Effect of the titania morphology on the Au/TiO2-catalyzed aerobic epoxidation of stilbene

We use a colloidal deposition method to prepare gold nanoparticles with similar size distributions centered at 3 nm over various anatase titania supports. All UV100, PC500 and AK350 titanias are loaded with similar amount of gold (1.0 ± 0.2 wt.%) which is in similar electronic and optical environments, as shown by X-ray photoelectron spectroscopy (XPS) and UV–vis. This allows us to assess the effect of the titania crystallization, morphology and chemical composition on the catalytic properties of gold in the aerobic epoxidation of trans-stilbene. We find that Au/UV100 is more active than Au/PC500 and Au/AK350 but that selectivities are similar on all materials. Epoxide yields on the other hand critically depend on the support functionalization and surface composition. TG–DTA characterization of the bare titania powders reveals indeed that AK350, which leads to the least active catalyst, is slightly less hydroxylated than PC500 and UV100. This indicates that surface titanol groups might be involved in the epoxidation of trans-stilbene. The presence of boron oxide on Au/UV100 (XPS), due to reaction of UV100 with the NaBH₄ reductant during the synthesis, is also thought to promote the epoxide-forming mechanism. This chemical promotion effect appears to compensate for the specific and beneficial gold–P25 interaction. As a result, Au/UV100 is more efficient than the reference Au/P25 catalyst for this reaction.     

NO2 gas sensing properties of Au-functionalized porous ZnO nanosheets enhanced by UV irradiation

Porous ZnO nanosheets were synthesized by thermal evaporation. The morphology, crystal structure, and sensing properties of the ZnO nanosheets to NO₂ gas at room temperature under UV illumination were examined. Au nanoparticles with diameters of a few tens of nanometers were distributed over the ZnO nanosheets. The responses of the multiple networked nanosheet gas sensors were improved 1.8–3.3 fold by Au functionalization at NO₂ concentrations ranging from 1 to 5 ppm. Furthermore, the Au-functionalized ZnO nanosheet gas sensors showed a considerably enhanced response at room temperature under ultraviolet (UV) illumination. In addition, the mechanisms through which the gas sensing properties of ZnO nanosheets are enhanced by Au functionalization and UV irradiation are discussed.     

Hydroformylation of olefins by Au/Co3O4 catalysts

The hydroformylation of olefins over supported gold catalysts in an autoclave reactor under mild conditions (100–140 °C, 3–5 MPa) has been studied. Over Au/AC (activated carbon), Au/PVP (polyvinylpyrrolidone), Au/Al₂O₃, Au/TiO₂, Au/Fe₂O₃, Au/ZnO, Au/CeO₂ and Co₃O₄, 1-olefin mainly remained unchanged and the major products were isomerized olefins or hydrogenated paraffin. In contrast, Au nanoparticles deposited on Co₃O₄ led to remarkably high catalytic activities in hydroformylation reaction with selectivities above 85% to desired aldehydes. The hydroformylation of olefins proceeds preferentially at temperatures below 140 °C, above which the reactions of olefins gradually shifted to isomerization and then to hydrogenation. It appeared that the activity and selectivity of hydroformylation reaction strongly depend on the molecular structure of olefins, which could be ascribed to steric constraints as internal olefins are relatively inappropriate to form alkyl group and subsequent acyl group by insertion of CO. The Au/Co₃O₄ catalyst can be recycled by simple decantation with slight decrease in catalytic activity along with an increase in recycle times, which is a great advantage over homogeneous catalysts. The role of gold nanoparticles can be assumed to dissociate hydrogen molecule into atomic species which reduce Co₃O₄ to Co metal under mild reaction conditions.     

