Enhancing the Lithium Storage Performance of the Nb2O5 Anode via Synergistic Engineering of Phase and Cu Doping

Nb2O5 has been viewed as a promising anode material for lithium-ion batteries by virtue of its appropriate redox potential and high theoretical capacity. However, it suffers from poor electric conductivity and low ion diffusivity. Herein, we demonstrate the controllable fabrication of Cu-doped Nb2O5 with orthorhombic (T-Nb2O5) and monoclinic (H-Nb2O5) phases through annealing the solvothermally presynthesized Nb2O5 precursor under different temperatures in air, and the Cu doping amount can be readily controlled by the concentration of the precursor solution, whose effect on the lithium storage behaviors of the Cu-doped Nb2O5 is thoroughly investigated. H-Nb2O5 shows obvious redox peaks (Nb5+/Nb4+ and Nb4+/Nb3+) with much higher capacity and better cycling stability than those for the widely investigated T-Nb2O5. When introducing appropriate Cu doping, the optimized H-Cu0.1-Nb2O5 electrode shows greatly enhanced conductivity and lower diffusion barrier as revealed by the theoretical calculations and electrochemical characterizations, delivering a high reversible capacity of 203.6 mAh g-1 and a high capacity retention of 140.8 mAh g-1 after 5000 cycles at 1 A g-1, with a high initial Coulombic efficiency of 91% and a high rate capacity of 144.2 mAh g-1 at 4 A g-1. As a demonstration for full-cell application, the H-Cu0.1-Nb2O5||LiFePO4 cell displays good cycling performance, exhibiting a reversible capacity of 135 mAh g-1 after 200 cycles at 0.2 A g-1. More importantly, this work offers a new synthesis protocol of the monoclinic Nb2O5 phase with high capacity retention and improved reaction kinetics.

Fabrication and Characterization of Electrospun Cu-Doped TiO2 Nanofibers and Enhancement of Photocatalytic Performance Depending on Cu Content and Electron Beam Irradiation

Titanium dioxide (TiO₂) is a widely studied material with many attractive properties such as its photocatalytic features. However, its commercial use is limited due to issues such as deactivation in the visible spectrum caused by its wide bandgap and the short lifetime of photo-excited charge carriers. To overcome these challenges, various modifications could be considered. In this study, we investigated copper doping and electron beam treatment. As-spun TiO2 nanofibers were fabricated by electrospinning a TiO2 sol, which obtained viscosity through a polyvinylpyrrolidone (PVP) matrix. Cu-doped TiO2 nanofibers with varying dopant concentrations were synthesized by adding copper salts. Then, the as-spun nanofibers were calcined for crystallization. To evaluate photocatalytic performance, a photodegradation test of methylene blue aqueous solution was performed for 6 h. Methylene blue concentration was measured over time using UV-Vis spectroscopy. The results showed that Cu doping at an appropriate concentration and electron-beam irradiation showed improved photocatalytic efficiency compared to bare TiO2 nanofibers. When the molar ratio of Cu/Ti was 0.05%, photodegradation rate was highest, which was 10.39% higher than that of bare TiO2. As a result of additional electron-beam treatment of this sample, photocatalytic efficiency improved up to 8.93% compared to samples without electron-beam treatment.

Biosurfactant-Assisted Cu Doping of Brushite Coatings: Enhancing Structural, Electrochemical, and Biofunctional Properties

Stainless steel (316L SS) has been widely used in orthopedic, cardiovascular stents, and other biomedical implant applications due to its strength, corrosion resistance, and biocompatibility. To address the weak interaction between steel implants and tissues, it is a widely adopted strategy to enhance implant performance through the application of bioactive coatings. In this study, Cu-doped brushite coatings were deposited successfully through pulse electrodeposition on steel substrates facilitated with a biosurfactant (BS) (i.e., surfactin). Further, the combined effect of various concentrations of Cu ions and BS on the structural, electrochemical, and biological properties was studied. The X-ray diffraction (XRD) confirms brushite composition with Cu substitution causing lattice contraction and a reduced crystallite size. The scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) studies reveal the morphological changes of the coatings with the incorporation of Cu, which is confirmed by X-ray photoelectron spectroscopy (XPS) and elemental mapping. The Fourier transform infrared (FTIR) and Raman spectroscopy confirm the brushite and Cu doping in the coatings, respectively. Increased surface roughness and mechanical properties of Cu-doped coatings were analyzed by using atomic force microscopic (AFM) and nanohardness tests, respectively. Electrochemical assessments demonstrate corrosion resistance enhancement in Cu-doped coatings, which is further improved with the addition of biosurfactants. In vitro biomineralization studies show the Cu-doped coating's potential for osseointegration, with added stability. The cytocompatibility of the coatings was analyzed using live/dead and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays; cell adhesion, proliferation, and migration studies were evaluated using SEM. Antibacterial assays highlight significant improvement in the antibacterial properties of Cu-doped coatings with BS. Thus, the developed Cu-doped brushite coatings with BS demonstrate their potential in the realm of biomedical implant technologies, paving the way for further exploration.

