that the FFR-to-FA (FA, furfuryl alcohol) and FFR-to-MF (MF, 2-methylfuran) conversions largely depended on the hydrogen production capability from methanol reforming and FFR adsorption strength over CuOx. Density functional theory (DFT) calculations demonstrated that the CuO(200) surface revealed lower free energy and energy barriers for methanol reforming and FFR transfer hydrogenation. This study provides a promising guidance for reasonably designing copper-based materials in the hydro-upgrading of bio-based unsaturated molecules into value-added chemicals in methanol without external H2 supply.

First-principles investigation of CuO decomposition and its transformation into Cu2O

This paper reports on the mechanisms of CuO decomposition and its associated phase transformation into ${\mathrm{Cu}}_{2}\mathrm{O}$, as a fundamental step of thermite materials reaction, where CuO serves as the oxidizer. The Frenkel pair defects in perfect bulk CuO show extremely high formation energy (>4 eV) indicating that its decomposition initiates at defects/interfaces/surfaces, the latter being sensitive to surface orientation. In contrast to a variety of CuO surfaces [(111), (110), ($10\overline{1}$)] exhibiting three-fold coordinated oxygen atoms, results show that oxygen vacancy formation requires higher disordered surfaces, such as the CuO(001), on which the vacancy formation activation energy is reduced to 1.31 eV. This leads to the exothermic formation of a chemisorbed O-O peroxy-bridge complex at the surface (\ensuremath{-}1.25 eV adsorption) that thermodynamically moderates the backreaction (vacancy annihilation). Further desorption of molecular oxygen necessitates an activation of 1.53 eV, compatible with CuO decomposition observed experimentally at 600 K (\ensuremath{\sim}second process duration). As a driving mechanism of oxygen release upon decomposition, migrations of the vacancy close to the surface and towards the bulk are determined for a number of crystalline directions and surface orientations and show considerable anisotropy, with two preferential directions: [110] and [001] with 1.35 and 1.77 eV activation, lowered to 1.08 and 1.03 eV activation when approaching the (111) and (001) surfaces, respectively. Finally, the CuO to ${\mathrm{Cu}}_{2}\mathrm{O}$ phase transformation follows a two-step process: a first structural modification from monoclinic to orthorhombic takes place when CuO has lost 12.5% of its oxygen atoms, followed by a barrierless transition to the cubic phase when 44--48% of the oxygen atoms have been removed, i.e., very close to stoichiometric ${\mathrm{Cu}}_{2}\mathrm{O}$.

Atomic View on the (111) Surface of a Cu2O Single Crystal: Reconstruction, Electronic Properties, and Band-Bending Effects

The nature of the (√3 × √3)R30° reconstruction of the Cu2O(111) surface has been heavily debated for almost 30 years. This work demonstrates that the nanopyramidal reconstruction model that was recently developed for Cu2O(111) thin films is valid also for bulk samples. For this purpose, the surface of a natural Cu2O(111) crystal was prepared by common surface science methods, yielding a robust and reproducible (√3 × √3)R30° superstructure pattern in electron diffraction. Atomically resolved STM images display a regular array of trifold symmetric protrusions, in perfect agreement with the nanopyramidal model in which Cu4O units attach to every third Cu–O six-membered ring of a Cu-depleted (111) surface. STM conductance spectra reveal the p-type character of the oxide with the valence-band top pinned to the Fermi level. From band-bending effects in the tip electric field, an induced carrier concentration of 6 × 1017 cm–3 is determined for the (√3 × √3)R30° phase. This value increases to 4 × 1018 cm–3 on the few (1 × 1) patches covered with a Cu-poor minority phase, indicating a close interplay between atomic structure and local screening response for a given surface termination. Our work clarifies the nature of the (√3 × √3)R30° reconstruction of bulk Cu2O(111) by connecting it to the recently proposed nanopyramidal reconstruction model.

