CuOx Species Research Articles

CuOx supported LaCoO3 perovskite for the photoassisted reverse water gas shift reaction at low temperature

CuOx/LaCoO3 systems have been studied for the rWGS reaction under thermal assisted photocatalytic conditions within low temperature range of 180–330 ºC. CuOx species deposited from chemical reduction method over LaCoO3 homogeneously covered the perovskite surface. The reduction pretreatment before reaction leads to the partial Co reduction and the complete reduction of Cu. A significant improvement on CO production has been attained upon Cu incorporation. In addition, upon UV–vis irradiation the CO production is also enhanced. Best results have been obtained for 5 wt% Cu. The highest synergistic effect was observed for the lowest temperature, for which catalytic contribution is negligible. Thus, a good compromise is attained at 300 ºC for which a CO production of 5.45 mmol/h·g and 92 % selectivity, showing a good synergistic effect between thermo and thermo-photocatalytic activity.

Improving the NH3 oxidation and removing NOx during ammonia-rich fuel catalytic combustion using the Ag/CuOx@SiO2 catalyst with high-temperature catalytic activity

Ammonia, as a carbon-free, hydrogen-rich and renewable fuel, is of great significance for building the zero-carbon emission energy supply system in the word. However, the drawbacks of high ignition energy and high NOx emissions limit its widespread application. Catalytic combustion provides a reliable option for NH3 combustion. In the study, the catalyst of Ag/CuOx@SiO2 catalyst with high-temperature catalytic activity was prepared, and the catalytic flow reactor was employed to evaluate the ability of the catalyst in enhancing NH3 oxidation and removal NOx during NH3-rich combustion with high temperature region (900 K∼1400 K) and wide equivalence ratio range (0.4 ∼ 1.2). The high-temperature catalytic activity of the catalyst was proved by XPS spectrogram that the valence states of Ag and CuOx species in the catalyst have not been changed after the catalytic combustion. The results of catalytic combustion indicated that the catalyst enhanced the NH3 oxidation significantly. Compared to NH3 combustion, the temperature of 100 %NH3 conversion (T100) was decreased by over 500 K during NH3 catalytic combustion. Moreover, catalytic combustion performed higher efficiency on enhancing NH3 oxidation than the approach of co-firing NH3 with higher reactive gas fuels. The T100 of NH3 catalytic combustion was lower by 200 K∼220 K than that of NH3/H2 and NH3/CH4 combustion. Furthermore, the catalyst reduced the NOx effectively during NH3/H2 and NH3/CH4 combustion. At 1400 K, NO selectivity during NH3/H2 and NH3/CH4 catalytic combustion reduced by 86.80 %∼90.42 % and 43.61 %∼61.42 % compared to the combustion, respectively. Additionally, the peak of N2O selectivity moved to lower temperature range during catalytic combustion. Especially in stoichiometric and fuel rich conditions, the peak temperature reduced by 100 K∼200 K. The study provided references for the development of catalysts in ammonia-rich fuel catalytic combustion.

Unraveling distinct effects between CuOx and PtCu alloy sites in Pt−Cu bimetallic catalysts for CO oxidation at different temperatures

In situ exploration of the dynamic structure evolution of catalysts plays a key role in revealing reaction mechanisms and designing efficient catalysts. In this work, PtCu/MgO catalysts, synthesized via the co-impregnation method, outperforms monometallic Pt/MgO and Cu/MgO. Utilizing quasi/in-situ characterization techniques, it is discovered that there is an obvious structural evolution over PtCu/MgO from PtxCuyOz oxide cluster to PtCu alloy with surface CuOx species under different redox and CO oxidation reaction conditions. The synergistic effect between PtCu alloy and CuOx species enables good CO oxidation activity through the regulation of CO adsorption and O2 dissociation. At low temperatures, CO oxidation is predominantly catalyzed by surface CuOx species via the Mars-van Krevelen mechanism, in which CuOx can provide abundant active oxygen species. As the reaction temperature increases, both surface CuOx species and PtCu alloy collaborate to activate gaseous oxygen, facilitating CO oxidation mainly through the Langmuir-Hinshelwood mechanism.

