Incorporation Of Copper Ions Research Articles

Catalytic and Electrochemical Study of Cu-ZSM-5/MCM-41.

Hierarchically structured micro-mesoporous ZSM-5/MCM-41 composite materials incorporating copper ions were synthesized using pre-synthesized ZSM-5 and cetyltrimethylammonium bromide (CTAB) as a template for forming the MCM-41 structure. The composites were characterized through powder X-ray diffraction, N2 adsorption-desorption, diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. X-ray diffraction confirmed well-ordered ZSM-5 and MCM-41 structures, and UV-vis DRS showed successful copper ion incorporation. N2 adsorption-desorption revealed the presence of both microporous and mesoporous structures. To evaluate their catalytic performance, Cu-incorporated ZSM-5/MCM-41 composite catalysts were assessed through the oxidation reaction of ethylbenzene using tert-butyl hydroperoxide (TBHP) as the oxidizing agent. With a 9% (w/w) Cu-ZM-5 (5 wt % copper-incorporated ZSM-5/MCM-41) catalyst and an oxidant to ethylbenzene molar ratio of 2:1 at 40 °C in the absence of a solvent for 4 h, the process yielded acetophenone (93.2%) as the major product. Additionally, these Cu-incorporated composites were examined as electrode materials for electrochemical storage. Cyclic voltammetry and galvanostatic charge-discharge studies showed that Cu-ZM-5 exhibited pseudocapacitive behavior, with a capacitance of up to 366 F g-1 at a current density of 1 A g-1, surpassing ZSM-5 and ZSM-5/MCM-41. These results highlight Cu-ZM-5's potential as an effective electrode material for electrochemical storage applications like supercapacitors.

Exceptional light harvesting in copper doped CaTiO3 nanocuboids with surface nanosteps for the photo remediation of toxic Cr(VI) ions and dyes

Addressing the rising concerns of water pollution caused by harmful inorganic and organic contaminants is very crucial and photocatalysts with exceptional light harvesting capability are a promising way to tackle these issues. This study investigates the transformation of CaTiO3 into a visible light-active photocatalyst via copper doping. Copper-doped CaTiO3 nanocuboids were synthesized via a one-step solvothermal approach, resulting in the formation of distinctive nanostep substructures on the surface. Morphological analysis revealed the successful incorporation of copper ions into the perovskite matrix, as evidenced by the transition from smooth to rough, uneven surface features. X-ray diffraction confirmed the incorporation of Cu2+ ions into the Ti4+ site, while visible range absorption indicated a reduction in the bandgap. Furthermore, doping decreased the rate of charge carrier recombination and increased their average lifetime, prolonging the duration of active species. This modification facilitating efficient absorption of visible light and increase in the charge separation, leads to enhanced photocatalytic activity. The doped catalyst exhibited exceptional performance in the remediation of hexavalent chromium ions (98.5 % Cr6+ ions reduction to Cr3+ ions in 20 min), methylene blue (99.4 % degradation within 120 min), and eosin yellow (99.8 % degradation within 80 min) pollutants. This research underscores the potential of doping as a viable strategy for tailoring photocatalytic properties and addressing water pollution challenges.

Incorporation of copper ion promoted adsorption of anionic dye (Acid Yellow 36) by acrolein-crosslinked polyethyleneimine/chitosan hydrogel: Adsorption, dynamics, and mechanisms