Slow-Released Cationic Redox Activity Promoted Stable Anionic Redox and Suppressed Jahn-Teller Distortion in Layered Sodium Manganese Oxides

Manganese-based layered oxides are considered promising cathodes for sodium ion batteries due to their high capacity and low-cost manganese and sodium resources. Triggering the anionic redox reaction (ARR) can exceed the capacity limitation determined by conventional cationic redox. However, the unstable ARR charge compensation and Jahn-Teller distortion of Mn3+ ions readily result in structural degradation and rapid capacity fade. Here, we report a P2-type Na0.8Li0.2Mn0.7Cu0.1O2 cathode that shows a capacity retention of 84.5% at 200 mA/g after 200 cycles. Combining in situ X-ray diffraction and multi other ex situ characterizations, we reveal that the enhanced cycling stability is ascribed to a slow release of cationic redox activity which can well suppress the Jahn-Teller distortion and favor the ARR reversibility. Furthermore, density-functional theory calculations demonstrate that the inhibited interlayer migration and reduced band gap facilitate the stability and kinetic behavior of ARR. These findings provide a perspective for designing high-energy-density cathode materials with ARR activity.

Electronic Modulation in Cu Doped NiCo LDH/NiCo Heterostructure for Highly Efficient Overall Water Splitting

Layered double hydroxides (LDHs), promising bifunctional electrocatalysts for overall water splitting, are hindered by their poor conductivity and sluggish electrochemical reaction kinetics. Herein, a hierarchical Cu-doped NiCo LDH/NiCo alloy heterostructure with rich oxygen vacancies by electronic modulation is tactfully designed. It extraordinarily effectively drives both the oxygen evolution reaction (151 mV@10 mA cm-2 ) and the hydrogen evolution reaction (73 mV@10 mA cm-2 ) in an alkaline medium. As bifunctional electrodes for overall water splitting, a low cell voltage of 1.51 V at 10 mA cm-2 and remarkable long-term stability for 100 h are achieved. The experimental and theoretical results reveal that Cu doping and NiCo alloy recombination can improve the conductivity and reaction kinetics of NiCo LDH with surface charge redistribution and reduced Gibbs free energy barriers. This work provides a new inspiration for further design and construction of nonprecious metal-based bifunctional electrocatalysts based on electronic structure modulation strategies.

Inkjet-printed SnOx as an effective electron transport layer for planar perovskite solar cells and the effect of Cu doping

Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO2 ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers.

Compositional Engineering of Cu-Doped SnO Film for Complementary Metal Oxide Semiconductor Technology

Metal oxide semiconductor (MOS)-based complementary thin-film transistor (TFT) circuits have broad application prospects in large-scale flexible electronics. To simplify circuit design and increase integration density, basic complementary circuits require both p- and n-channel transistors based on an individual semiconductor. However, until now, no MOSs that can simultaneously show p- and n-type conduction behavior have been reported. Herein, we demonstrate for the first time that Cu-doped SnO (Cu:SnO) with HfO2 capping can be employed for high-performance p- and n-channel TFTs. The interstitial Cu+ can induce an n-doping effect while restraining electron-electron scatterings by removing conduction band minimum degeneracy. As a result, the Cu3 atom %:SnO TFTs exhibit a record high electron mobility of 43.8 cm2 V-1 s-1. Meanwhile, the p-channel devices show an ultrahigh hole mobility of 2.4 cm2 V-1 s-1. Flexible complementary logics are then established, including an inverter, NAND gates, and NOR gates. Impressively, the inverter exhibits an ultrahigh gain of 302.4 and excellent operational stability and bending reliability.

