Role Of Cu Research Articles

Role of metal Cu(II) and Ag(I) on molecular structure of 4-amino-N-(2, 6-dimethoxypyrimidin-4-yl) benzenesulfonamide in presence of 3-methyl pyridine: Synthesis, spectral, crystallographic and DNA interaction studies

Mononuclear and dinuclear copper and silver complexes of bidentate sulfadimethoxine (sdmz), 4-Amino-N-(2,6-dimethoxypyrimidin-4-yl)benzenesulfonamide, ligand in presence of secondary ligand 3-methyl pyridine have been synthesized and characterized by X-ray diffraction and spectroscopic techniques. In crystal structure of mononuclear copper complex [{Cu(C12H12N4O4S).(C6H7N)}.(C6H7N)]; (complex 1), copper occupies special crystallographic position exhibiting a distorted octahedral geometry. A free solvent 3-methyl pyridine per asymmetric unit, completes the crystal structure of copper complex. Silver complex of bidentate sdmz ligand formulated as [Ag2(C12H12N4O4S)2(C6H7N)2]; (complex 2), crystallizes in centrosymmetric space group P21/c with two molecules per asymmetric unit. In the silver complex, silver located in a distorted tetrahedral coordination displaying argentophilic interactions with Ag-Ag separation distance of 2.8177(5) Å in molecule A and 2.8227(5) Å in molecule B. Secondary ligand plays a decisive role towards formulating coordination geometry as well as the molecular stability of both the complexes. Hirshfeld surface (HS) analysis reveals the quantitative contributions of different interactions on HS. Lipophilicity index (log P value) represents significant biological activity of the molecules, correlates well with the contribution of CH…π interaction. Both the complexes of sdmz ligand are screened for diverse biological activities to investigate the role of Cu(II) and Ag(I) metals on the molecular conformation of sdmz complexes. The interaction ability of both the metal complexes to DNA studied by absorption spectroscopy and viscosity measurement along with molecular docking study, conformed the intercalation mode of DNA binding with comparatively higher binding strength (Kb) for silver complex followed by copper complex and free sdmz ligand. The data of MIC against panel of gram positive and gram negative organisms confirm that both the metal complexes of sdmz possesses better inhibitory activities than that of sdmz ligand. Being less toxic, copper complex exhibits comparatively better response towards the panel of the gram positive and gram negative bacteria except B. subtilis. The observed differences in molecular structures and so on the biological activities of copper and silver complexes of sdmz-picoline ligand, point towards the impact of the respective metals.

Role of Cu on the mechanical properties and microstructures evolution of Al-xCu-1Li-0.4Mg–1Zn-0.1Zr alloys

In this paper, mechanical properties and microstructures of the cast and extruded Al-xCu-1Li-0.4Mg–1Zn-0.1Zr alloys (x = 2.0, 3.0, 4.0, 4.5, 5.5, 6.5 wt%) were investigated. The results showed that the as-cast micrographs of alloys with different Cu content primarily consist of dendritic α-Al grains, and the intermetallic phases at the grain boundaries were Cu and Zr rich phases. After solution treatment, no recrystallization took place in extruded alloys, and the alloys mainly represented mixed textures composed of <111> and <100> fibers. Cu significantly affected the precipitation behavior of the extruded alloys. Only T1 (Al2CuLi) phases were observed in T6 (aging at 175 °C for 32 h) and T8 (3% pre-strain followed by aging at 150 °C for 32 h) treated alloy with 2 wt% Cu. Further increasing Cu contents (4.5 and 6.5 wt%) enabled the co-precipitation of T1 and θ' (Al2Cu) phases, as well as increased their density. In addition, the microstructures of grain boundaries of alloys with different Cu content showed dramatic differences. T1 phases precipitated at the grain boundaries of alloy containing 2 wt% Cu, while rare precipitation of T1 phases was observed at the grain boundaries of alloy with 6.5 wt% Cu. The yield strength (YS) of the alloys increased with the Cu content and the elongation (EL) showed an opposite trend. A good combination of ultra-high strength (YS = 684 MPa, ultimate tensile strength = 726 MPa) and ductility (EL = 6.3%) was obtained in T8 treated alloy containing 4.5 wt% Cu. The presence of the undesired coarse T2 (Al6CuLi3) phases at the grain boundaries resulted in the premature failure of the high Cu content alloys.