In this study, a novel adsorbent, A-PEI/CS-Cu2+, was developed by crosslinking polyethyleneimine/chitosan hydrogel with acrolein and loading it with copper ions. The adsorption process of A-PEI/CS-Cu2+ on the anionic dye acid yellow 36 (AY36) was investigated by kinetic, isothermal and thermodynamic modeling. It was noteworthy that A-PEI/CS-Cu2+ exhibited rapid adsorption with a 90 % removal rate achieved within just 5 min, which was much faster than the adsorption rate of A-PEI/CS without load of copper ions and showed its potential for rapid adsorption applications. The maximum adsorption capacity for AY36 could reach up to 3114 mg g−1. In addition, the high concentration of saline wastewater was found to have almost no effect on the adsorption reaction in the salt effect test experiment. In five desorption-regeneration cycle experiments, the sample exhibited good recyclability and regeneration performance. The driving force of the adsorption process mainly originated from the electrostatic interaction, hydrogen bonding, and intermolecular interaction, in which the addition of copper ions led to the enhancement of the electrostatic interaction and chelation between A-PEI/CS-Cu2+ and AY36. Overall, the findings suggest the excellent potential of A-PEI/CS-Cu2+ for rapid and efficient adsorption, as well as its suitability for practical applications in wastewater treatment.

Copper ion incorporation in α-synuclein amyloids.

Copper ion dys-homeostasis is linked to neurodegenerative diseases involving amyloid formation. Even if many amyloidogenic proteins can bind copper ions as monomers, little is known about copper interactions with the resulting amyloid fibers. Here, we investigate copper interactions with α-synuclein, the amyloid-forming protein in Parkinson's disease. Copper (Cu(II)) binds tightly to monomeric α-synuclein in vitro involving the N-terminal amine and the side chain of His50. Using purified protein and biophysical methods in vitro, we reveal that copper ions are readily incorporated into the formed amyloid fibers when present at the start of aggregation reactions, and the metal ions also bind if added to pre-formed amyloids. Efficient incorporation is observed for α-synuclein variants with perturbation of either one of the high-affinity monomer copper-binding residues (i.e., N-terminus or His50) whereas a variant with both N-terminal acetylation and His50 substituted with Ala does not incorporate any copper into the amyloids. Both the morphology of the resulting α-synuclein amyloids (amyloid fiber pitch, secondary structure, proteinase sensitivity) and the copper chemical properties (redox activity, chemical potential) are altered when copper is incorporated into amyloids. We speculate that copper chelation by α-synuclein amyloids contributes to the observed copper dys-homeostasis (e.g., reduced bioavailable levels) in Parkinson's disease patients. At the same time, amyloid-copper interactions may be protective to neuronal cells as they will shield aberrantly free copper ions from promotion of toxic reactive oxygen species.

Unveiling the potential of HKUST-1: synthesis, activation, advantages and biomedical applications.

Metal-organic frameworks (MOFs) have emerged as a unique class of nanostructured materials, resulting from the self-assembly of metal ions or clusters with organic ligands, offering a wide range of applications in fields such as drug delivery, gas catalysis, and electrochemical sensing. Among them, HKUST-1, a copper-based MOF, has gained substantial attention due to its remarkable three-dimensional porous structure. Comprising copper ions and benzene-1,3,5-tricarboxylic acid, HKUST-1 exhibits an extraordinary specific surface area and pronounced porosity, making it a promising candidate in biomedicine. Notably, the incorporation of copper ions endows HKUST-1 with noteworthy activities, including antitumor, antibacterial, and wound healing-promoting properties. In this comprehensive review, we delve into the various synthesis methods and activation pathways employed in the preparation of HKUST-1. We also explore the distinct advantages of HKUST-1 in terms of its structural properties and functionalities. Furthermore, we investigate the exciting and rapidly evolving biomedical applications of HKUST-1. From its role in tumor treatment to its antibacterial effects and its ability to promote wound healing, we showcase the multifaceted potential of HKUST-1 in addressing critical challenges in biomedicine.

Copper-doped cherry blossom carbon dots with peroxidase-like activity for antibacterial applications.

