Copper Ions Research Articles

Glial swip-10 controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis

Cuprous copper [Cu(I)] is an essential cofactor for enzymes that support many fundamental cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly reliant on mitochondrial production of ATP, with many neurodegenerative diseases, including Parkinson's disease, associated with diminished mitochondrial function. The gene MBLAC1 encodes a ribonuclease that targets pre-mRNA of replication-dependent histones, proteins recently found in yeast to reduce Cu(II) to Cu(I), and when mutated disrupt ATP production, elevates oxidative stress, and severely impacts cell growth. Whether this process supports neuronal and/or systemic physiology in higher eukaryotes is unknown. Previously, we identified swip-10, the putative Caenorhabditis elegans ortholog of MBLAC1, establishing a role for glial swip-10 in limiting dopamine (DA) neuron excitability and sustaining DA neuron viability. Here, we provide evidence from computational modeling that SWIP-10 protein structure mirrors that of MBLAC1 and locates a loss of function coding mutation at a site expected to disrupt histone RNA hydrolysis. Moreover, we find through genetic, biochemical, and pharmacological studies that deletion of swip-10 in worms negatively impacts systemic Cu(I) levels, leading to deficits in mitochondrial respiration and ATP production, increased oxidative stress, and neurodegeneration. These phenotypes can be offset in swip-10 mutants by the Cu(I) enhancing molecule elesclomol and through glial expression of wildtype swip-10. Together, these studies reveal a glial-expressed pathway that supports systemic mitochondrial function and neuronal health via regulation of Cu(I) homeostasis, a mechanism that may lend itself to therapeutic strategies to treat devastating neurodegenerative diseases.

Multifunctional Copper-Phenolic Nanopills Achieve Comprehensive Polyamines Depletion to Provoke Enhanced Pyroptosis and Cuproptosis for Cancer Immunotherapy.

The overexpression of polyamines in tumor cells contributes to the establishment of immunosuppressive microenvironment and facilitates tumor growth. Here, it have ingeniously designed multifunctional copper-piceatannol/HA nanopills (Cu-Pic/HA NPs) that effectively cause total intracellular polyamines depletion by inhibiting polyamines synthesis, depleting intracellular polyamines, and impairing polyamines uptake, resulting in enhanced pyroptosis and cuproptosis, thus activating a powerful immune response to achieve anti-tumor therapy. Mitochondrial dysfunction resulting from overall intracellular polyamines depletion not only leads to the surge of copper ions in mitochondria, thereby causing the aggregation of toxic proteins to induce cuproptosis, but also triggers the accumulation of reactive oxygen species (ROS) within mitochondria, which further upregulates the expression of zDHHC5 and zDHHC9 to promote the palmitoylation of gasdermin D (GSDMD) and GSDMD-N, ultimately inducing enhanced pyroptosis. Then the occurrence of enhanced pyroptosis and cuproptosis is conductive to remodel the immunosuppressive tumor microenvironment, thus activating anti-tumor immune responses and ultimately effectively inhibiting tumor growth and metastasis. This therapeutic strategy of enhanced pyroptosis and cuproptosis through comprehensive polyamines depletion provides a novel template for cancer immunotherapy.

Increasing electrochemical carbon dioxide reduction to methane via a novel copper-based conductive metal organic framework

The development of a new system for the electrochemical carbon dioxide reduction reaction (ECO2RR) to methane (CH4) is challenging, and novel conductive metal organic frameworks (c-MOFs) for efficient ECO2RR to CH4 are critical to this system. Here, we report a novel c-MOF, copper-pyromellitic dianhydride-2-methylbenzimidazole (Cu-PD-2-MBI), in which the introduction of electron-withdrawing 2-methylbenzimidazole (2-MBI) into the copper-pyromellitic dianhydride (Cu-PD) interlayer elevated the valence of copper (Cu) ions, which improved the ECO2RR performance of Cu-PD-2-MBI. Cu-PD-2-MBI was tested in a flow cell, and the Faradaic efficiency of CH4 reached 73.7 %, with a corresponding partial current density of −428.3 mA·cm−2 at −1.3 V, which was higher than those of most reported Cu-based catalysts. Further exploration via theoretical calculations indicated that the intercalated 2-MBI in Cu-PD-2-MBI induced a shift in the d-band center in the Cu sites from −2.63 to −1.86 eV and reduced the formation energy of the *COOH and *CHO intermediates in the process of generating CH4 compared with those of the reference Cu-PD catalyst.