Copper homeostasis: Emerging target for cancer treatment

Copper (Cu) is an essential micronutrient involved in a variety of fundamental biological processes. Recently, disorder of Cu homeostasis can be observed in many malignancies. Elevated Cu levels in serum and tissue are correlated with cancer progression. Hence, targeting Cu has emerged as a novel strategy in cancer treatment. This review provides an overview of physiological Cu metabolism and its homeostasis, followed by a discussion of the dysregulation of Cu homeostasis in cancer and the effects of Cu on cancer progression. Finally, recent therapeutic advances using Cu coordination complexes as anticancer agents, as well as the mechanisms of their anti-cancer action are discussed. This review contributes full comprehension to the role of Cu in cancer and demonstrates the broad application prospect of Cu coordination compounds as potential therapeutic agents.

Distinct effects of copper on the degradation of β-lactam antibiotics in fulvic acid solutions during light and dark cycle

This study revealed the dual roles of Cu(II) on the β-lactam antibiotics degradation in Suwannee River fulvic acid (SRFA) solution during day and night cycle. Amoxicillin (AMX) and ampicillin (AMP) were selected as the representative β-lactam antibiotics. Cu(II) played a key role in the dark degradation of AMX and AMP via catalytic hydrolysis and oxidation. However, Cu(II) mainly exhibited an inhibitory effect on SRFA-involved photochemical degradation of AMX and AMP. In the presence of 500 nM of Cu(II), the degradation rate of AMX and AMP in the light condition were around 5 times higher than that in the dark condition, suggesting the photodegradation of β-lactam antibiotics was much more pronounced than catalyzed hydrolysis and oxidation. The triplet excited state of SRFA (3SRFA∗) primarily contributed to AMX and AMP photodegradation. Hydroxyl radicals (•OH) and singlet oxygen (1O2) exhibited limit impacts. The redox cycle of Cu(II)/Cu(I) restricted the electron transfer pathway of 3SRFA∗ with AMX and AMP. During the day and night cycles for 48 h, Cu(II) served as a stronger inhibitor rather than a promotor. These findings highlight the interactions between Cu(II) and SRFA are distinct under day and night conditions, which could further affect the fate of β-lactam antibiotics in natural environments.

Cupric ion in combination with hydrogen peroxide and hydroxylamine applied to inactivation of different microorganisms

The microbial inactivation by cupric ion (Cu(II)) in combination with hydrogen peroxide (H2O2) and hydroxylamine (HA) was investigated for twelve different microorganisms (five Gram-negative bacteria, three Gram-positive bacteria, and four bacteriophages). The inactivation efficacy, protein oxidation, and RNA (or DNA) damage were monitored during and after treatment by Cu(II), Cu(II)/HA, Cu(II)/H2O2 and Cu(II)/HA/H2O2. The rate of microbial inactivation by the (combined) microbicides generally increased in the order of Cu(II) < Cu(II)/H2O2 < Cu(II)/HA < Cu(II)/HA/H2O2; Cu(II)/HA/H2O2 resulted in 0.18–0.31, 0.10–0.18, and 0.55–3.83 log inactivation/min for Gram-negative bacteria, Gram-positive bacteria, and bacteriophages, respectively. The degrees of protein oxidation and RNA (or DNA) damage increased in the order of Cu(II) < Cu(II)/HA < Cu(II)/H2O2 < Cu(II)/HA/H2O2. In particular, Cu(II)/HA/H2O2 led to exceptionally fast inactivation of the viruses. Gram-positive bacteria tended to show higher resistance to microbicides than other microbial species. The microbicidal effects of the combined microbicides on the target microorganisms were explained by the roles of Cu(I) and Cu(III) generated by the redox reactions of Cu(II) with H2O2, HA, and oxygen. Major findings of this study indicate that Cu(II)-based combined microbicides are promising disinfectants for different waters contaminated by pathogenic microorganisms.

Determining Roles of Cu0 in the Chemosynthesis of Diols via Condensed Diester Hydrogenation on Cu/SiO2 Catalyst

AbstractCopper‐based catalyst was applied in the condensed diester hydrogenation with unexpected high selectivity (∼100 %) to 1,6‐hexanediol. On basis of the mass transfer analysis and kinetics results, the reaction rate of the condensed diester hydrogenation was deduced to be controlled by the activation of hydrogen on Cu0 sites, which was further demonstrated by the correlations between the catalytic activity and different copper species. Importantly, this catalysis mechanism is different with that of gas‐phase diester hydrogenation, which is generally determined by the adsorption of ester on Cu+ species.