Sub-millisecond pulsed laser engineering of CuOx-decorated Pd nanoparticles for enhanced catalytic CO2 hydrogenation

Catalytic CO2 hydrogenation to fuels and chemicals presents a promising avenue for addressing global warming and advancing toward a net-zero economy. Surface atomic rearrangement of catalysts has attracted growing interest as a means to manipulate catalyst activity and selectivity. Herein, we designed a ternary nanocatalyst comprising CuOx species decorated Pd nanoparticles (NPs) supported on Co oxide (denoted as CPCu) for catalytic CO2 hydrogenation. Sub-millisecond laser treatment (1 mJ per pulse) was used to manipulate the surface atomic arrangements of CPCu the catalyst. The CPCu nanocatalyst showed a significant enhancement in both CH4 production and CO production at 300 °C compared to the Pd/Co catalyst. Notably, the CH4 production using the laser-treated nanocatalyst (denoted as CPCu-L) was 66.6 % higher than the untreated one (CPCu) at 300 °C. Comprehensive catalyst characterizations revealed that CuOx species promoted CO2 activation, while neighboring Pd domains effectively dissociated H2 molecules, leading to enhanced CH4 production. This study demonstrates the potential of sub-millisecond laser treatment for tailoring catalyst surfaces, offering a promising strategy to design more active and selective catalysts for CO2 hydrogenation.

Crystal growth regulation of Cu-SSZ-13 zeolites for effective catalytic reduction of NOx from automotive exhausts

In this study, glucose was used in the synthesis of SSZ-13 zeolites; it acted as a zeolite growth regulator to successfully change the morphology of SSZ-13 zeolites. The particle size of the SSZ-13 zeolites reduced from 10 to 3 μm, and the morphology of the zeolite surface changed from rough and irregular spherical to smooth and uniform cubic. The glucose-modified SSZ-13 zeolites were ion-exchanged with Cu2+ ions (named as Cu-SSZ-13-Glu) and tested for the catalytic reduction of NOx with NH3 (NH3–SCR). The results demonstrated that the catalyst Cu-SSZ-13-Glu exhibited better NH3–SCR catalytic performance than that of conventional Cu-SSZ-13, with a wider effective reaction window, superior low-temperature SCR performance, favorable anti-SO2 poisoning ability, and excellent hydrothermal stability. The characterization results of the Cu-SSZ-13-Glu sample revealed an increase in crystallinity as well as acidic sites, and an improvement in the redox properties. After hydrothermal aging, compared with traditional Cu-SSZ-13, the Cu-SSZ-13-Glu zeolites exhibited a more stable structure and maintained higher crystallinity, larger specific surface area, and microporous volume. Moreover, the Cu2+ ions in the Cu-SSZ-13-Glu zeolites were more stable, and fewer CuOx species were generated after hydrothermal aging, retaining more Cu2+ ions species and acidic sites. To summarize, the simply prepared Cu-SSZ-13-Glu zeolites exhibited excellent catalytic activity and hydrothermal stability, showing broad application prospects in the field of nitrogen oxide removal from automotive exhausts.

Mechanistic insights into the cobalt promotion on low-temperature NH3-SCR reactivity of Cu/SSZ-13

The ever-increasing demand for nitrogen oxides (NOx) emission control from diesel engines during cold start period has provided a strong impetus to improve the low-temperature NOx removal efficiency of Cu/SSZ-13 catalyst. In this work, a series of bimetallic catalysts CuCo/SSZ-13 with varying cobalt contents were prepared, and attained the significant performance enhancement in NH3 selective catalytic reduction (NH3-SCR) reaction. The promotion mechanism of these catalysts at low temperatures (< 200 °C) was proposed: (1) The introduced Co(II) ions could tune the distributions of copper species and acid sites, resulting in a higher ratio of ZCuOH/Z2Cu (Z represents a negatively charged site on zeolite framework) and much more Lewis acid sites compared with original Cu/SSZ-13. (2) The fast reaction of reactive bridging nitrates with NH3 adsorbed on Lewis acid sites via Langmuir-Hinshelwood (L-H) mechanism decreased the activation energy. However, the addition of high cobalt content facilitated the formation of inactive CuOx species, which was not conducive to maintaining high-temperature (> 500 °C) activity.