Inhibitory activity and mechanism of thiosemicarbazide derivatives on tyrosinase and their anti-browning activity in fresh apple juice

Exploring tyrosinase inhibitors has been an effective way to find promising anti-browning agents in the food industry. Therefore, a class of thiosemicarbazide derivatives (4a-4m) were synthesized and we investigated the inhibitory mechanism on tyrosinase by fluorescence quenching, copper ion chelating and UV spectra study etc. 2-(2-Chlorobenzyl) hydrazine-1-carbothioamide (4f) (IC50 = 1.21 ± 0.02 μM) is the most active compound of all derivatives, which was defined as a mix-type inhibitor. Additionally, molecular docking and copper ions chelating studies indicated that compound 4f has the ability to inhibit the tyrosinase activity by chelating the copper ions in the active region. Furthermore, compound 4f also exhibited lower cytotoxicity, excellent aqueous solubility and outstanding anti-browning capacity in fresh apple juice. These findings indicated these derivatives could provide more possibility for developing more safer and effective anti-browning agents.

Recycled Jute Non-Woven Material Coated with Polyaniline/TiO2 Nanocomposite for Removal of Heavy Metal Ions from Water.

Growing volumes of textile waste and heavy metal pollution of water are emerging environmental challenges. In an attempt to tackle these issues, a non-woven sorbent based on jute fibers was fabricated by recycling the textile waste from the carpet industry. The influence of contact time, concentration, pH and temperature on the sorption of lead and copper ions from aqueous solutions was studied. In order to enhance the sorption capacity of the non-woven material, in situ synthesis of polyaniline (PANI) in the presence of TiO2 nanostructures was performed. The contribution of TiO2 nanoparticles and TiO2 nanotubes to the uniformity of PANI coating and overall sorption behavior was compared. Electrokinetic measurements indicated increased swelling of modified fibers. FTIR and Raman spectroscopy revealed the formation of the emeraldine base form of PANI. FESEM confirmed the creation of the uniform nanocomposite coating over jute fibers. The modification with PANI/TiO2 nanocomposite resulted in a more than 3-fold greater sorption capacity of the material for lead ions, and a 2-fold greater absorption capacity for copper ions independently of applied TiO2 nanostructure. The participation of both TiO2 nanostructures in PANI synthesis resulted in excellent cover of jute fibers, but the form of TiO2 had a negligible effect on metal ion uptake.

Thiophene appended schiff base probe for selective ‘turn-on’ response for copper (ii) ion and their applications in live cell imaging Thiophene appended schiff base probe for selective ‘turn-on’ response for copper (ii) ion and their applications in live cell imaging

In this research, we have synthesized a thiophene Schiff base from 5-phenyl thiophene-2-carboxaldehyde and 2-thiophene carboxylic acid hydrazide and characterized by using FT-IR NMR, HRMS and SC-XRD analysis techniques. The probe exhibited a selective turn-on fluorescence response for Cu2+ over 20 other common metal ions in a CH3CN (9:1, v/v) solution. The Job’s plot represents a 1:1 binding complexation mode and further DFT study was carried out to aid in understanding the geometric structure and interaction of the ligand and Cu2+. The detection limit (LOD) and limit of quantification (LOQ) were found to be 20 nM and 69 nM respectively. Furthermore, the probe’s sensing ability was tested in HeLa cells and their fluorescence imaging also supported the effective turn-on response towards Cu2+ ion.