Performance of Fluxgate Magnetometer with Cu-Doped CoFeSiB Amorphous Microwire Core

In this study, we investigated the effects of Cu doping on the performance of CoFeSiB amorphous microwires as the core of a fluxgate magnetometer. The noise performance of fluxgate sensors primarily depends on the crystal structure of constituent materials. CoFeSiB amorphous microwires with varying Cu doping ratios were prepared using melt-extraction technology. The microstructure of microwire configurations was observed using transmission electron microscopy, and the growth of nanocrystalline was examined. Additionally, the magnetic performance of the microwire and the noise of the magnetic fluxgate sensors were tested to establish the relationship between Cu-doped CoFeSiB amorphous wires and sensor noise performance. The results indicated that Cu doping triggers a positive mixing enthalpy and the reduced difference in the atomic radius that enhances the degree of nanocrystalline formation within the system; differential scanning calorimetry analysis indicates that this is due to Cu doping reducing the glass formation capacity of the system. In addition, Cu doping affects the soft magnetic properties of amorphous microwires, with 1% low-doping samples exhibiting better soft magnetic properties. This phenomenon is likely the result of the interaction between nanocrystalline organization and magnetic domains. Furthermore, a Cu doping ratio of 1% yields the best noise performance, aligning with the trend observed in the material's magnetic properties. Therefore, to reduce the noise of the CoFeSiB amorphous wire sensor, the primary goal should be to reduce microscopic defects in amorphous alloys and enhance soft magnetic properties. Cu doping is a superior preparation method which facilitates control over preparation conditions, ensuring the formation of stable amorphous wires with consistent performance.

Highly Active and Water-Resistant Cu-Doped OMS-2 Catalysts for CO Oxidation: The Importance of the OMS-2 Synthesis Method and Cu Doping

Porous cryptomelane-type Mn oxide (OMS-2) has an outstanding redox property, making it a highly desirable substitute for noble metal catalysts for CO oxidation, but its catalytic activity still needs to be improved, especially in the presence of water. Given the strong structure-performance correlation of OMS-2 for oxidation reactions, herein, OMS-2 is synthesized by solid state (OMS-2S), reflux (OMS-2R), and hydrothermal (OMS-2H) methods, aiming to improve its CO oxidation performance through manipulating synthesis parameters to tailor its particle size, morphology, and crystallinity. Characterization shows that OMS-2S has the highest CO oxidation activity in the absence of water due to its low crystallinity, high specific surface area, large oxygen vacancy content, and good redox property, but the presence of water can greatly reduce its CO oxidation activity. Doping Cu into an OMS-2 can not only improve its CO oxidation activity but also greatly improve its water tolerance. The Cu-doped OMS-2S catalyst with ∼4 wt % Cu can achieve a T90 of 49 °C (1% CO/10% O2/N2 and WHSV = 60,000 mL·g-1·h-1), ranking among the lowest reported T90 values for Mn oxide-based CO oxidation catalysts, and it can maintain nearly 100% CO conversion in the presence of 5 vol % water for over 50 h. In situ DRIFTs characterization indicates that the good water resistance of Cu-doped OMS-2S can be attributed to the significantly suppressed surface hydroxyl group generation because of Cu doping. This work demonstrates the importance of the synthesis method and Cu doping in determining the CO oxidation activity and water resistance of OMS-2 and will provide guidance for synthesizing highly active and water-resistant CO oxidation catalysts.

In-situ-grown multidimensional Cu-doped Co1-xS2@MoS2 on N-doped carbon nanofibers as anode materials for high-performance alkali metal ion batteries