Facile synthesis and superior ethyl acetate sensing performance of Au decorated ZnO flower-like architectures

Au decorated ZnO flower-like architectures assembled from single crystal nanowires have been successfully synthesized. A facile thermal treatment route was employed, utilizing the composite gel of zinc acetate and polyvinyl pyrrolidone (PVP) as raw materials and was followed by a subsequent Au reduction process. PVP served as a surfactant and played a critical role in the generation of crystalline nanowires as well as for the formation of ZnO flower-like structure. Based on control experiments, the growth mechanism of ZnO flower-like structures was proposed. The diameter of ZnO crystalline nanowires was approximately 50–80 nm and the size of Au particles deposited on the surface of ZnO nanowires was approximately 5 nm. When tested as gas sensing material, the as-prepared Au decorated ZnO flower-like architecture exhibited superior gas sensing performance compared to ethyl acetate in terms of high response (approximately 102 at 100 ppm), short response and recovery times (10 s and 13 s, respectively), and low operating temperature (240 °C). The superior gas sensing performances are mainly attributed to the synergistic effects of ZnO crystalline nanowires and Au nanoparticles, as well as to the flower-like structure.     

Au–Pt nanoparticles in amine functionalized MCM-41: Catalytic evaluation in hydrogenation reactions

Nano-sized Au–Pt nanoparticles (Au–Pt-bi-MNPs) have been synthesized by the simultaneous reduction of HAuCl₄ and HPtCl₆ by NaBH₄ inside the channels of amine functionalized Si-MCM-41 (NH₂–Si-MCM-41) at ambient conditions. These materials were characterized using chemical analysis, UV–vis, XPS, XRD, FT-IR, Surface area and TEM analysis. The size of these alloyed nanoparticles (bi-MNPs) were found in the range of 2–4 nm. These nanoparticles were evaluated to study their catalytic activities towards hydrogenation of aromatic nitro compounds. The catalytic activity of the Au–Pt bi-MNPs was found to be superior to monometallic Au nanoparticles.     

Preferential Oxidation of CO in H2-Rich Gas at Low Temperatures over Au Nanoparticles Supported on Metal Oxides

We investigated Au catalysts supported on TiO₂, Fe₂O₃, and ZnO for their preferential oxidation of CO in a H₂-rich atmosphere. Both full conversion and selectivity were achieved over Au/Fe₂O₃ and Au/ZnO around room temperature, but at higher temperatures the CO conversion was suppressed due to competition between CO and H₂.     

Ir promotion of TiO2 supported Au catalysts for selective hydrogenation of cinnamaldehyde

We synthesized Ir-on-Au (Au–Ir) nanoparticles (NPs) using 8–9 nm Au NPs, which had a partial coverage of Ir. Both the studied systems allowed the obtainment of cinnamyl alcohol with high selectivities (> 83%). However, Au–Ir/TiO₂ delivered a hydrogenation rate 5 times higher than that of Au/TiO₂. The deposition of Ir onto the surface of Au and the presence of surface Au–Ir alloy were confirmed by UV–vis and HRTEM respectively. Moreover. Moreover, the strongly shifted XPS binding energy implyed the electron transfer from Ir to Au, which was believed to be responsible for the enhanced H₂ activation capacity of Au.     

Synthesis and stabilization of Au nanoparticles in colloidal solution using macroelectrolytes with sulfonic acid groups

Metal nanoparticles are obtained by different chemical reactions using reducing agents that are not environmentally friendly. This work report the synthesis of Au nanoparticles in colloidal solution using three monodisperse macroelectrolytes, with peripheral sulfonic acid groups bonded covalently, without toxic reducing agents. During the synthesis of Au nanoparticles were used the new macroelectrolytes as reducing and stabilizing agents in aqueous solution or ethylene glycol. The macroelectrolytes were synthesized using hexachlorocyclotriphosphazene as core, and o‐ or p‐aminobenzenesulfonic acid, obtaining acid macroelectrolytes with two and six sulfonic acid groups in ortho‐ position, and four sulfonic acid groups in para‐ position. The ultraviolet–visible (UV–vis) absorption spectroscopy and transmission electron microscopy study show that the macroelectrolytes with sulfonic acid groups in ortho‐ position are reducing agents for Au⁺⁺⁺ ions in colloidal solution and produced Au nanoparticles with anisotropic shapes, such as decahedrons and prisms. The macroelectrolyte with sulfonic acid groups in para‐ position is reducing agent for Au⁺⁺⁺ and produces quasispherical Au nanoparticles with sizes between 8 and 40 nm. The colloidal solutions with Au nanoparticles were stable by several months due to the protection of imine and sulfonic groups of macroelectrolytes on the Au nanoparticles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45888.     