Tri-source integrated adenosine triphosphate complexed copper ions anchored to boron nitride surfaces for enhancing flame protection of waterborne epoxy coatings

The abundant C, P, and N elements in the structure of adenosine triphosphate (ATP) can act as carbon, acid, and gas sources, and thus can be used as an efficient intumescent flame retardant. Here, a layer of polydopamine (PDA) with polyhydroxyl groups was firstly loaded on the surface of BN to provide a bridging effect for the surface modification of BN. Then, ATP-Cu was immobilized on the BN surface by complexation of ATP with Cu2+, resulting in an efficient inorganic-organic-metal composite flame retardant (BNP@ATP-Cu). This composite flame retardant effectively combined the high barrier effect of BN, the high swelling property of ATP and the catalytic carbon formation activity of Cu2+. The experimental results revealed that the EP loaded with BNP@ATP-Cu showed the lowest backside temperature (171.2 °C), indicating the highest thermal barrier effect. Moreover, BNP@ATP-Cu/EP exhibited the most significant swelling characteristics (22.7 mm, 17.46) and smoke suppression effect (42.8 %). In contrast, the carbon residue of BNP@ATP-Cu/EP (30.8 %) was significantly higher than that of the other coated samples, which was related to the combined effect of BN and ATP-Cu. The above relevant results fully demonstrated the effectiveness of the composite flame retardants in improving the fire resistance of epoxy coatings.

Cu(I)-Induced 'Click Reaction' Involving Coordination and Covalent Assembly of Hybrid Borates for the Electrocatalytic CO2 Reduction.

The design and synthesis of hybrid borates by the organic ligand modification method are urgent and undeveloped areas of research. It is difficult to directly integrate organoboronic acids within inorganic borate chemistry by adopting the traditional preparation approaches. This work reports a facile synthetic method to synthesize a large family of pyrazole molecule-protected borates in a rapid and precise manner under mild conditions. A unique cyclic eight-membered B4O4-ring has been identified as the cluster core for all these hybrid borates with two different conformations (boat and crown). This strategy can be applied to a system of pyrazolyl molecules to generate such hybrid borates in two independent routes from organoboronic or inorganic boric acids. Furtherly, the mechanism of 'click reaction' between boric acid and pyrazole induced by copper ions has been proposed based on the synthetic conditions and the structure of intermediate. Due to the bimetallic Cu sites and the functional surfaces, these materials can be used as electrocatalysts for CO2 reduction reaction and efficiently enhance the selectivity of HCOOH and C2H4. Our strategy can be regarded as a typical template technique for organic molecule-protected borates.

Alginate-derived biomass carbon‑molybdenum disulfide heterogeneous materials: Vertically grown/uniformly dispersed molybdenum disulfide nanosheets/nanoflowers for wastewater treatment

In order to improve the dispersion of molybdenum disulfide (MoS2) and enhance the performance of MoS2, two alginate-derived biomass carbon-MoS2 (BC-MoS2) composites: CMB/CMS, were prepared by introducing BC during the synthesis of MoS2 by hydrothermal. The effects of different gels, times and temperatures of the synthesized BC-MoS2 were investigated, and the adsorption capacity for methylene blue (MB), basic fuchsin (BF) and copper ions (Cu2+) was tested. The results indicated that the vertical growth of MoS2 on the BC surface could be realized when using xero-gel, while the BC and MoS2 were mixed uniformly when using wet-gel. Compared with MoS2, the hydrophilicity and water dispersibility of BC-MoS2 were greatly improved, and BC-MoS2 had better adsorption capacity for MB/BF/Cu2+ (99.61/86.83/60 mg/g). The adsorption mechanism exhibits that the adsorption force of BC-MoS2 on MB/BF is mainly based on the electrostatic force, and the adsorption on Cu2+ comes from the electrostatic force and the Lewis soft-soft interaction. This study dramatically enriches the application of transition metal chalcogenides and provides a meaningful reference for wastewater treatment.