Transition metal sulfides with the high theoretical capacity and low cost have been considered as advanced anode candidate for alkali metal ion batteries, but suffered from unsatisfactory electrical conductivity and huge volume expansion. Herein, a multidimensional structure Cu-doped Co1-xS2@MoS2 in-situ-grown on N-doped carbon nanofibers (denoted as Cu-Co1-xS2@MoS2 NCNFs) have been elaborately constructed for the first time. The bimetallic zeolitic imidazolate framework CuCo-ZIFs were encapsulated in the one-dimensional (1D) NCNFs through an electrospinning route and then on which the two-dimensional (2D) MoS2 nanosheets were in-situ grown via a hydrothermal process. The architecture of 1D NCNFs can effectively shorten ion diffusion path and enhance electrical conductivity. Besides, the formed heterointerface between MOF-derived binary metal sulfides and MoS2 can provide extra active centers and accelerate reaction kinetics, which guarantee a superior reversibility. As expected, the resulting Cu-Co1-xS2@MoS2 NCNFs electrode delivers excellent specific capacity of Na-ion batteries (845.6 mAh/g at 0.1 A/g), Li-ion batteries (1145.7 mAh/g at 0.1 A/g), and K-ion batteries (474.3 mAh/g at 0.1 A/g). Therefore, this innovative design strategy will bring a meaningful prospect for developing high-performance multi-component metal sulfides electrode for alkali metal ion batteries.

One-Pot Synthesis of Lamellar Fe-Cu Bimetal-Decorated Reduced Graphene Oxide and Its Enhanced Removal of Cr(VI) from Water

Hexavalent chromium (Cr(VI)) is a typical heavy metal pollutant, making its removal from wastewater imperative. Although nanosized zero-valent iron (nZVI) and graphene-based materials are excellent remediation materials, they have drawbacks, such as agglomeration and being difficult to recycle. A facile synthesis method for decorating reduced graphene oxide (rGO) with ultrathin nZVI (within 10 nm) was explored in this study in order to develop an effective tool for Cr(VI) detoxication. Cu particles were doped in these composites for electron-transfer enhancement and were verified to improve the rate by 2.4~3.4 times. Batch experiments were conducted at different pHs, initial concentrations, ionic strengths, and humic acid (HA) concentrations. From these observations, it was found that the acid condition and appearance of Cu and rGO enhanced the treatment capacity. This procedure was fitted with a pseudo-second-order model, and the existence of NaCl and HA impeded it to some extent. Cr(VI) could be detoxified into Cr(III) and precipitated on the surface. Combining these analyses, a kinetics study, and the characterizations before and after the reaction, the removal mechanism of Cr(VI) was further discussed as a complex process involving adsorption, reduction, and precipitation. The maximum removal capacity of 156.25 mg g-1 occurred in the acid condition, providing a potential Cr(VI) remediation method.

Study on the Degradation of Methylene Blue by Cu-Doped SnSe

Treatment of organic wastewater is still a difficult problem to solve. In this paper, Cu-doped SnSe powder was synthesized by a convenient and efficient hydrothermal method. Meanwhile, the degradation effect of different doping concentrations of SnSe on methylene blue was investigated. It was found that at low doping concentrations, the degradation effect on methylene blue was not obvious because Cu was dissolved in the lattice of the SnSe matrix at low concentrations. As the doping concentration increased, SnSe changed from a layered structure to a nanocluster structure with reduced particle size, and a mixed phase of SnSe and Cu2SnSe4 appeared. In fact, the degradation effect on methylene blue was significantly enhanced, and we found that the catalytic degradation effect on methylene blue was best at a doping concentration of 10 wt.%.

Activation of Co-O bond in (110) facet exposed Co3O4 by Cu doping for the boost of propane catalytic oxidation

Defects engineering in metal oxide is an important avenue for the promotion of VOCs catalytic oxidation. Herein, the influence of crystal facet of Co₃O₄ is first investigated for the propane oxidation. An intelligent Cu doping is subsequently performed in the most active (110) facet exposed Co₃O₄ catalyst. The optimized Cu-Co₃O₄-110-3 catalyst exhibits a prominently enhanced activity with propane conversion rate of 1.9 μmol g^-1 s^-1 at reaction temperature of 192 °C and the propane mass space velocity of 60,000 mL g^-1 h^-1, about 2.4 times that of the pristine Co₃O₄. Systematic experimental characterizations (XAS, EPR, Raman, TPR, XPS, etc.) combined with density functional theory calculations point out that the incorporated Cu could increase the electrophilicity of nearby O atom and implant beneficial defect structures (lattice distortion, coordination unsaturation, abundant oxygen vacancies, etc.), which could significantly activate Co-O bond in Co₃O₄, leading to the facilitated generation of active oxygen species as well as promoted oxidation ability. This study could set an illuminating paradigm for the boost of the intrinsic oxidation activity by the precise defect construction in Co₃O₄ catalyst, which will help drive ahead the pursuit of non-precious metal catalyst for VOCs abatement.