A rational construction of Pt@Cu-ZSM-5@CuOx catalyst with detached multi-functional Pt and Cu sites for high-performance acetonitrile decomposition

Pt@Cu-ZSM-5@CuOx catalyst was constructed for the catalytic oxidation of acetonitrile (AN), which achieved a complete mineralization rate and more than 95 % N2 selectivity within 300–450 °C. Characterization results revealed that the satisfactory synergistic action of hydrolysis and oxidation pathways was well achieved. The NOx release from CN oxidation reaction on out-layer CuOx species and NHx species over-oxidation over Pt sites could be eliminated by NH3 from CN hydrolysis reaction on Cu ions via internal selective catalytic reduction mechanism. The deep oxidation of carbon-containing intermediates (such as CO etc.) during CN decomposition over Cu species effectively occurred over Pt site. The encapsulation of Pt inner ZSM-5 zeolite not only strengthened low-temperature mineralization rate compared to Cu/ZSM-5 sample, but also inhibited NOx release caused by over-oxidation of AN at an elevated temperature with co-impregnation of Pt species over Cu/ZSM-5. This work provided a viable strategy for designing catalysts to effective abatement of NVOCs.

Amorphous quantum dots co-catalyst: Defect level induced solar-to-hydrogen production

Photocatalytic water splitting has been regarded as the most economical means for the production of green hydrogen. However, the conversion efficiency of photocatalytic water splitting is still low. Herein, a uniform dispersion of amorphous and nanosized CuOx species is in-situ loaded on the surface of TiO2 to form am-CuOx/TiO2, representing the first-of-its-kind amorphous quantum dots as the co-catalysts for photocatalytic process. Their CuOx particles anchor on the surface of TiO2 via bondings between the surface Ti and Cu as confirmed by X-ray absorption spectroscopy measurements. Notably, ultraviolet photoelectron spectroscopy coupled with density functional theory calculations indicates that the defect energy levels of CuOx act as the collection centers of the electrons photogenerated by TiO2. Therefore, the am-CuOx/TiO2 catalyst exhibits photocatalytic H2 evolution rate of 19.14 μmol/h under LED-365 illumination with the record-breaking AQE value of 52.29 %. This work will enable the design of more efficient photocatalytic green H2 evolution.

Hydrothermal Aging Alleviates the Phosphorus Poisoning of Cu-SSZ-39 Catalysts for NH3-SCR Reaction.

As a new type of catalyst with the potential for commercial application in NOx removal from diesel engine exhausts, Cu-SSZ-39 catalysts must have excellent resistance to complex and harsh conditions. In this paper, the effects of phosphorus on Cu-SSZ-39 catalysts before and after hydrothermal aging treatment were investigated. Compared with fresh Cu-SSZ-39 catalysts, phosphorus poisoning significantly decreased the low-temperature NH3-SCR catalytic activity. However, such activity loss was alleviated by further hydrothermal aging treatment. To reveal the reason for this interesting result, a variety of characterization techniques including NMR, H2-TPR, X-ray photoelectron spectroscopy, NH3-TPD, and in situ DRIFTS measurements were employed. It was found that Cu-P species produced by phosphorus poisoning decreased the redox ability of active copper species, resulting in the observed low-temperature deactivation. After hydrothermal aging treatment, however, Cu-P species partly decomposed with the formation of active CuOx species and a release of active copper species. As a result, the low-temperature NH3-SCR catalytic activity of Cu-SSZ-39 catalysts was recovered.

Low-temperature CO oxidation on CuO-CeO2-ZrO2 catalysts prepared by a facile surfactant-assisted grinding method

A series of CuO-CexZr1-xOy mixed oxides with different Ce contents were prepared via a facile surfactant-assisted grinding method, and their catalytic activity for CO oxidation under dry or moist atmosphere were investigated. The results indicate that the catalyst with a Ce content (x) of 0.7 in CexZr1-xOy (CuCe0.7Zr0.3) exhibited the best activity under both dry and moist atmospheres, with the temperatures corresponding to CO conversion of 90 % (T90) at a space velocity of 18000 mL/(gcat·h) being 90 and 120 °C, respectively. Combing with the physicochemical properties of the catalysts obtained by multiple characterization techniques such as ICP-OES, XRD, Raman, N2 sorption, XPS, in situ DRIFTs, H2-TPR, O2-TPD and CO-TPD, the high activity of the CuCe0.7Zr0.3 catalyst can be mainly attributed to the existence of large amounts of highly dispersed CuOx species and oxygen defect sites.