Safety concerns arising from bacteria present a significant threat to human health, underscoring the pressing need for the exploration of novel antimicrobial materials. Nanozymes, as a new type of nanoscale material, have attracted widespread attention for antibacterial applications owing to their ability to mimic the catalytic activity of natural enzymes. In this work, we have constructed copper-doped cherry blossom carbon dots (Cu-CDs) with excellent peroxidase-like (POD) activity using a one-pot hydrothermal method. The utilization of cherry blossom as a natural material precursor significantly enhances its biocompatibility. Furthermore, the incorporation of copper ions initiates Fenton-like reaction-triggered POD-like catalytic activity, effectively eradicating bacteria by converting hydrogen peroxide (H2O2) into hydroxyl radicals (·OH). The antibacterial test results demonstrate that Cu-CDs exhibit a bactericidal efficacy of over 90% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This study presents a novel environmentally friendly nanozyme material derived from natural sources, exhibiting significant antimicrobial properties and offering innovative insights for the advancement of antimicrobial materials.

Investigations of the structure and tunable magnetic properties of Cu doped cobalt chromite nanoparticles

This article reports the synthesis, microstructural, magnetic and optical properties of copper ions substituted cobalt chromite nanoparticles. We have prepared four nanosized chromite samples with a general composition of CuxCo1-xCr2O4 (x = 0.0, 0.1, 0.2 and 0.3) using conventional wet chemical co-precipitation method. The x-ray diffraction profiles verified the presence of pure spinel crystal structure of the samples. Using the Williamson-Hall (W-H) method, the average crystallite size of all the samples were calculated to be between 11 nm and 16 nm. A tensile microstrain in all the samples was noticed. Surface morphology and average particle size of doped cobalt chromite nanocrystals was examined using HRTEM images. A moderate increment in the optical band gap was detected with increasing Cu ions in cobalt chromite nanoparticles which is attributed to the nanosize effect of the samples. The presence of all five distinctive Raman active modes in the chromite samples ensured phase purity and a decrease in crystal symmetry was also observed as the amount of Cu dopants was increased. Due to low magnetic moment of Cu2+ ions when compared with Co2+ ions, incorporation of copper ions reduces the coercive field of the host chromite system. With increasing Cu percentage in chromite especially for 30 % Cu doped sample, the spin-spiral transition TS vanishes which indicates TS is affected by the dopant concentrations.

The Crystal Structure of Tyrosinase from Verrucomicrobium spinosum Reveals It to Be an Atypical Bacterial Tyrosinase.

Tyrosinases belong to the type-III copper enzyme family, which is involved in melanin production in a wide range of organisms. Despite similar overall characteristics and functions, their structures, activities, substrate specificities and regulation vary. The tyrosinase from the bacterium Verrucomicrobium spinosum (vsTyr) is produced as a pre-pro-enzyme in which a C-terminal extension serves as an inactivation domain. It does not require a caddie protein for copper ion incorporation, which makes it similar to eukaryotic tyrosinases. To gain an understanding of the catalytic machinery and regulation of vsTyr activity, we determined the structure of the catalytically active "core domain" of vsTyr by X-ray crystallography. The analysis showed that vsTyr is an atypical bacterial tyrosinase not only because it is independent of a caddie protein but also because it shows the highest structural (and sequence) similarity to plant-derived members of the type-III copper enzyme family and is more closely related to fungal tyrosinases regarding active site features. By modelling the structure of the pre-pro-enzyme using AlphaFold, we observed that Phe453, located in the C-terminal extension, is appropriately positioned to function as a "gatekeeper" residue. Our findings raise questions concerning the evolutionary origin of vsTyr.

Synthesis and characterization of novel copper-doped modified bioactive glasses as advanced blood-contacting biomaterials