Design of Cu-substituted O3-type NaFe0.5Mn0.5O2 Cathode Materials for Sodium-ion Batteries

O3-type Fe/Mn-based layered oxide cathode materials with abundant reserves have a promising prospect in sodium-ion batteries. However, the electrochemical reversibility of most O3-type Fe/Mn-based oxide cathode materials is still not high enough. Herein, the effect of different Cu contents on the electrochemical properties of O3-NaFe0.50Mn0.50O2 materials is systematically investigated. The as-prepared NaFe0.30Mn0.50Cu0.20O2 cathode achieves the synergistic optimization of the interface and bulk phase, and showes superior electrochemical performance, with an initial discharge specific capacity of 114 mAh g-1 at 0.1 C, a capacity retention rate of 94% after 100 cycles at 0.5 C, and excellent chemical stability in air and water. In addition, the sodium ion full battery based on NaFe0.30Mn0.50Cu0.20O2 cathode and hard carbon anode has a capacity retention rate of 81% after 100 cycles. This research provides a useful approach for the preparation of low-cost and high-performance O3-type layered cathode materials.

One-step fabrication of Cu-doped Bi2MoO6 microflower for enhancing performance in photocatalytic nitrogen fixation

This study enhances the photocatalytic N₂ immobilization performance of Bi₂MoO₆ through Cu doping. Cu-doped Bi₂MoO₆ was synthesized via a simple solvothermal method. Various characterizations were implemented to examine the influence of Cu doping on the properties of Bi₂MoO₆. Results indicated that the doped Cu element had a valence state of + 2 and substituted the position of Bi³⁺. Cu doping exerted minimal effect on the morphology of Bi₂MoO₆ but largely influenced the energy band structure. The band gap was slightly narrowed, and the conduction band was raised, such that Cu-doped Bi₂MoO₆ could generate more electrons with stronger reducibility. Moreover, importantly, Cu doping reduced work function and improved charge separation efficiency, which was considered the major cause of enhanced photoactivity. In addition, the Cu-Bi₂MoO₆ catalyst exhibited higher capability in the adsorption and activation of N₂. Under the combined effects of the aforementioned changes, Cu-Bi₂MoO₆ demonstrated considerably higher photocatalytic efficiency than Bi₂MoO₆. The optimized NH₃ generation rate reached 302 μmol/L g^-1h^-1 and 157 μmol/L g^-1h^-1 under simulated solar light and visible light, respectively, both achieving about 2.2 times higher than that of Bi₂MoO₆. This work provides a successful example of improving photocatalytic N₂ fixation, and it may show some light on the design and preparation of heteroatom-doped semiconductor photocatalysts for N₂-to-NH₃ conversion.

Functional Regulation of ZnAl-LDHs and Mechanism of Photocatalytic Reduction of CO2: A DFT Study

Defect engineering and heteroatom doping can significantly enhance the activity of zinc-aluminum layered double hydroxides (ZnAl-LDHs) in photocatalytic CO₂ reduction to fuel. However, the in-depth understanding of the associated intrinsic mechanisms is limited. Herein, we systematically investigated Zn vacancies (V_Zn), oxygen vacancies (V_O), and Cu doping on the geometry and electronic structure of ZnAl-LDH using density functional theory (DFT). We also revealed the related reaction mechanism. The results reveal the concerted roles of V_O, V_Zn, and doped-Cu facilitate the formation of the unsaturated metal complexes (Zn^δ+-V_O and Cu^δ+-V_O). They can localize the charge density distribution, function as new active centers, and form the intermediate band. Simultaneously, the intermediate band of functionalized ZnAl-LDHs narrows the band gap and lowers the band edge location. Therefore, it can broaden the absorption range of light and improve the selectivity of CO. Additionally, the unsaturated metal complex lowers the Gibbs free energy barrier for effective CO₂ activation by bringing the d-band center level closer to the Fermi level. The work provided guidance for developing LDH photocatalysts with high activity and selectivity.