The study on Cu-ZK-5 catalyst of copper content regulation and anti-propylene poisoning mechanism in NH3-SCR reaction

Cu-ZK-5 catalysts have been attempted to utilize as NH3-SCR because they have small pores and eight-membered ring structures. In this work, Cu-ZK-5 catalysts with different copper contents were investigated. It was found that the Cu7.55-ZK-5 catalyst showed excellent activity and resistance to propylene poisoning for NH3-SCR. When the copper content is too low, the number of active copper species is less, and the activity is poor. When the copper content is too high, CuOx species will be generated to destroy the structure of the molecular sieve and affect the activity, which manifested that the optimal copper loading of Cu-ZK-5 catalyst possesses more Cu2+ species improving the activity for NH3-SCR. Furthermore, the presence of propylene on Cu7.55-ZK-5 catalyst had little impact on the low-temperature catalytic performance and exhibited excellent propylene resistance at medium and high temperatures. The influence on the low-temperature catalytic performance of the Cu-ZK-5 catalyst is mainly since C3H6 has competitive adsorption with NO on the surface of Cu-ZK-5, which may be the main reason for slightly reducing the NOx conversion of Cu-ZK-5 catalyst.

Valence-mixed CuOx-nanoparticles anchored biomass-based carbon nanofiber for boosting toxic nitroarenes reduction: Synthesis, kinetics, and mechanisms

The rational modulation of metal catalysts with tailorable valence and redox properties is a promising strategy for further improving their catalytic performance. Herein, an environment-friendly grafting and thermal strategy was adopted to immobilize copper oxides nanoparticles on carbon nanofiber (CuOx/CF). Benefiting from the defect-rich surface and valence-mixed composition of the CuOx species, the optimized sample CuOx/CF-3 exhibits superb activity for the catalytic reduction of toxic nitrophenols. The complete conversion took only 1 min and an outstanding rate constant (k) of 112.7 × 10˗3 s˗1 was achieved under mild conditions (25 °C and 1 atm). Kinetic and recycle experiments demonstrated that the whole catalytic process obeys a pseudo-order kinetic, and the catalyst could maintain high conversion even after 13 successive recycles. These results demonstrate that CuOx/CF-3 is an alternative catalyst to noble metals, providing superb catalytic efficiency and stability in the reduction of toxic nitrophenols, and it can be expanded to develop other noble-metal-free catalysts for various applications.

Sequencing the CuOx active species for CO preferential oxidation at low-temperature over CeO2-CuO composite catalysts

Composites are frequently uncovered to show superior catalytic performance at mild conditions for a variety of emerging applications in energy and environment, while identity of low-temperature active species and their role remains elusive. Herein, we took CeO2-CuO as a prototypical composite to sequence the active species responsible for the superior catalytic performance of CO preferential oxidation at low-temperature. Through data analyses of structure, reducible ability, adsorption/desorption behaviors of oxygen species, and in situ spectroscopic features, highly dispersed CuOx species are experimentally identified to be the active centers that dominate the catalytic performance as represented by a redox temperature below 150 °C. The methodology of elevating the concentration of active species is further demonstrated by increasing annealing temperature as well as by tuning the dispersion of CeO2 and CuO components that controls Ce3+ content in composite. These findings may provide hints of creating highly concentrated active sites when designing advanced composites for low-temperature catalytic applications.

Sustainability in Biofuel Production Technology

It is highly desirable but quite challenging to replace precious metals with cheaper elements in the catalytic selective hydrogenation of unsaturated aldehydes. Herein, we report the preparation of a series of CuxNi3−xAlOy mixed-metal oxides (x = 0.5, 1, 2) derived from CuxNi3−xAl hydrotalcite to be used as catalysts for the promotion of the selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL). It was found that the catalyst with the Cu2Ni1AlOy stoichiometry exhibited the best performance, with 98% FAL conversion and 99% selectivity toward FOL after 1.5 h at 120 °C and under a H2 pressure of 1.6 MPa, and also good reusability. On the basis of the combined results from catalyst characterization studies using XRD, H2-TPR, TEM, XPS, and in-situ FT-IR, it was concluded that the CuOx species on the surface of the CuxNi3−xAlOy catalysts can be reduced in situ to metallic copper during reaction, and that this Cu0 species is likely the responsible for the adsorption and conversion of FAL. The addition of Ni to these mixed-metal oxides helps disperse the Cu phase and hence make it easier to reduce and activate. It may also be that NiO can promote H2 dissociation to aid with the hydrogenation catalysis. Our work advances a new strategy for the design of simple, cheap, and efficient catalysts for the hydrogenation of FAL to FOL.