Biosynthesized Ag–ZnO nanohybrids exhibit strong antibacterial activity by inducing oxidative stress

We report facile biosynthesis of Ag–ZnO nanohybrids consisting of Ag nanoparticles decorated ZnO nanobullets prepared by decorating wet chemically synthesized ZnO nanobullets with Ag nanoparticles through bioreduction of Ag ⁺ ions with aqueous extract of Piper nigrum fruits. The prepared nanomaterials were well characterized by FESEM, TEM, HRTEM, EDX, XRD, XPS, PL and UV–vis spectroscopy. FESEM and TEM analyses on the nanohybrids revealed ∼18 nm Ag nanoparticles decorating ZnO nanobullets with average size ∼48 nm. XRD results revealed hexagonal wurtzite ZnO with 22.4 nm crystallite size and FCC Ag with 18.7 nm crystalline size. Ag–ZnO nanohybrids exhibited strong antibacterial action against Escherichia coli, Bacillus oceanisediminis and Pseudomonas entomophila and efficiently inhibited their growth at 100 μg/mL, 50 μg/mL and 125 μg/mL, respectively. The molecular basis of antibacterial action of Ag–ZnO nanohybrids against E. coli was investigated using different biochemical and molecular assays. Addition of antioxidant histidine suppressed the antibacterial action of Ag–ZnO nanohybrids towards E. coli due to its ROS scavenging action. Bradford assay results showed enhanced protein leakage from Ag–ZnO nanohybrids treated E. coli, while TBARS assay results confirmed lipid peroxidation triggered by ROS. SEM on Ag–ZnO nanohybrids treated E. coli confirmed significant damage to the cell wall leading to morphology change. The antibacterial activity of Ag–ZnO nanohybrids against E. coli is mainly due to the ROS-induced oxidative stress, which caused enhanced lipid peroxidation, cell wall damage leading to significant protein leakage and DNA fragmentation.     

Adsorption and decomposition of ethanol on supported Au catalysts

The adsorption and reactions of ethanol are investigated on Au nanoparticles supported by various oxides and carbon Norit. The catalysts are characterized by means of XPS. Infrared spectroscopic studies reveal the dissociation of ethanol to ethoxy species at 300 K on all the oxidic supports. The role of Au is manifested in the enhanced formation of ethoxy species on Au/SiO₂, and in increased amounts of desorbed products in the TPD spectra. The supported Au particles mainly catalyse the dehydrogenation of ethanol, to produce hydrogen and acetaldehyde. An exception is Au/Al₂O₃, where the main process is dehydration to yield ethylene and dimethyl ether. C–C bond cleavage occurs to only a limited extent on all samples. As regards to the production of hydrogen, the most effective catalyst is Au/CeO₂, followed by Au/SiO₂, Au/Norit, Au/TiO₂ and Au/MgO. A fraction of acetaldehyde formed in the primary process on Au/CeO₂ is converted above 623 K into 2-pentanone and 3-penten-2-one. The decomposition of ethanol on Au/CeO₂ follows first-order kinetics. The activation energy of this process is 57.0 kJ/mol. No deactivation of Au/CeO₂ is observed during 10 h at 623 K. It is assumed that the interface between Au and partially reduced CeO₂ is responsible for the high activity of the Au/CeO₂ catalyst.     

Green Synthesis of Zinc Oxide Nanoparticles (ZnO NPs) for Effective Degradation of Dye,Polyethylene and Antibacterial Performance in Waste Water Treatment