Important role of Cu in suppressing bipolar conduction in Bi-rich (Bi,Sb)2Te3

Cu doping has been known to enhance thermoelectric performance of p-type (Bi,Sb)2Te3 alloys by suppressing bipolar conduction at higher temperatures. However, detailed mechanisms are not provided yet. Herein, we investigate the unchallenged role of Cu doping in (Bi,Sb)2Te3 alloys by means of Bi-rich compositions of Bi0.6Sb1.4Te3 and Bi0.7Sb1.3Te3, which were chosen since they exhibit much inferior thermoelectric performance owing to severe bipolar conduction. It was found that Cu doping increases non-degenerate mobility and density-of-states effective mass of valence band as well as hole concentration. Small amount of Cu doping enhanced maximum thermoelectric figure-of-merit of Bi0.6Sb1.4Te3 composition from 0.25 to 0.98.

Interconnection between Trait, Structure, and Composition of Grain Boundaries in Cu(In,Ga)Se2 Thin‐Film Solar Cells

AbstractGrain boundaries (GBs) are crucial for solar cells incorporating polycrystalline absorbers and particularly for those characterized by small grain sizes (≈2 µm). For example, random GBs in Si solar cells are found to have a detrimental effect on the cell performance being characterized by an increased recombination activity relative to grains. Yet, their role in Cu(In,Ga)Se2 (CIGS) solar cells still remains controversial. The recent electron‐beam‐induced current (EBIC) study shows that 58% of the GBs in CIGS exhibit enhanced electrical properties considered to be benign (for the device performance). Yet, they coexist with 16% detrimental GBs (reduced electrical properties) and 27% neutral ones (no change in electrical property when compared with the bulk). In the present study, these different GBs are investigated by combining EBIC with electron backscattered diffraction and atom probe tomography techniques on identical GBs. For the first time, a successful correlation is shown (for any device) that interconnects the GB characteristics to its composition. Sufficient statistics demonstrate that the collective fluctuations of all elements at GBs determine its trait. In general, benign (detrimental) GBs are characterized by Cu depletion (enrichment) that favored the formation of donor (acceptor) defects.

Functional Role of Fe, Cu-Doping in Ni-Based Perovskite Electrocatalysts for Oxygen Evolution Reaction

Water electrolysis is of vital importance to store renewable energy and the development of efficient, inexpensive and stable electrocatalysts for oxygen evolution reaction (OER) is essential, which requires much more understanding of the structural and the element classification. Here, a series of [Formula: see text]Fex[Formula: see text][Formula: see text] perovskites have been assessed as potential noble-metal-free OER electrocatalysts prepared by sol–gel method. Moreover, the functional role of Cu and Fe amount on the B-site of perovskites for OER electrocatalytic performance was evaluated. [Formula: see text][Formula: see text][Formula: see text] materials exhibited the highest intrinsic activities in 0.1[Formula: see text]M KOH for OER with an onset potential of 1.56[Formula: see text]V, a Tafel slope of 76[Formula: see text]mV[Formula: see text][Formula: see text], slightly lower than that of benchmark perovskite-type electrocatalyst [Formula: see text][Formula: see text]C[Formula: see text][Formula: see text]O3 (BSCF). The above results demonstrate that Cu element in the B-site of perovskites had little effect on the OER performance, and [Formula: see text][Formula: see text][Formula: see text] is a potential alternative electrocatalyst for OER application.

In situ synthesis of Cu+ self-doped CuWO4/g-C3N4 heterogeneous Fenton-like catalysts: The key role of Cu+ in enhancing catalytic performance

In this work, novel Cu+ self-doped CuWO4/g-C3N4 composites were in situ synthesized through a simple hydrothermal method. The CuWO4 nanoparticles with the size of about 10 nm were dispersed uniformly on the surface of g-C3N4 nanosheets. The Fenton-like catalytic results showed that the 30 wt% CuWO4/g-C3N4 composite exhibited the best catalytic activity for the degradation of organic dyes. The enhanced Fenton-like catalytic activity could be ascribed to the promoted redox cycle of Cu+/Cu2+ in the presence of abundant Cu+ as well as the synergistic effect between CuWO4 and g-C3N4 in the CuWO4/g-C3N4 composites. In addition, the highly efficient catalysts could be used repeatedly to treat variety of organic pollutants in a wide pH range at room temperature without external energy input (light, electricity and ultrasound). The reactive species quenching experiments showed that singlet oxygen played the major role in the Fenton-like reaction for the degradation of organic dyes. Based on the above results, a possible reaction mechanism was proposed in the Cu+ self-doped CuWO4/g-C3N4/H2O2 system.