The Unique CO Activation Effects for Boosting NH3 Selective Catalytic Oxidation over CuOx-CeO2.

Slip NH3 is a priority pollutant of concern to be removed in various flue gases with NOx and CO after denitrification using NH3-SCR or NH3-SNCR, and the simultaneous catalytic removal of NH3 and CO has become one of the new topics in the deep treatment of such flue gases. Synergistic catalytic oxidation of CO and NH3 appears to be a promising method but still has many challenges. Due to the competition for active oxidizing species, CO was supposed to hinder the NH3 selective catalytic oxidation (NH3-SCO). However, it is first found that CO could significantly promote NH3-SCO over the CuOx-CeO2 catalyst. The NH3 conversion rates increased linearly with CO concentrations in the range of 180-300 °C. Specifically, it accelerated by 2.8 times with 10,000 ppm CO inflow at 220 °C. Mechanism studies found that the Cu-O-Ce solid solution was more active for CO oxidation, while the CuOx species facilitated the NH3 dehydrogenation and mitigated the competition of NH3 and CO, further stabilizing the promotion effects. Gaseous CO boosted the generation of active isolated oxygen atoms (Oi) by actuating the Cu+/Cu2+ redox cycle. The enriched Oi facilitated oxidation of NH3 to NO and was conducive to the NH3-SCO via the i-SCR approach. This study tapped the potential of CO for promoting simultaneous catalytic oxidation of coexisting pollutants in the flue gas.

Unveiling Secondary-Ion-Promoted Catalytic Properties of Cu-SSZ-13 Zeolites for Selective Catalytic Reduction of NOx.

The incorporation of secondary metal ions into Cu-exchanged SSZ-13 zeolites could improve their catalytic properties in selective catalytic reduction of NOx with ammonia (NH3-SCR), but their essential roles remain unclear at the molecular level. Herein, a series of Cu-Sm-SSZ-13 zeolites have been prepared by ion-exchanging Sm ions followed by Cu ions, which exhibit superior NH3-SCR performance. The NO conversion of Cu-Sm-SSZ-13 is nearly 10% higher than that of conventional Cu-SSZ-13 (175-250 °C) after hydrothermal ageing, showing an enhanced low-temperature activity. The Sm ions are found to occupy the six-membered rings (6MRs) of SSZ-13 by X-ray diffraction Rietveld refinement and aberration-corrected scanning transmission electron microscopy. The Sm ions at 6MRs can facilitate the formation of more active [ZCu2+(OH)]+ ions at 8MRs, as revealed by temperature-programmed reduction of hydrogen. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations indicate that there exists electron transfer from Sm3+ to [ZCu2+(OH)]+ ions, which promotes the activity of [ZCu2+(OH)]+ ions by decreasing the activation energy of the formation of intermediates (NH4NO2 and H2NNO). Meanwhile, the electrostatic interaction between Sm3+ and [ZCu2+(OH)]+ results in a high-reaction energy barrier for transforming [ZCu2+(OH)]+ ions into inactive CuOx species, thus enhancing the stability of [ZCu2+(OH)]+ ions. The influence of the ion-exchanging sequence of Sm and Cu ions into SSZ-13 is further investigated by combining both experiments and theoretical calculations. This work provides a mechanistic insight of secondary ions in regulating the distribution, activity, and stability of Cu active sites, which is helpful for the design of high-performance Cu-SSZ-13 catalysts for the NH3-SCR reaction.

Hydroxyl radicals dominate reoxidation of oxide-derived Cu in electrochemical CO2 reduction

Cuδ+ sites on the surface of oxide-derived copper (OD-Cu) are of vital importance in electrochemical CO2 reduction reaction (CO2RR). However, the underlying reason for the dynamically existing Cuδ+ species, although thermodynamically unstable under reductive CO2RR conditions, remains uncovered. Here, by using electron paramagnetic resonance, we identify the highly oxidative hydroxyl radicals (OH•) formed at room temperature in HCO3- solutions. In combination with in situ Raman spectroscopy, secondary ion mass spectrometry, and isotope-labelling, we demonstrate a dynamic reduction/reoxidation behavior at the surface of OD-Cu and reveal that the fast oxygen exchange between HCO3- and H2O provides oxygen sources for the formation of OH• radicals. In addition, their continuous generations can cause spontaneous oxidation of Cu electrodes and produce surface CuOx species. Significantly, this work suggests that there is a “seesaw-effect” between the cathodic reduction and the OH•-induced reoxidation, determining the chemical state and content of Cuδ+ species in CO2RR. This insight is supposed to thrust an understanding of the crucial role of electrolytes in CO2RR.