At present, there is a vital need for river water purification by developing new approaches to eliminate bacterial biofilms, textile dyes, and Low-Density Polyethylene (LDPE) plastics that pose severe threats to human and environmental health. The current work put forward the construction of an eco-friendly green strategy to synthesize zinc oxide nanoparticles (ZnO NPs) using areca nut (Areca catechu) extract and their application to tackle the challenges in water purification. Prepared biogenic NPs were characterized by X-ray diffraction analysis (XRD), Fourier Transform Infra-Red (FT-IR), Energy Diffraction Spectroscopy (EDS), Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM) analysis, confirmed the spherical shape in 20 nm and UV–vis spectroscopy. The characteristic absorption band exhibited at 326 nm confirmed the formation of ZnO NPs using UV–vis spectroscopy. Among all the tested bacterial pathogens, the E. coli at 50 µg/mL concentration showed the highest inhibition of biofilm activity, followed by the highest growth curve, cellular leakage, and potassium ion efflux. The ZnO NPs observed with photo-degradation of Rhodamine-B (Rh-B), Methylene Blue (MB), and Nigrosine dyes under sunlight irradiation at different time intervals. Finally, the photocatalytic activity of LDPE-ZnO NPs nanocomposite film showed the highest degradation under solar light irradiation were confirmed through photo-induced weight loss, SEM, FTIR, and MALDI-TOF analysis. This study demonstrates ZnO NPs exhibit efficacy against biofilm formation, degradation of photocatalytic textile dyes, and low-density LDPE film under solar light irradiation, which can be a step forward in water purification.

     

Highly Efficient and Recyclable Au/Aniline-Pentamer-Based Electroactive Polyurea Catalyst for the Reduction of 4-Nitrophenol

Heterogeneous catalysts based on metallic nanoparticles are promising candidates for wastewater treatment. However, they aggregate easily as a result of their high surface energy. Polymers are very popular supporting catalyst materials because they can stabilize the metallic nanoparticles to prevent aggregation. In this study, aniline-pentamer-based electroactive polyurea (EPU) was synthesized by oxidative coupling, and Au nanoparticles were anchored to the EPU via its aniline segments. Electrochemical redox behavior of the as-synthesized EPU was monitored by electrochemical cyclic voltammetry. The Au/EPU composite was characterized by FTIR, UV–vis, TGA, SEM, TEM, XRD XPS, and ICP-OES. SEM showed that the EPU had a flower-like structure, and the Au nanoparticles were uniformly immobilized on the EPU surface. The reduction of 4-nitrophenol (4-NP) by NaBH₄ was used as a model reaction to evaluate the catalytic properties of the Au/EPU composite. Moreover, the optimization of the reaction conditions for the reduction of 4-NP to 4-aminophenol (4-AP) were also studied in detail. The Au/EPU composite catalyzed the reduction of 4-NP to 4-AP within 4 min with a rate constant of 2.4?×?10^–2 s^?1 and an activation energy of 40.17 kJ/mol. The Au/EPU composite demonstrated high conversion (98%) after 20 successive cycles.

Graphical abstract

     

Enhanced photocatalytic degradation of Acid Blue 1 using Ni-Decorated ZnO NPs synthesized by sol-gel method: RSM optimization approach

In this research, the synthesis of pure and Ni-decorated ZnO nanoparticles was carried out successfully by sol-gel method. The morphology, structure, chemical bonding, and absorption spectrum of the synthesized nanoparticles were investigated using FESEM, TEM, XRD, EDX and elemental mapping, FT-IR, and UV–Vis techniques. After Ni decoration, the spherical structure of ZnO nanoparticles almost changed to uniform hexagonal nanoparticles. The synthesized nanoparticles were used for Acid Blue 1 dye degradation through a photocatalysis procedure under UV light (6 w). The influence of four factors, including metal (Ni) percentage, dye concentration, catalyst dosage, and pH, on the photocatalytic activity of the synthesized photocatalysts, was studied. The experiments were evaluated by means of the response surface methodology (RSM) based on the central composite design (CCD). The experimental results indicated dye concentration = 10 mg/L, pH = 7.77, Ni percentage = 1.117% and catalyst dosage = 1.07 g/L as the optimum values for variables. At optimum conditions, CCD estimated the degradation rate equal to 90.23% which is close to the experimental efficiency, 89.13%, (R² = 0.9877 and adjusted R² = 0.9762). The results confirmed the reliability of the CCD to predict the amount of dye removal. Additionally, the Ni-decorated ZnO nanoparticles had more activity in the visible area than the pure ZnO sample. According to the UV–Vis spectra, the band gap decreased from 3.13 to 2.97 eV by adding Ni to ZnO. Furthermore, the Ni-decorated ZnO sample represented a significant redshift compared to the pure sample.     