Accelerated degradation of bisphenol A induced by the interaction of EGCG and Cu(II) in Cu(II)/EGCG/peroxymonosulfate process

Transition metals to activate peroxymonosulfate (PMS) has promising prospect to remove emerging organic contaminants, among which copper is an alternative because of its relatively high regulated concentration in drinking water and wide use of organic copper pesticide. Cu(I) shows good performance on the activation of PMS, while Cu(II) is reported to have no ability to activate PMS, which is the most stable valent in natural environment. In this study, degradation of bisphenol A (BPA) by Cu(II)/PMS process was significantly enhanced with involvement EGCG, because Cu(II) was transformed to Cu(I) and chelated by EGCG. Batch experiments were conducted to investigate the impacts of Cu(II), EGCG and PMS concentration and co-existing components including natural organic matters, alkalinity, and chloride ion. The impacts of solution pH and dissolved oxygen on BPA degradation were also evaluated to interpret the roles of Cu(I) and superoxide radical in Cu(II)/EGCG/PMS process, and the generated concentration of Cu(I) was determined. Possible generation pathway of Cu(III) were also proposed. By quenching experiment and electron paramagnetic resonance analysis, hydroxyl radical and sulfate radical in Cu(II)/EGCG/PMS process were confirmed to be main contributors for BPA degradation. Furthermore, transformation products of BPA were identified and their respective eco-toxicities were calculated. This work aims to unravel the interaction of EGCG and Cu(II), and provide a deep insight to the copper conversion in the presence of EGCG and PMS.

Preparation and Characterization of Nitrogen-Riched Polymer Based Materials and the Role of Cu–N Active Site in Promoting the ORR Activity of the Catalyst

A novel nitrogen-riched composite (PPYTZ/C) was firstly prepared by chemical polymerization, and then the Cu-PPYTZ/C complex was obtained by immersing the PPYTZ/C modified electrode in copper sulphate solution. For comparing the performance of the two catalysts, physical and electrochemical measurements were adopted. Wherein, physical measurements include scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). And, the electrochemical measurements include cyclic voltammetry (CV), rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE), and then the above measurement results were compared with commercial Pt/C. The CV and RDE results proved that Cu-PPYTZ/C catalyst exhibits excellent performance than that of PPYTZ/C in term of ORR activities and stability. In addition, the RRDE results also indicated that Cu-PPYTZ/C is comparable to the commercialization Pt/C in term of electron transfer numbers. In conclusion, Cu-PPYTZ/C is the potential candidate for oxygen reduction reaction catalysts, which is attribute to the role of CNx-M in Cu-PPYTZ/C catalyst as the catalytic group.

Copper is an essential regulator of the autophagic kinases ULK1/2 to drive lung adenocarcinoma.

While the transition metal copper (Cu) is an essential nutrient that is conventionally viewed as a static cofactor within enzyme active sites, a nontraditional role for Cu as a modulator of kinase signaling is emerging. We discovered that Cu is required for the activity of the autophagic kinases ULK1/2 through a direct Cu-ULK1/2 interaction. Genetic loss of the Cu transporter Ctr1 or mutations in ULK1 that disrupt Cu-binding reduced ULK1/2-dependent signaling and autophagosome complex formation. Elevated intracellular Cu levels are associated with starvation induced autophagy and sufficient to enhance ULK1 kinase activity and in turn autophagic flux. The growth and survival of lung tumors driven by KRASG12D is diminished in the absence of Ctr1, depends on ULK1 Cu-binding, and is associated with reduced autophagy levels and signaling. These findings suggest a molecular basis for exploiting Cu-chelation therapy to forestall autophagy signaling to limit proliferation and survival in cancer.

A Preliminary Study of Cu Exposure Effects upon Alzheimer's Amyloid Pathology.