Exploring Cu-Doping for Performance Improvement in Sb2Se3 Photovoltaic Solar Cells

Copper-doped antimony selenide (Cu-doped Sb2Se3) thin films were deposited as absorber layers in photovoltaic solar cells using the low-temperature pulsed electron deposition (LT-PED) technique, starting from Sb2Se3 targets where part of the Sb was replaced with Cu. From a crystalline point of view, the best results were achieved for thin films with about Sb1.75Cu0.25Se3 composition. In order to compare the results with those previously obtained on undoped thin films, Cu-doped Sb2Se3 films were deposited both on Mo- and Fluorine-doped Tin Oxide (FTO) substrates, which have different influences on the film crystallization and grain orientation. From the current-voltage analysis it was determined that the introduction of Cu in the Sb2Se3 absorber enhanced the open circuit voltage (VOC) up to remarkable values higher than 500 mV, while the free carrier density became two orders of magnitude higher than in pure Sb2Se3-based solar cells.

Synergistic Modification of Fe-Based Prussian Blue Cathode Material Based on Structural Regulation and Surface Engineering

The Fe-based Prussian blue (Fe-PB) composite is considered as one of the most potential cathode materials for sodium-ion batteries because of its abundant iron resources and high theoretical capacity. However, the crystal water and vacancy in the Fe-PB structure will lead to poor capacity and cycle stability. In this work, a Cu-modified Fe-PB composite (FeCu-PB@CuO) is successfully prepared through regulating the Fe-PB structure by Cu doping and engineering the surface by CuO coating. The density functional theory calculation results confirm that Cu preferentially replaces Fe^HS in the Fe-PB lattice and Cu doping reduces the bandgap. Our experiment results reveal that CuO coating can provide more active sites, inhibit side reactions, and potentially enhance the activity of Fe^HS. Due to the synergistic effect of Cu doping and CuO coating, FeCu-PB@CuO has a considerable initial discharge capacity of 123.5 mAh g^-1 at 0.1 A g^-1. In particular, at 2 A g^-1, it delivers an impressive initial capacity of 84.3 mAh g^-1, and the capacity decreasing rate of each cycle is only 0.02% over 1500 cycles. Therefore, the synergistic modification strategy of metal ion doping and metal oxide coating has tremendous application potential and can be extended to other electrode materials.

Hybrid Density Functional Investigation of Cu Doping Impact on the Electronic Structures and Optical Characteristics of TiO2 for Improved Visible Light Absorption

We report a theoretical investigation of the influence of Cu doping into TiO₂ with various concentrations on crystal structure, stability, electronic structures and optical absorption coefficient using density functional theory via the hybrid formalism based on Heyd Scuseria Ernzerhof. Our findings show that oxygen-rich environments are better for fabricating Cu-doped materials and that the energy of formation for Cu doping at the Ti site is lower than for Cu doping at the O site under these environments. It is found that Cu doping introduces intermediate bands into TiO₂, narrowing the band gap. Optical absorption curves show that the Cu-doped TiO₂ can successfully harvest visible light. The presence of widely intermediate bands above the valence-band edge could explain the increase in the visible light absorption range. However, the intensity of visible light absorption rises with the increase in doping concentration.

High-Performance Fe-Based Prussian Blue Cathode Material for Enhancing the Activity of Low-Spin Fe by Cu Doping

Iron-based Prussian blue (FeHCF) has great application potential in the large-scale production of sodium-ion (Na⁺) batteries because of its high theoretical capacity and abundant Fe ore resources. However, the Fe(CN)₆ vacancies and crystal water seriously affect the electrochemical performance. Herein, a Cu-doped FeHCF (Cu-FeHCF) cathode material is successfully prepared directly by a coprecipitation method. After Cu doping, the monoclinic structure and the quasi-cubic morphology are retained, but the electrochemical performance is significantly improved. In addition to few Fe(CN)₆ vacancies and low crystal water, the improved performance is also related to the enhanced electrochemical activity of low-spin Fe and the stabilizing effect of Cu on the crystal structure. Moreover, Cu doping also controls the side reaction to a certain extent. As a result, after Cu doping, the initial discharge capacity is enhanced from 107.9 to 127.4 mA h g^-1 at 100 mA g^-1, especially the capacities contributed by low-spin Fe increase from 30.0, 21.7, and 16.7 mA h g^-1 to 48.8, 45.4, and 43.7 mA h g^-1 for the first three cycles, respectively. Even at 2 A g^-1, Cu-FeHCF still has a promising initial capacity of 82.3 mA h g^-1 and only a 0.047% capacity decay rate for each cycle over 500 cycles. Therefore, Cu-FeHCF shows excellent application potential in the field of Na⁺ energy storage batteries.