Solid-State Construction of CuOx/Cu1.5Mn1.5O4 Nanocomposite with Abundant Surface CuOx Species and Oxygen Vacancies to Promote CO Oxidation Activity.

Carbon monoxide (CO) oxidation performance heavily depends on the surface-active species and the oxygen vacancies of nanocomposites. Herein, the CuOx/Cu1.5Mn1.5O4 were fabricated via solid-state strategy. It is manifested that the construction of CuOx/Cu1.5Mn1.5O4 nanocomposite can produce abundant surface CuOx species and a number of oxygen vacancies, resulting in substantially enhanced CO oxidation activity. The CO is completely converted to carbon dioxide (CO2) at 75 °C when CuOx/Cu1.5Mn1.5O4 nanocomposites were involved, which is higher than individual CuOx, MnOx, and Cu1.5Mn1.5O4. Density function theory (DFT) calculations suggest that CO and O2 are adsorbed on CuOx/Cu1.5Mn1.5O4 surface with relatively optimal adsorption energy, which is more beneficial for CO oxidation activity. This work presents an effective way to prepare heterogeneous metal oxides with promising application in catalysis.

Evolution behavior and active oxygen quantification of reaction mechanism on cube Cu2O for CO self-sustained catalytic combustion and chemical-looping combustion

Catalytic combustion (CC) and chemical looping combustion (CLC) are promising technologies for energy saving and emission reduction of CO2 in treatment of steelmaking off-gas. This work firstly reports and compares the evolution behavior and quantitative reaction mechanisms of cube Cu2O model catalyst for CC and CLC reactions. The Cu2O-CC exhibited the higher activity and stability than Cu2O-CLC. The typical characterization results suggested that the only surface unstable Cu2O was oxidized to CuO, and the excellent synergistic effect of metal-oxide interface (100) between Cu+/Cu2+ and active lattice oxygen species for Cu2O-CC reaction. But, for CLC reaction, Cu2O structure was collapsed, which caused the agglomeration of CuOx species and gradual decrease of reaction stability. Three different active oxygen species (surface cycle lattice oxygen, bulk lattice oxygen, and adsorbed oxygen) and the detailed reaction pathways were proposed by the in situ IR spectroscopy, isotopic (18O2) transient exchange experiments and DFT simulation. The intrinsic activity of surface cycle lattice oxygen was higher in terms of TOF (13.5 × 10−3 s−1) and facile formation of C16O18O on the cubic interface of Cu2O-CC through adsorbed CO during CC process. The contribution degrees of Mars-van-Krevelen (M-K) and Langmuir–Hinshelwood (L-H) mechanisms for CC and CLC reactions were 76.6% and 23.4% for CC, and 89.7% and 10.3% for CLC on Cu2O catalyst, respectively.

Atmosphere-Induced Transient Structural Transformations of Pd-Cu and Pt-Cu Alloy Nanocrystals.

We have investigated the transformations of colloidal Pd–Cu and Pt–Cu bimetallic alloy nanocrystals (NCs) supported on γ-Al2O3 when exposed to a sequence of oxidizing and then reducing atmospheres, in both cases at high temperature (350 °C). A combination of in situ diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption spectroscopy was employed to probe the NC surface chemistry and structural/compositional variations in response to the different test conditions. Depending on the type of noble metal in the bimetallic NCs (whether Pd or Pt), different outcomes were observed. The oxidizing treatment on Pd–Cu NCs led to the formation of a PdCuO mixed oxide and PdO along with a minor fraction of CuOx species on the support. The same treatment on Pt–Cu NCs caused a complete dealloying between Pt and Cu, forming separate Pt NCs with a minor fraction of PtO NCs and CuOx species, the latter finely dispersed on the support. The reducing treatment that followed the oxidizing treatment largely restored the Pd–Cu alloy NCs, although with a residual fraction of CuOx species remaining. Similarly, Pt–Cu NCs were partially restored but with a large fraction of CuOx species still located on the support. Our results indicate that the noble metal present in the bimetallic Cu-based alloy NCs has a strong influence on the dealloying/migrations/realloying processes occurring under typical heterogeneous catalytic reactions, elucidating the structural/compositional variations of these NCs depending on the atmospheres to which they are exposed.