A large body of evidence indicates that dysregulation of cerebral biometals (Fe, Cu, Zn) and their interactions with amyloid precursor protein (APP) and Aβ amyloid may contribute to the Alzheimer’s disease (AD) Aβ amyloid pathology. However, the molecular underpinnings associated with the interactions are still not fully understood. Herein we have further validated the exacerbation of Aβ oligomerization by Cu and H2O2 in vitro. We have also reported that Cu enhanced APP translations via its 5′ untranslated region (5′UTR) of mRNA in SH-SY5Y cells, and increased Aβ amyloidosis and expression of associated pro-inflammatory cytokines such as MCP-5 in Alzheimer’s APP/PS1 doubly transgenic mice. This preliminary study may further unravel the pathogenic role of Cu in Alzheimer’s Aβ amyloid pathogenesis, warranting further investigation.

Redox potential-dependent chalcopyrite leaching in acidic ferric chloride solutions: Leaching experiments

The redox potential dependence of chalcopyrite leaching was investigated in acidic ferric chloride solutions using a specially designed batch leaching experimental setup that accurately determined and monitored changes of solution redox potential with time. The concentration ratio of ferric (Fe3+) to ferrous (Fe2+) ions and leaching rate-redox potential relationship were then determined from measured redox potential data assuming chalcopyrite oxidation with Fe3+ occurred stoichiometrically. A distinct peak was observed in the leaching rate vs. redox potential plot; that is, the leaching rate increased with increasing redox potential, reaching a (local) maximum (i.e., the peak rate) at a certain redox potential (i.e., the peak redox potential) followed by the gradual decrease in leaching rate at higher redox potentials. For example, in the experiment performed at [Cu2+] = [Fe2+] = 0.01 kmol m−3 in HCl (0.1 kmol m−3) at 343 K, the rate continuously increased with increasing redox potential, reaching the fastest rate of 9.7 × 10−8 mol s−1 g−1 (peak rate) at 0.442 V (peak redox potential). After passing this redox potential peak, the rate started to decrease, slowing down to 2.9 × 10−8 mol s−1 g−1 at 0.487 V. Using this setup, the effects of temperature and solution composition (Cu2+, Fe3+ and HCl concentrations) on the peak rate and peak redox potential were investigated. The results showed that the peak rate increased with increasing temperature, decreased with increasing HCl and Fe3+ concentrations but was not strongly affected by Cu2+ concentration. In comparison, the peak redox potential was less dependent on the temperature and concentrations of HCl and Fe3+. Although the role of Cu2+ was apparently not crucial in the occurrence of the peak rate, it exerted a relatively strong influence on the peak redox potential; that is, the peak redox potential increased with increasing Cu2+ concentration. Based on these results, an empirical equation for the relationship between peak redox potential and Cu2+ concentration was derived.

Assessing the roles of Cu- and Ag-deficient layers in chalcopyrite-based solar cells through first principles calculations

Chalcopyrites are a demonstrated material platform for realizing efficient thin-film photovoltaics, with the most well known Cu(In,Ga)Se2 (CIGS)-based solar cells exceeding 23%. Several factors, including flexibility in tuning the absorber bandgap, enhanced surface treatments, and the electrically benign nature of common defects are responsible for the existing high performance and future promise in chalcopyrite-based photovoltaic devices. The introduction of Cu-poor phases (also known as ordered-vacancy compounds or OVCs) between the absorber and buffer layers in CIGS solar cells is known to enhance device performance; however, the overall properties and role of OVCs remain poorly understood. Using first principles calculations based on the density functional theory with screened hybrid functionals, we explore the electronic structure and stability of OVCs and their band offsets with defect-free chalcopyrite layers in Cu- and Ag-based compounds (ABX2 where A=Cu, Ag; B=In, Ga, Al; and X=S, Se). Using AB3X5 and AB5X8 stoichiometries as model OVC systems, we report on the variation of the bandgap with the A/B ratio and discuss the trends in other Cu- and Ag-based chalcopyrites beyond CuInSe2. We find that the valence and conduction bands are lower in energy in OVCs with respect to the parent ABX2 chalcopyrite owing to a reduced p–d interaction between X and A atoms. We additionally perform device-level simulations to assess the implications of the results, finding that the valence band offsets of OVCs are favorable, while the conduction band offsets of chalcopyrites beyond CuInSe2-based absorbers may be detrimental in conventional solar cell device designs.