Understanding the roles of copper dopant and oxygen vacancy in promoting nitrogen oxides removal over iron-based catalyst surface: A collaborative experimental and first-principles study

In this work, we proposed a novel strategy of copper (Cu) doping to enhance the nitrogen oxides (NO_x) removal efficiency of iron (Fe)-based catalysts at low temperature through a simple citric acid mixing method, which is critical for its practical application. The doping of Cu significantly improves the deNO_x performance of Fe-based catalysts below 200 °C, and the optimal catalyst is (Cu_0.22Fe_1.78)_1-δO₃, which deNO_x efficiency can reach 100% at 160-240 °C. From the macro aspects, the main reasons for the excellent catalytic activity of the (Cu_0.22Fe_1.78)_1-δO₃ catalyst are the large number of oxygen vacancies (O_vac), appropriate Fe³⁺ and Cu²⁺ contents, stronger surface acidity and redox ability. From the micro aspects, the O_vac plays a key role in enhancing molecular adsorption, oxidation, and the deNO_x reaction over the Fe-based catalyst surface, which promoting order is CuO_vac > O_vac > Cu. This work provides a new insight for the mechanism study of oxygen vacancy engineering and also accelerates the development of CuFe bimetal composite catalysts at low temperature.

Isotropic Thermoelectric Performance of Layer-Structured n-Type Bi2Te2.7Se0.3 by Cu Doping

The lamellar structure of (Bi,Sb)₂(Te,Se)₃ alloys makes it difficult to achieve isotropic thermoelectric properties in the directions along and perpendicular to the c-axis, especially for n-type samples. In this work, by introducing Cu in polycrystalline n-type Cu_xBi₂Te_2.7Se_0.3 and applying the traditional synthesis process of high-energy ball milling and hot pressing, substantial enhancement of the thermoelectric figure of merit zT is obtained in both in-plane and out-of-plane directions. The intercalated Cu not only provides electron transport media for mobility improvement but also reduces the lattice thermal conductivity owing to the strain fluctuation. Typically, the van der Waals gap in the out-of-plane direction leads to relatively slower mobility and lower lattice thermal conductivity. Taking into account the same average density-of-state effective mass (m_avg^* ∼ 1.5m_e) predicted based on a single parabolic model, the obtained quality factor β is comparable in both directions. As a result, a peak zT ∼ 1.05 at 420 K and the average zT approaching to 1.0 in the temperature range 300-500 K are obtained in both directions for the Cu_0. 02Bi₂Te_2.7Se_0.3 sample. The simple synthesis process and isotropic thermoelectric properties in this work make n-type Bi₂Te₃ more convenient for potential production and application.

Copper-Stabilized P'2-Type Layered Manganese Oxide Cathodes for High-Performance Sodium-Ion Batteries

Layered sodium manganese oxides are promising low-cost and high-capacity cathode materials for commercialization of sodium-ion batteries (SIBs). P'2-type Na_0.67MnO₂ with an orthorhombic structure has been considered as a significant candidate for SIBs. However, the Jahn-Teller distortion and undesired phase transitions will lead to poor structural stability and unsatisfactory cycling performance. Herein, a systematic investigation on partially copper-doped P'2-type Na_0.67Cu_xMn_1-xO₂ (x = 0, 0.05, 0.1, and 0.2) series as cathodes for SIBs reveals the relationship between doping concentrations and Na storage properties. With proper copper content, P'2 Na_0.67Cu_0.1Mn_0.9O₂ exhibits a suppressed Jahn-Teller effect as well as relatively less phase transitions, which can deliver a high specific capacity of 222.7 mA h g^-1 at 10 mA g^-1 within 1.5-4.2 V, with a capacity retention of 76% at 1 A g^-1 after 300 cycles. The electrochemical mechanism is systematically investigated via in situ X-ray diffraction observations and density functional theory calculations, which provide fundamental guidelines for developing high-performance cathodes for SIBs.