NMR-Based Structural Insights on Folic Acid and Its Interactions with Copper(II) Ions

NMR-Based Structural Insights on Folic Acid and Its Interactions with Copper(II) Ions

Biochemical and structural insights of a recombinant AA16 LPMO from the marine and sponge-symbiont Peniophora sp

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that oxidize polysaccharides, leading to their cleavage. LPMOs are classified into eight CAZy families (AA9-11, AA13-17), with the functionality of AA16 being poorly characterized. This study presents biochemical and structural data for an AA16 LPMO (PnAA16) from the marine sponge symbiont Peniophora sp. Phylogenetic analysis revealed that PnAA16 clusters separately from previously characterized AA16s. However, the structural modelling of PnAA16 showed the characteristic immunoglobulin-like fold of LPMOs, with a conserved his-brace motif coordinating a copper ion. The copper-bound PnAA16 showed greater thermal stability than its apo-form, highlighting copper's role in enzyme stability. Functionally, PnAA16 demonstrated oxidase activity, producing 5 μM H₂O₂ after 30 min, but showed 20 times lower peroxidase activity (0.27 U/g) compared to a fungal AA9. Specific activity assays indicated that PnAA16 acts only on cellohexaose, generating native celloligosaccharides (C3 to C5) and oxidized products with regioselective oxidation at C1 and C4 positions. Finally, PnAA16 boosted the activity of a cellulolytic cocktail for cellulose saccharification in the presence of ascorbic acid, hydrogen peroxide, or both. In conclusion, the present work provides insights into the AA16 family, expanding the understanding of their structural and functional relationships and biotechnological potential.

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.

Chalcone derived bis-organosilane and its magnetic nanoparticles: Unveiling precision in selective Cu(II) ion detection and elucidating biocompatibility

The escalating concern regarding the adverse effects of metal ion toxicity on both human health and environmental ecosystems necessitates the development of efficient detection methodologies. This study presents a focused investigation on the selective and sensitive detection of Cu(II) ions employing hybrid magnetic nanoparticles derived from chalcone-based bis-organosilane. These nanoparticles exhibit a notably low detection limit in the nano-scale range, rendering the sensor highly sensitive to Copper(II) ion detection while maintaining robust anti-interference capabilities, even in the presence of diverse metal ions. Real sample analysis confirms the sensor’s efficacy in detecting Cu(II) ions below WHO-prescribed levels. Computational analyses reveal molecular interactions and biological activities, including potent antibacterial and antioxidant properties, suggesting promising applications. Furthermore, the biological effectiveness of chalcone-derived bis-organosilane is investigated, unveiling notable antibacterial efficacy and also exhibiting potential as a scavenger of free radicals, indicating promising applications in both antibacterial and antioxidant domains.

The synthesis of Fe3O4@SiO2-NNO-CuII nanocatalyst and investigation of its application in the synthesis of imidazo[1,2-a]pyridines

In this study, a tridentate Schiff base ligand obtained from the condensation of salicylaldehyde and 3-amino-1,2,4 triazole was covalently immobilized on the surface of 3-chloro-trimethoxysilane-functionalized magnetic nanoparticles. This nitrogen and oxygen-rich compound provides donor arms for the coordination of copper ions. The prepared nanocatalyst (Fe3O4@SiO2-NNO-CuII) has been characterized by various techniques including FT-IR, EDX, SEM, VSM, XRD and ICP analysis and used as an efficient recyclable catalyst for the synthesis of imidazo[1,2-a]pydidines. Imidazo[1,2-a]pyridine products were obtained through the coupling reaction of substituted benzaldehydes, 2-aminopyridine derivatives and phenylacetylene under solvent-free conditions in high yields and short reaction times.

Diffusive Memristor with CuS Nanoparticles Embedded in Polymeric Film as Artificial Nociceptor.