The catalytic effect of copper ion in the bioleaching of arsenopyrite by Acidithiobacillus ferrooxidans in 9K culture medium

Bioleaching pre-treatment of arsenopyrite (FeAsS), a common mineral occurring in deposits of gold ore that makes the extraction of gold difficult, has attracted significant attention recently due to its simple operation and environmental friendliness. A critical impedance of bioleaching to its large scale industrial application is the slow leaching kinetics. Several metal cations have previously been found to accelerate the leaching process. This paper reports results from an in-depth investigation into the bioleaching of arsenopyrite including leaching experiments, thermodynamic analysis of the leaching system and physicochemical analyses of the materials. The results suggest that a passivating film consisting mainly of As2S2, As2S3 and S0 formed on the arsenopyrite surface in the initial bioleaching of 36 h in the 9K culture containing Acidithiobacillus ferrooxidans. This film disappeared when Cu2+ was added to the system. The bioleaching of arsenopyrite was efficiently improved at the Cu2+ level of 0.05 g/L with its leaching period significantly shortened from 19 d to 13 d. Based on the results, the paper also proposes possible leaching mechanisms and the role of Cu2+ in improving the rate of the leaching process. Specifically, Cu2+ is found to facilitate the oxidative dissolution of the passivating species of As2S2, As2S3 and S0 by forming Cu2S/CuS that can be rapidly oxidised by Fe3+ back to Cu2+. A catalytic cycle of Cu2+/(Cu2S/CuS) is thus likely established on the Fe3+/Fe2+ catalytic cycle, resulting in the elimination of the passivating film. The bacteria utilised the two synergistic cycles to catalyse the leaching of arsenopyrite.

Roles of Cu+ and Cu0 sites in liquid-phase hydrogenation of esters on core-shell CuZnx@C catalysts

Liquid-phase hydrogenolytic reduction of esters on Cu-based catalysts is a promising approach for synthesis of alcohols. Here, core-shell CuZnx@C materials synthesized via pyrolysis of a Zn(NO3)2-loaded metal-organic framework (MOF) were proposed, in which well-defined spacing between Cu species in the parent MOF and the homogeneous loading of a Zn salt leads to an ideal distribution and strong interaction of Cu and Zn after pyrolysis of the precursor. The as-synthesized CuZnx@C showed a much higher catalytic activity than Cu@C. This higher activity is tentatively attributed to the simultaneous presence of Cu0 and Cu+ sites at ZnO crystal domains. The resulting Cu-O-Zn sites have a high tendency to adsorb the ester in the form of a surface bound species that greatly improves the hydrogenolysis, which is the rate controlling step in the reductive pathway. A theoretical study confirms the ability of this site to bind and catalytically convert fatty acid esters.

Microstructure and tribological properties of Cu-doped VCN films: The role of Cu

Element doping has been proved to be an effective method to improve the tribological property of hard films. In this work, C and Cu element co-doping are applied to reduce the room-temperature friction coefficient of VN film and the effect of Cu content on microstructure and tribological property of Cu-doped VCN films are discussed in detail. As expected, owing to the catalytic action of Cu, there is a transformation from sp3 C–C to sp2 C–C, which greatly affects the tribological property of Cu-doped VCN films, and with the increase of Cu content, the surface roughness and film thickness accordingly increase, and the nano-hardness has a gradual downward trend, however, the average grain size has an unexpected order: VCN-1Cu < VCN-2Cu < VCN-3Cu < VCN. Among these Cu-doped VCN films, the VCN-3Cu film with a higher sp2 C–C content has the lowest friction coefficient, while the VCN-1Cu film with a higher sp3 C–C content and a minimum grain size has the minimum wear rate of (0.36 ± 0.03) × 10−14 m3/N∙m. Anyhow, the wear mechanism of these Cu-doped VCN films are all oxidation wear and adhesive wear.

A Study of Cu Doping Effects in P2‐Na0.75Mn0.6Fe0.2(CuxNi0.2‐x)O2 Layered Cathodes for Sodium‐Ion Batteries

AbstractLayered sodium metal oxide cathodes have much broader choice of transition metal elements than the Li counterparts. A reversible Cu2+/3+ redox couple has recently been introduced in such Na cathodes. To study the role of Cu, here P2‐type layered Na0.75Mn0.6Fe0.2(CuxNi0.2‐x)O2 compounds have been designed, synthesized and investigated. It shows the high initial capacity of 206 mAh/g and good capacity retention. Reversible oxygen redox activity is observed in our experiments. Our DFT calculations suggest that Cu can stabilize the oxygen redox by modifying the electronic structure together with Fe at high voltages. In addition, the strong P′2 transition observed at low voltages is induced by Jahn‐Teller active Cu2+ with two competing effects of enhanced Na ion diffusivity and reduced electronic conductivity.