Site-specific growth of Au particles on ZnO nanopyramids under ultraviolet illumination

In this work, wurtzite ZnO nanocrystals with unique "pyramid" morphology were firstly prepared via solvothermal synthesis. It was determined that the ZnO nanopyramids are grown along the polar c-axis with the vertexes pointing to the [001] direction. When the mixture of ZnO nanopyramids and Au precursor (HAuCl(4)) was exposed to ultraviolet (UV) illumination, Au particles were site-specifically formed on the vertexes of ZnO nanopyramids. The obtained Au/ZnO nanocomposite showed significantly enhanced photocatalytic activity as compared to the bare ZnO nanopyramids. First-principles based calculations well explained the formation of ZnO nanopyramids as well as the site-specific growth of Au, and revealed that during the photocatalysis process the Au particles can accommodate photoelectrons and thus facilitate the charge separation.     

Preparation and characterization of TiO2 photocatalysts by Fe doping together with Au deposition for the degradation of organic pollutants

Fe³⁺ doped TiO₂ deposited with Au (Au/Fe–TiO₂) was successfully prepared with an attempt to extend light absorption of TiO₂ into the visible region and reduce the rapid recombination of electrons and holes. The samples were characterized by X-ray diffraction (XRD), N₂ physical adsorption, Raman spectroscopy, atomic absorption flame emission spectroscopy (AAS), UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The photocatalytic activities of the samples were evaluated for the degradation of 2,4-chlorophenol in aqueous solutions under visible light (λ > 420 nm) and UV light irradiation. The results of XRD, XPS and high-resolution transmission electron microscopy (HRTEM) analysis indicated that Fe³⁺ substituted for Ti⁴⁺ in the lattice of TiO₂, Au existed as Au⁰ on the surface of the photocatalyst and the mean particle size of Au was 8 nm. Diffuse reflectance measurements showed an extension of light absorption into the visible region for Au/Fe–TiO₂, and PL analysis indicated that the electron–hole recombination rate has been effectively inhibited when Au deposited on the surface of Fe-doped TiO₂. Compared with Fe doped TiO₂ sample and Au deposited TiO₂ sample, the Au/Fe–TiO₂ photocatalyst exhibited excellent visible light and UV light activity and the synergistic effects of Fe³⁺ and Au was responsible for improving the photocatalytic activity.     

Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm^-2 at 0.3 V) than the commercial Pd black (0.85 mA cm^-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.     

Barrier,rheological, and antimicrobial properties of sustainable nanocomposites based on gellan gum/polyacrylamide/zinc oxide

In this study, we used a solution casting method to prepare gellan gum (G)-based ternary nanocomposite films containing polyacrylamide (P) and zinc oxide (ZnO) nanoparticles. All composites were prepared using the chemical cross-linker N,N-methylenebisacrylamide. The nanocomposites were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and scanning electron microscopy. Attenuated total reflectance FTIR revealed strong hydrogen bonding interactions among gellan gum, polyacrylamide, and ZnO, which enhanced the physiochemical, thermal, and mechanical properties of the GPZnO nanocomposites. The addition of ZnO nanoparticles increased the glass transition temperature (T_g: 181.8–196.3°C), thermal stability (T_5%: 87.8–96.5°C), and char yield (23.9–29.1%) of the GP composite films, as well as their the tensile strength (from 33.5 to 43.8 MPa) and ultraviolet (UV) blocking properties (~99.2% protection against UVB [280–320 nm]). ZnO significantly influenced the rheological properties of the GP composite. The prepared GP and GPZnO nanocomposites exhibited shear thinning behavior and their viscosities decreased when there is an increase in shear rate. Storage and loss modulus increased with frequency with the addition of ZnO nanoparticles. The GPZnO films exhibited reduced hydrophilicity, moisture content, and water barrier properties compared with the GP film. The GPZnO nanocomposites exhibited effective antimicrobial activity against six different pathogens. The prepared GPZnO films could be useful in biodegradable packaging applications.     