Microscopic insight into catalytic HCN removal over the CuO surface in chemical looping combustion

Hydrogen cyanide (HCN) is well-accepted as a main nitrogen-containing precursor from fuel nitrogen to nitrogen oxides. When using coal as fuel with a CuO-based oxygen carrier in chemical looping combustion (CLC), complex heterogeneous reactions exist among the system of HCN, O2, NO, H2O, and CuO particles. This work performs density functional theory (DFT) calculations to systematically probe the microscopic HCN heterogeneous reactions over the CuO particle surface. The results indicate that HCN is chemisorbed on the CuO surface, and the third dissociation step within the consecutive three-step HCN dissociations (HCN*→CN*→NCO*→N*) is the rate-determining step. Namely, the CN*/NCO* radicals can be deemed as an indicator of the performance of HCN removal due to their quite higher dissociation energies. With the existence of O2, H2O, and NO, the reaction mechanism of HCN conversion becomes extremely complex. Both DFT calculations and kinetic analyses determine that O2, NO, and H2O all significantly accelerate the consumption of CN*/NCO* radicals to produce various N-containing species (NOx or NH3) to different extents. Finally, a skeletal reaction network in a system of O2/NO/H2O/HCN is concluded, which clearly elucidates that CuO exhibits excellent catalytic activity toward HCN removal.

Solar light photocatalytic activity of CuO/TiO2 mixed oxide derived from conjugated azomethine metal complex for degradation of food colorants

This work illustrates the preparation of an effective photocatalyst, CuO/TiO2 nano metal mixed oxide (NMMO). The desired synthesis was carried out by calcination assisted reaction of Cu[DBAPD]/TiO2 at 650 °C. Additionally, the prepared nano metal mixed oxide material has also been confirmed by numerous characterization techniques such as XRD, FTIR, HRTEM, FESEM with EDS, XPS, BET, ESR and Photoluminescence which revealed the occurence of strong interfacial interactions between CuO and TiO2. The optical properties of the prepared NMMO have also been measured by UV–vis. spectroscopy. The prepared NMMO exhibited excellent photo-response for the total degradation of amaranth (99.21 %) as well as brilliant blue (99.68 %) after just 40 min during intense solar irradiation. It has been found that the photocatalytic degradation mechanism over the surface of CuO and TiO2 can be well explained by considering the charge flow from TiO2 to CuO. Such type of structure offered higher redox capability as well as improved separation of photogenerated charge carriers, thus providing phenomenal photocatalytic performance. In addition to this, the degradation process has been investigated utilizng mass spectrometry and UV–vis. spectral analysis. Moreover, the CuO/TiO2-NMMO photocatalytic material offered good stability and reusability and can therefore act as a strong contender to be use in environmental remediation.

Surface etching and photodeposition nanostructures core-shell Cu2O@CuO-Ag with S-scheme heterojunction for high efficiency photocatalysis

Cu2O is one of ideal candidate photocatalyst, and it has attracted considerable attention owing to its low-cost and visible light responsive. Here, a core-shell structure of Cu2O@CuO-Ag with S-scheme heterojunction was delicately designed and synthesized for efficient photocatalytic degradation of the methyl orange (MO) and reduction of Cr(VI) under visible light. The shell of CuO and Ag nanoparticles were successfully close wrapped cube Cu2O core by the in situ topotactic oxidation of Cu+ in the surface of Cu2O and light deposition strategies, respectively. The Cu2O@CuO-Ag hybrid exhibits excellent photodegradation of MO activity and the reaction constant k is approximately 0.16 min−1, that is 8.20 times and 2.18 times higher than that for pure Cu2O and Cu2O@CuO, respectively. The Cu2O@CuO-Ag hybrid was also used to remove Cr(VI), and it exhibited not only strong adsorption ability, but also displayed remarkably promote photocatalytic performance in the absence of the sacrificial agents. The origin of the efficient activity of Cu2O@CuO-Ag hybrid photocatalyst was synergistic reaction to promote charge separation by S-scheme heterojunction designing and Ag acted as electron trap. This work provides a reference to design heterojunction photocatalysts based on Cu2O for photodegradation.