Bioactive glasses (BGs) are among the most popular biomaterial categories. Due to their biocompatibility, bioactivity, antimicrobial, and angiogenesis abilities, they are increasingly utilized in a variety of tissue-engineering applications. Despite the excellent properties of BGs, their use as blood-contact biomaterials has been restricted because of their influence on the activation of the coagulation cascade. In this study, a series of modified borate-based BGs (containing B2O3, MgO, K2O, Na2O, and different concentrations of CuO) were synthesized by a melting-derived method. The synthesized BGs exhibited anticoagulant properties thanks to removing blood-clotting elements including calcium, phosphate, and silica. The results indicated that all of the BGs were in a glassy phase and did not show any significant cytotoxicity. The modified BGs showed antibacterial properties against S. aureus and P. aeruginosa bacteria. The investigation of hemocompatibility also revealed that none of the groups caused red blood cell rupture or initiated the coagulation cascade. This research demonstrated that the incorporation of copper ions into the modified BGs could dramatically improve the endothelial cell proliferation, migration, vascular endothelial growth factor secretion, tube formation, and expression of angiogenesis-related genes (vascular endothelial growth factor , KDR, hypoxia-inducible factor-1α α, and endothelial nitric oxide), resulting in the promotion of angiogenesis properties. According to the findings, it is achievable to synthesize multifunctional BGs for use in blood-contact applications by combining increased angiogenesis, anticoagulant, and antibacterial properties suitable for vascular tissue engineering applications.

Copper-containing magnetite supported on natural clay as a catalyst for heterogeneous photo-Fenton degradation of antibiotics in WWTP effluent

The use of natural clay as a support for magnetite and copper-containing magnetite was evaluated for heterogeneous Fenton/photo-Fenton degradation of trimethoprim and sulfamethoxazole. In Fenton experiments, the incorporation of copper ions on magnetite played an important role in the decomposition of hydrogen peroxide. Photo-Fenton experiments were performed under solar and UV-LED (370 nm) irradiation, with complete degradation of both antibiotics in purified water achieved under solar irradiation. Evaluation of the effects of inorganic anions and organic carbon showed that the highest •OH scavenging was due to CO32-/HCO3- and organic matter content. From a practical perspective, treatment of wastewater treatment plant effluent under solar irradiation resulted in 52% and 41% degradation of TMP and SMZ, respectively, together with 15% removal of dissolved organic carbon. The material maintained efficiency during 3 reuse cycles, showing its potential for use as a low-cost catalyst. The intermediates identified by UHPLC/MS indicated that TMP degradation involved hydroxylation, demethylation/hydroxylation, and cleavage pathways, while SMZ degradation involved hydroxylation, breaking of the sulfonamide bond, and opening of the isoxazole ring.

A facile and versatile superhydrophilic coating on biodegradable PLA stent with stepwise assembly of metal/phenolic networks for mimicking endothelium function

The achievement of the desired hemocompatibility, anti-inflammatory, and rapid endothelialization properties has significantly contributed to the success of implantable blood-contacting materials, especially vascular stents. In this study, we constructed a facile and versatile superhydrophilic coating via the stepwise deposition of metal/phenolic networks (MPNs) using a layer-by-layer assembly technique. Tannic acid and copper ions were employed for the fabrication of MPNs, and the surface roughness and the number of hydrophilic phenolic groups were gradually increased, ultimately leading to the generation of a superhydrophilic coating, where the copper ions were also effectively incorporated. Owing to the superhydrophilicity of the coating, the binding of serum adhesion proteins, such as albumin and fibrinogen, to the surface was strongly inhibited, thereby conferring a potent antithrombotic ability. In addition, a potent antioxidant and anti-inflammatory effects were achieved through the deposition of a large amount of residual phenolic hydroxyl groups on the surface. The incorporated copper ions could also mimic endothelial function through the continuously catalyzed decomposition of endogenous S-nitrothiols (RSNOs) to release nitric oxide (NO) in situ in a controlled manner. The synergistic contribution effect of NO and superhydrophilicity, further inhibited the adhesion/activation of platelets. The optimized coating significantly inhibited the adhesion and activation of platelets, selectively supported the adhesion of endothelial cells, and suppressed the proliferation of smooth muscle cells. Such superhydrophilic coating with the incorporation of copper ions adequately addressed the basic requirements of vascular stents, in terms of antithrombosis, anti-restenosis, and enhanced endothelialization in vivo, demonstrating a promising approach for the clinical application of vascular implants.