Reactivity and sintering kinetics of Au/TiO2(110) model catalysts: particle size effects

We review here our studies of the reactivity and sintering kinetics of model catalysts consisting of gold nanoparticles dispersed on TiO₂(110). First, the nucleation and growth of vapor-deposited gold on this surface was experimentally examined using x-ray photoelectron spectroscopy and low energy ion scattering. Gold initially grows as two-dimensional islands up to a critical coverage, θ _cr, after which 3D gold nanoparticles grow. The results at different temperatures are fitted well with a kinetic model, which includes various energetic parameters for Au adatom migration. Oxygen was dosed onto the resulting gold nanoparticles using a hot filament technique. The desorption energy of O_a was examined using temperature programmed desorption (TPD). The O_a is bonded ~40% more strongly to smaller (thinner) Au islands. Gaseous CO reacts rapidly with this O_a to make CO₂, probably via adsorbed CO. The reactivity of O_a with CO increases with increasing particle size, as expected based on Br?nsted relations. Propene adsorption leads to TPD peaks for three different molecularly adsorbed states on Au/TiO₂(110), corresponding to propene adsorbed on gold islands, to Ti sites on the substrate, and to the perimeter of gold islands, with adsorption energies of 40, 52 and 73 kJ/mol, respectively. Thermal sintering of the gold nanoparticles was explored using temperature-programmed low-energy ion scattering. These sintering rates for a range of Au loadings at temperatures from 200 to 700 K were well fitted by a theoretical model which takes into consideration the dramatic effect of particle size on metal chemical potential using a modified bond additivity model. When extrapolated to simulate isothermal sintering at 700 K for 1 year, the resulting particle size distribution becomes very narrow. These results question claims that the shape of particle size distributions reveal their sintering mechanisms. They also suggest why the growth of colloidal nanoparticles in liquid solutions can result in very narrow particle size distributions.     

Ultraviolet photodetectors based on ZnO nanoparticles

Ultraviolet (UV) photodetectors based on ZnO nanoparticles (NPs) were fabricated and their optoelectronic properties were examined. The dominant photoluminescence (PL) peak of the ZnO NPs was located at a wavelength of 380 nm under the illumination of 325-nm wavelength light. The direct bandgap transition of the charge carriers at λ = 380 nm contributed to the photocurrent. The ratio of the photocurrent to the dark current (on/off ratio) was as high as 10⁶, which is favorable for photodetectors. The decay time constant in the photoresponse was relatively small, while the rise time constant was relatively large. The reasons for the high on/off ratio and photoresponse characteristics are discussed in this paper.     

Au/Ce1−xZrxO2 as effective catalysts for low-temperature CO oxidation

The physico-chemical properties and activity of Ce-Zr mixed oxides, CeO₂ and ZrO₂ in CO oxidation have been studied considering both their usefulness as supports for Au nanoparticles and their contribution to the reaction. A series of Ce_1−xZr_xO₂ (x = 0, 0.25, 0.5, 0.75, 1) oxides has been prepared by sol–gel like method and tested in CO oxidation. Highly uniform, nanosized, Ce-Zr solid solutions were obtained. The activity of mixed oxides in CO oxidation was found to be dependent on Ce/Zr molar ratio and related to their reducibility and/or oxygen mobility. CeO₂ and Ce_0.75Zr_0.25O₂, characterized by the cubic crystalline phase show the highest activity in CO oxidation. It suggests that the presence of a cubic crystalline phase in Ce-Zr solid solution improves its catalytic activity in CO oxidation. The relation between the physico-chemical properties of the supports and the catalytic performance of Au/Ce_1−xZr_xO₂ catalysts in CO oxidation reaction has been investigated. Gold was deposited by the direct anionic exchange (DAE) method. The role of the support in the creation of catalytic performance of supported Au nanoparticles in CO oxidation was significant. A direct correlation between activity and catalysts reducibility was observed. Ceria, which is susceptible to the reduction at the lowest temperature, in the presence of highly dispersed Au nanoparticles, appears to be responsible for the activity of the studied catalysts. CeO₂-ZrO₂ mixed oxides are promising supports for Au nanoparticles in CO oxidation whose activity is found to be dependent on Ce/Zr molar ratio.