Oxidation of Cu3N thin films obtained from Cu annealed under NH3:O2 flow: A Raman and N-K-edge NEXAFS study

Cu3N layers prepared by annealing, under NH3:O2 flow, of Cu sputtered on Si, fused SiO2, and soda-lime-glass were studied by Raman and N-K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The annealing temperatures were ranging from 300° to 800°C. Benefiting from resonance effects on the Raman peak intensities when different excitation wavelengths are used, the contribution in the Raman signal of copper oxides, which provide peaks lying close to those of Cu3N, is more easily discriminated. The formation of Cu2O surface oxide is observed in almost all the samples even for annealing at low temperatures. CuO is generally formed at higher temperatures with the onset depending on the amount of O2 in the NH3:O2 mixture. However, high temperature is necessary to grow larger crystallites, as it is deduced from the decrease in the width of the high-frequency Raman peak (at ca. 650 cm−1) of Cu3N, in accordance with Scanning Electron Microscopy observations. The formation of CuO is accompanied by the creation of N2 trapped in the sample, which is directly detected by the NEXAFS measurements. N2 is most probably formed by the N atoms originating from the dissociation of the Cu-N bonds.

Resistive Hydrogen Sensor Based on Amorphous CuO Thin Film Covered With Pd Nanoparticles

The sputtered copper oxide (CuO) film covered with palladium (Pd) nanoparticles (NPs) is employed to fabricate a high-performance p-type resistive hydrogen sensor. The metal NPs on the top layer of the sensor could accelerate the catalysis and expand the sensing surface area. When hydrogen is sensed at high temperature, the reaction between hydrogen molecules and oxygen ions on the surface of CuO thin film will form free electrons, which free electrons will release back to the conduction band of p-type CuO thin film. These holes recombined with the released free electrons on the CuO surface results in an increase of the surface-depletion depth of CuO thin film. This gives the reduction (increase) in the hole concentration (resistance) of p-type CuO. In addition, the sensing response ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S_R</i> ) rises to the highest when the operation temperature reaches 300 °C. It exhibits a high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S_R</i> of 13.22 at 1% H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /air and a low detection level of 50 ppb H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /air at 300 °C. The device takes the advantages of easy fabrication process, simple structure, high sensing response, and low cost, which provides a promise for the sensing of hydrogen at high temperature.

First-principles kinetic Monte Carlo modeling of propylene epoxidation on the Ti2CuO6/Cu(111) and Cu2O(111) surfaces

Direct propylene epoxidation by molecular oxygen is one of the most important commercial selective oxidation reactions. Although the mixed metal oxide (Ti2CuO6/Cu(111)) with highly dispersed and stabilized Cu+ has high selectivity toward propylene oxide (PO), the reaction mechanism and the physical nature of stable Cu+ involved in Ti2CuO6/Cu(111) remain unclear. To better understand the key role of stabilized Cu+ active sites, the systematic kinetic Monte Carlo (kMC) studies of the propylene epoxidation reaction on Ti2CuO6/Cu(111) and Cu2O(111) surfaces are carried out. It was found that O2 is weakly bound to Ti2CuO6/Cu(111) due to the less active of Cu+ ions compared to that of Cu+ ions in Cu2O(111), which can exist stably. The current simulation demonstrates that the relatively stable Ti2CuO6/Cu(111) mixed oxide exhibits better PO selectivity and activity than Cu2O(111). The reasons for the different catalytic performance are revealed: For the primary chemistry of propylene epoxidation mechanism, Cu2O(111) favors the first allylic hydrogen stripping, while Ti2CuO6/Cu(111) has an excellent open-shell electronic structure character, which makes it more reactive toward the propylene double bond to form the oxametallacycle (OOMMP or OMMP). For the secondary chemistry of propylene epoxidation mechanism, the energy barrier of PO formation is smaller than that of propanal(PA)/acetone(AC) due to the larger difference in bonding affinity toward the O and C atoms. In contrast, the opposite trend holds for Cu2O(111). In addition, the surface species can be balanced quickly on Ti2CuO6/Cu(111). The catalyst surface is not poisoned because the surface species coverage is moderate, which means that Ti2CuO6/Cu(111) remains highly stable during the reaction processes. The Cu2O(111) has fewer active sites due to higher surface species coverage (i.e., catalyst poisoning). One may rationally design an efficient propylene epoxidation catalyst based on the present work, i.e., doping Cu into the stable spinels or perovskites such as Cu-modified LaCoO3 perovskites (LaCoxCu1−xO3−δ) may show the similar catalytic properties like that of Ti2CuO6/Cu(111).