Insights into the composition-structure-property relationship in P2O5[sbnd]CaO[sbnd]Na2O[sbnd]CuO bio-relevant glasses

Copper-containing calcium phosphate glasses possessing antimicrobial properties have attracted attention for biomedical applications in tissue engineering. Yet, composition-structure-property evaluations linking structural, thermal and optical properties with the oxidation states of copper are lacking. In this work, bio-relevant P2O5CaONa2OCuO glasses were prepared by melting with increasing [CuO]/[Na2O] molar ratios (0.1–1.5), and studied by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermal/dilatometric analysis, optical transmission, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The XRD analysis confirmed the non-crystalline structure of the glasses. The FT-IR evaluation indicated that increasing the [CuO]/[Na2O] ratio significantly supports the connectivity of the glass network. The thermal characterization revealed a trend of increase in the glass transition and softening temperatures, while the coefficient of thermal expansion decreased with increasing CuO thus harmonizing with a glass strengthening. The optical evaluation showed substantially decreased transmission from the red toward the near infrared region due to d-d transitions in Cu2+ ions. A significant red shift in the glass transmission edge was also exhibited, wherein a decrease in the optical band gap energies with increasing CuO content was indicated by Tauc plot assessment. Further evaluation of the Urbach energies was performed which suggested increased structural disorder for high [CuO]/[Na2O] ratios. While XPS did not support a trend of increasing contents of non-bridging oxygens in the glasses, it indicated copper occurred most significantly as Cu+ besides Cu2+. It is supported that the decrease in optical band gaps and increase in Urbach energies follows the incorporation of copper ions rather than an increase in non-bridging oxygens. PL spectra showed features ascribed to Cu+ merely for the glass with lowest [CuO]/[Na2O] ratio, whereas an emission quenching was indicated for higher CuO content coherent with a Cu+ → Cu2+ energy transfer.

Effect of copper concentration on ethanol sensing performance of Cu-stilbite thick film sensor

The present study deals with natural stilbite zeolite commonly named as Ca-stilbite. Ion exchange process is carried out for partial exchange of calcium ions by copper ions. Ion exchanged stilbite is characterized by different spectroscopic techniques as XRD, FTIR and EDS techniques. Thick films are deposited on pre-cleaned glass substrates using screen printing technique. The sintered films are finally used for ethanol detecting. The Ca-stilbite zeolite structure is confirmed by the characterization techniques XRD and FTIR. Incorporation of copper ions in stilbite structure can be confirmed by EDS data. The Cu-stilbite films showed good ethanol detectors. The operating temperature, ethanol response, response/recovery nature are observed to be the functions of concentration of copper ions. Higher the copper concentration (0.2M) lower is the operating temperature (90°C) and higher is the ethanol sensitivity (233). It can be concluded that partial replacement of calcium by copper ions in stilbite leads to change in operating temperature and sensitivity.

Photonic NO2 Gas Sensing with Binaphthyl‐Based Dopants

AbstractA series of reactive binaphthyl‐diimine‐based dopants is prepared and investigated with respect to their potential for the chiral induction of structural coloration in nematic liquid crystal mixture E7 and the selective photonic sensing of nitrogen dioxide (NO2). Studies of the helical twisting power (HTP) in 4‐cyano‐4′‐pentylbiphenyl (5CB) reveal HTP values as high as 375 µm‐1 and the tremendous impact of structural compatibility and changes of the dihedral binaphthyl angle on the efficiency of the chiral transfer. Detailed investigation of the sensing capabilities of the systems reveals an extraordinarily high selectivity for NO2 and a response to concentrations as low as 100 ppm. The systems show a direct response to the analyte gas leading to a concentration‐dependent shift of the reflectance wavelength of up to several hundred nanometers. Incorporation of copper ions remarkably improves the sensor's properties in terms of sensitivity and selectivity, enabling the tailored tweaking of the system's properties.