The threshold behavior and the ion diffusion dynamics in diffusive volatile memristors have a very uncanny resemblance to the transduction process of biological nociceptors. Hence, the diffusive memristors are considered the most suited for making artificial nociceptive systems. To facilitate their widespread adoption, it is imperative to develop polymeric or organic-inorganic hybrid material-based diffusive memristors that are economical, biocompatible, and easily processable. In this study, we present a cluster-type polymeric diffusive memristor where copper is used as the active top electrode. The switching medium comprises copper(II) sulfide (CuS) nanoparticles embedded in poly(ethylene oxide) (PEO). The devices show electrochemical metalization (ECM)-type and bidirectional diffusive volatile memory with high nonlinearity (104) and turn-on slope (5.6 mV/dec). They reliably remain diffusive volatile with up to 10 wt % CuS in PEO and for a wide range of compliance (10-6 to 10-2 A) without transitioning to the bipolar nonvolatile type. The low reduction potential of CuS and optimal segmental dynamics of PEO work synergistically to ensure stable and reproducible diffusive memory. The CuS nanoparticles act as bipolar electrodes, undergoing local oxidation and reduction under the influence of the bias. The switching of resistance states in the CuS-PEO memristors is attributed to the formation of cluster-type filaments between CuS nanoparticles within the PEO matrix supported by the participation of copper ions from the top Cu electrode. The observation of low filament temperature and the independence of on-state resistance with respect to the device area and temperature further corroborate the cluster-type filament in CuS-PEO memristors. Using a 5 wt % CuS-based device, an artificial nociceptor is realized, which successfully mimics most of the nociceptive plasticities such as threshold, relaxation, no adaptation, and sensitization.

The electrochemical corrosion behavior and antibacterial properties of Cu-xFe alloy

Copper-based alloys have garnered significant attention for their potential in antimicrobial applications aimed at mitigating medical-related infections. Nonetheless, the alloying elements in conventional copper alloys frequently exhibit biotoxicity. This study explored the corrosion behavior, antimicrobial activity, and ion release of Cu–Fe alloys with varying iron contents and aging treatment. The results indicate that increasing the iron content in Cu–Fe alloys and applying appropriate aging treatment can enhance both the antibacterial efficiency and corrosion rate. Transmission electron microscopy (TEM) observations revealed a corrosion mechanism in which dispersed iron phases act as nucleation sites. These nanoscale precipitates increase the Cu/Fe interfacial area, thereby promoting ion release at the interface. Furthermore, in-situ scanning electron microscopy (SEM) revealed that corrosion products are more likely to detach in iron-rich segregated areas, which effectively promotes the sustained release of copper ions.

Ionophore-based nanospheres enable selective and sensitive fluorescence detection of copper ions

A novel ionophore-based fluorescent nanosensor has been successfully fabricated for the sensitive and selective detection of Cu2+ ions. The nanosensor was constructed through self-assembly of amphiphilic block copolymers, incorporating elesclomol as a Cu2+ ionophore and long-chain dialkylcarbocyanines (DiD) as a fluorescent dye. This design exhibits an "ON/OFF" fluorescence response, where Cu2⁺ ions are selectively sequestered within the nanosensors, resulting in fluorescence quenching of DiD. This strategy enables rapid and highly selective Cu2⁺ sensing with remarkable fluorescence quenching efficiency (up to 93.5 %) and an exceptionally low detection limit of 28.6 nM. The linear detection range extends over two orders of magnitude (0.05–10 μM). Furthermore, the feasibility of this nanosensor for practical applications was confirmed through successful determination of Cu2+ in real water and beer samples, with excellent recovery rates. This nanosensor offers advantages of simplicity, rapidity, and cost-effectiveness, holding significant potential for sensitive and selective Cu2+ detection in various biological and environmental samples.

CEBPB dampens the cuproptosis sensitivity of colorectal cancer cells by facilitating the PI3K/AKT/mTOR signaling pathway.

Cuproptosis is a novel pathway that differs from other forms of cell death and has been confirmed to be applicable for predicting tumor prognosis and clinical treatment response. However, the mechanism underlying the resistance of colorectal cancer (CRC) to cuproptosis at the molecular level has not been elucidated. Using bioinformatics analysis, the expression of CCAAT/enhancer-binding protein beta (CEBPB) in CRC tissues and its enrichment in biological processes were detected. Quantitative reverse transcription polymerase chain reaction and western blotting (WB) were employed to test the expression of CEBPB in CRC cells. WB was utilized to assess the levels of proteins related to cuproptosis and the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. The MTT assay was used to test cell viability. Cell proliferation was assessed by a colony formation assay. Transwell assays were used to measure cell migration and invasion ability. DLAT-aggregate formation was determined by immunofluorescence. CEBPB was highly upregulated in CRC cells to enhance cell viability, proliferation, migration, and invasion. CEBPB was strongly implicated in copper ion homeostasis and the mTOR signaling pathway in CRC. In a CRC cuproptosis cell model, rescue experiments revealed that a PI3K/AKT/mTOR pathway inhibitor attenuated the promoting effect of CEBPB overexpression on the PI3K/AKT/mTOR pathway and rescued the sensitivity of CRC to cuproptosis. This work demonstrated that CEBPB can activate the PI3K/AKT/mTOR signaling pathway, thereby decreasing the sensitivity of CRC to cuproptosis. These data suggested that targeting CEBPB or the PI3K/AKT/mTOR pathway may enhance the sensitivity of CRC patients to cuproptosis, providing a combined therapeutic strategy for cuproptosis-induced therapy.