Enhanced photocatalytic activity of supported Cu-doped ZnO nanostructures prepared by SILAR method

Abstract Cu-doped ZnO (CZO) nanostructures were prepared on a glass substrate using the successive ionic layer adsorption and reaction (SILAR) method. Copper (Cu) doping has been used as a key to enhance the photocatalytic activity of ZnO. X-ray diffraction (XRD) results revealed the polycrystalline nature of the nanostructures prepared with a hexagonal wurtzite structure of ZnO. The field emission scanning electron microscopy (FE-SEM) analysis showed a change of the morphology from a granular structure to a hexagonal structure and the particle size decreased with increasing copper concentration. The transmittance showed a decrease in the visible range with the increase of copper concentration and a decrease of the optical band gap values was observed. The X-ray photoemission spectroscopy (XPS) analysis indicated that copper was in a divalent state (Cu2+) which confirms the successful incorporation of copper ions into ZnO lattices. The photocatalytic activity of CZO nanostructures prepared by the SILAR method was studied for the first time. The photocatalytic study showed that an increase in copper concentration leads to an increase in degradation efficiency. CZO nanostructures showed an enhancement in degradation efficiency of about 52% compared to undoped ZnO.

Copper based macromolecular catalysts for the hydroxylation of phenols

Copper containing macromolecules, viz., Copper-meso-tetrakis-(4-carboxyphenyl)porphyrin (CuTCPP) and Copper-meso-tetra-phenylporphyrin (CuTPP) complexes were synthesized and heterogenized on the surface of aminated SBA-15 molecular sieves. The 1H NMR, mass spectral and elemental (CHN) analyses were performed to confirm the formation of these copper complexes (CuTCPP and CuTPP). The absence of 1H NMR signal, characteristic of NH bond (-2.79 ppm in TCPP and -2.74 ppm in TPP) in CuTCPP and CuTPP clearly confirms the incorporation of copper ion in to the cavities of the TCPP and TPP ligands. In addition, the decreased intensity of the soret band and the reduction of the number of Q bands also supports the formation of copper complexes. Further the homogeneous CuTCPP and CuTPP were grafted on the amino functionalized SBA-15. The grafting of copper complexes on amino functionalised SBA-15 was evident from the surface area analysis, powder XRD and N2 sorption isotherm. In the powder XRD, the shift in 2θ value compared to parent SBA-15 materials, and the broadening of the signal supports the grafting of copper complexes in to the amino functionalized SBA-15. Both homogeneous and heterogeneous copper macromolecular complexes were used as catalysts for the hydroxylation of phenolic compounds. The catalysts showed comparable conversion (72%) with the formation of ortho- and para- substituted products which have industrial importance. The hydroxylation reaction using the copper based macromolecular catalyst was found to be first order with an activation energy of 26.03 KJ/mol. Subsequently various substituted phenolic compounds, anisole and benzene also yielded the corresponding hydroxylated product with comparable conversion.

Lattice Inclusion of Copper Ions in Ammonium Perchlorate through Co-crystallization: Impact on Lattice, Physical, and Thermal Characteristics

Ammonium perchlorate (AP) is an important oxidizer extensively used in composite solid propellants. Any alterations in the lattice configuration of AP could bring in a dramatic change in its physical, thermal, and ballistic characteristics though the basic thermodynamic properties could remain unaltered. In this work, we attempt to dope AP with copper nitrate through co-crystallization and examine its impact on the lattice, physical, and thermal characteristics. The effect of copper ion on the crystal morphology, bulk density, friability, moisture content, and the decomposition behavior is compared with normal propellant-grade AP. The incorporation of copper ion into AP resulted in an increase in bulk density and aspect ratio and a marginal decrease in the average particle size. The shape factor remained intact. The presence of copper ion remarkably decreased both the low- and high-temperature decomposition and reduced the activation energy for both stages, confirming the catalytic nature of copper-doped AP.

A Novel Hybrid Organic-Inorganic Nanomaterial: preparation, Characterization and Application in Synthesis of Diverse Heterocycles

Immobilization of metal ions on the inorganic supports has found many interesting biological, industrial, and catalysis applications. In this work, a novel organic–inorganic hybrid nanomaterial (nano-Fe3O4@TiO2-Pr-2AB@Cu) using simple chemical co-precipitation method, functionalization and subsequent incorporation of copper ion was prepared. The structure of hybrid nanomaterial was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), the field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and inductively coupled plasma-optical emission spectrometry (ICP/OES). Subsequently, the catalytic properties of the prepared hybrid nanostructure were investigated in green synthesis of dihydropyridines, amidoalkylnaphthols, and chromene derivatives. The desired products were identified by FT-IR and nuclear magnetic resonance (NMR) spectroscopies. The catalyst could be recycled for seven reaction runs with slight loss of the catalytic activity and negligible copper (Cu) leaching. Some other advantages of this method are the short reaction time, high yield, easy separation of the catalyst by the external magnetic field, and easy workup procedure.

Shape-controlled CuxCe1-xO2 nanorods catalyst and the active components functioned in selective oxidation of CO in hydrogen-rich stream

A novel shape-controlled CuxCe1-xO2 nanorods catalyst is synthesized with a simple coprecipitation method at room temperature and Cu(I) chloride as copper sources for the first time. Various analysis methods (XRD Rietveld Refinement, N2 adsorption-desorption, dynamic OSC, XPS, HRTEM, H2-TPR and In situ DRIFTs) and catalytic activity test techniques are used to investigate the structural properties and the catalytic performance of the catalysts in CO-PROX. Introducing copper dopant into ceria nanorods has positive effect on enriching the lattice distortion, oxygen vacancy concentration and the lattice oxygen mobility of ceria support. The incorporation of copper ions generates two main types of active copper species that play different roles in CO-PROX. Specifically, the highly dispersed CuOx species determine the low-temperature CO oxidation activity, while strongly bound Cu-[Ox]-Ce species at the copper-ceria interface regulates the high-temperature CO oxidation activity of the catalyst. Appropriate copper doping (7–11 wt %) is in favor of forming sufficient CuOx species highly dispersed on the surface of ceria nanorods and accelerating the oxygen mobility, as well as strengthening the copper-ceria interaction in the catalyst, which significantly improves its catalytic activity and broadens the temperature window in CO-PROX.

A comparative study of CO oxidation over Cu-O-Ce solid solutions and CuO/CeO2 nanorods catalysts

The distribution of copper species (on the surface or in the bulk of CeO2 support) and the interfacial interactions between CuO and CeO2 are critical in understanding the synergistic effect on the catalytic activity of CeO2 supported CuO catalysts. In this report, Cu-O-Ce solid solutions and CuO impregnated on CeO2 nanorods catalysts (CuO/CeO2) with various compositions were prepared using thermal decomposition and hydrothermal methods, to understand the distribution effect of copper species on low temperature CO oxidation. The incorporation of copper ions into CeO2 lattice in both types of catalysts was confirmed by X-ray diffraction (XRD), Raman spectroscopy, and hydrogen temperature programmed reduction (H2-TPR) analysis, indicating a strong CuO-CeO2 interfacial interaction and formation of oxygen vacancies which compensates the charge difference between copper (I/II) and cerium (III/IV) ions. A series of temperature programmed reduction-temperature programmed oxidation (TPR-TPO) thermal cycling studies were conducted to understand the interactions between three assigned copper species (α, β, and γ) with CeO2 support and the corresponding catalytic performance of the catalysts. In addition, an improved low temperature catalytic performance for the CuO/CeO2 nanorods catalysts was observed, which was attributed to stronger interactions between copper species and CeO2 nanorods enriched with surface defects (steps and voids etc.).