Organically coordinated Cu(II) activated peroxymonosulfate for enhanced degradation of emerging contaminants

Copper ion Cu(II) is generally considered ineffective in activating peroxymonosulfate (PMS). However, our study demonstrates that organically coordinated Cu(II), namely, org-Cu(II) with contaminants such as amoxicillin (AMO), ofloxacin (OFX), sulfadiazine (SDZ), and tetracycline (TET) can efficiently activate PMS under neutral conditions, leading to faster degradation of these emerging contaminants. In contrast, organic contaminants that do not coordinate with Cu(II) do not facilitate PMS activation. Unlike traditional PMS-induced advanced oxidation processes (AOPs), our study identifies trivalent Cu(III) as the primary oxidant intermediate, with monovalent Cu(I) serving as its precursor. In addition, basic conditions was found to be beneficial for the degradation of target pollutants in org-Cu(II)/PMS systems. Moreover, this promotion effect extends to realistic wastewater, suggesting promising application prospects. The potential mechanism of the rate-limiting reduction step from Cu(II) to Cu(I) was further investigated. The interaction strength between the lowest unoccupied molecular orbital (LUMO) of the copper complex formed with organic compounds and the highest occupied molecular orbital (HOMO) of PMS influences the energy of the bonding orbitals. Coordination with organic ligands alters the LUMO of Cu(II), facilitating electron transfer from the HOMO of PMS to copper. This process activates PMS, ultimately leading to the production of Cu(I) and Cu(III). These findings deepen our understanding of PMS-induced AOPs for degrading emerging contaminants and underscore the importance of further research into PMS activation by Org-Cu(II).

Highly Active Cerium Oxide Supported Solution Combustion Cu/Mn Catalysts for CO-PrOx in a Hydrogen-Rich Stream

Mono- and di-substituted cerium oxide catalysts, viz. Ce0.95Cu0.05O2-δ, Ce0.90Cu0.10O2-δ, Ce0.90 Cu0.05Mn0.05O2-δ, Ce0.85Cu0.10Mn0.05O2-δ, and Ce0.80Cu0.10Mn0.10O2-δ, were synthesized via a one-step urea-assisted solution combustion method. The elemental composition and textural and structural properties of the catalysts were determined by various physical, electronic, and chemical characterization techniques. Hydrogen temperature-programmed reduction showed that co-doping of copper and manganese ions into the CeO2-δ lattice improved the reducibility of copper. Powder XRD, XPS, HR-TEM, and Raman spectroscopy showed that the catalysts were a singled-phased, solid-solution metal oxide with a cerium oxide cubic fluorite (cerianite) structure, and evidence of oxygen vacancies was observed. Catalytic results in the preferential oxidation of CO in a hydrogen-rich stream showed that complete CO conversion occurred between 150 and 180 °C. Furthermore, at 150 °C, Ce0.90Cu0.05Mn0.05O2-δ, Ce0.90 Cu0.10O2-δ, and Ce0.85Cu0.10Mn0.05O2-δ catalysts were the most active, achieving complete CO conversion and CO2 selectivity of 81, 79, and 71%, respectively. The catalysts performed moderately in the presence of CO2 and water, with the Ce0.90Cu0.05Mn0.05O2-δ catalyst giving a CO conversion of 80% in CO2, which decreased to about 60% when water was added.