Efficient photodegradation of azucryl red by copper-doped TiO2 nanoparticles-experimental and modeling studies

This research aims to investigate the effect of copper doping on the photocatalysis performance of TiO₂ nanoparticles for disposal wastewater from organic pollutants. X-ray diffraction analysis manifests the crystallization of a rutile phase for pure and copper-doped TiO₂ except for 2% resulting in a rutile-to-anatase phase transformation. The crystallite size is found less affected by Cu doping, i.e., ~30 nm. BET analysis indicates a decrease in the specific surface area as the doping loading increases. Scanning electron microscopy observations reveal spherical particles at the nanometer range for pure TiO₂ and then larger agglomerates of ultrafine particles with Cu doping. FTIR analysis notifies the existence of hydroxyl groups, which will promote the photocatalysis process. The photodegradation of azucryl red (AR) has been investigated under different conditions; i.e., Cu-loading, initial concentration of AR, and pH. The kinetics of the photodegradation process is further found to comply with the Lagergren kinetic law, regardless the experimental conditions. Nevertheless, the photodegradation process is not only controlled by the intra-particle diffusion mechanism, but also by mass transfer through a liquid film boundary. The maximum degradation of AR, i.e., 86%, has been achieved at pH = 5.0 during 60 min of contact time for the 2% Cu doping, with effective regeneration. The Freundlich model exhibits a better fitting for AR dye photodegradation equilibrium data, compared to Langmuir, Temkin, and Dubinin-Radushkevich.

Cu Doping-Induced Transformation from [Ag62 S12 (SBut )32 ]2+ to [Ag62-x Cux S12 (SBut )32 ]4+ Nanocluster

The change in the valence state of nanocluster can induce remarkable changes in the properties and structure. However, achieving the valence state changes in nanoclusters is still a challenge. In this work, we use Cu²⁺ as dopant to "oxidize" [Ag₆₂ S₁₂ (SBu^t )₃₂ ]²⁺ (4 free electrons) to obtain the new nanocluster: [Ag_62-x Cu_x S₁₂ (SBu^t )₃₂ ]⁴⁺ with 2 free electrons. As revealed by its structure, the [Ag_62-x Cu_x S₁₂ (SBu^t )₃₂ ]⁴⁺ (x=10∼21) has a similar structure to that of [Ag₆₂ S₁₂ (SBu^t )₃₂ ]²⁺ precursor and all the Cu atoms occupy the surface site of nanocluster. It's worth noting that with the Cu atoms doping, the [Ag_62-x Cu_x S₁₂ (SBu^t )₃₂ ]⁴⁺ nanocluster is more stable than [Ag₆₂ S₁₂ (SBu^t )₃₂ ]²⁺ at higher temperature and in electrochemical cycle. This result has laid a foundation for the subsequent application and exploration. Overall, this work reveals crystals structure of a new Ag-Cu nanocluster and offers a new insight into the electron reduction/oxidation of nanocluster.

Effects of Cu Precursor on the Performance of Efficient CdTe Solar Cells

Copper (Cu) incorporation is a key process for fabricating efficient CdTe-based thin-film solar cells and has been used in CdTe-based solar cell module manufacturing. Here, we investigate the effects of different Cu precursors on the performance of CdTe-based thin-film solar cells by incorporating Cu using a metallic Cu source (evaporated Cu) and ionic Cu sources (solution-processed cuprous chloride (CuCl) and copper chloride (CuCl₂)). We find that ionic Cu precursors offer much better control in Cu diffusion than the metallic Cu precursor, producing better front junction quality, lower back-barrier heights, and better bulk defect property. Finally, outperforming power conversion efficiencies of 17.2 and 17.5% are obtained for devices with cadmium sulfide and zinc magnesium oxide as the front window layers, respectively, which are among the highest reported CdTe solar cells efficiencies. Our results suggest that an ionic Cu precursor is preferred as the dopant to fabricate efficient CdTe thin-film solar cells and modules.

Enhanced heterogeneous Fenton-like degradation of refractory organic contaminants over Cu doped (Mg,Ni)(Fe,Al)2O4 synthesized from laterite nickel ore

The heterogeneous Fenton-like catalyst (Mg,Cu,Ni)(Fe,Al)₂O₄ was synthesized via a coprecipitation method using laterite nickel ore leaching solution as raw material. The effects of CuCl₂·2H₂O addition and calcination temperature on the microstructures and degradation properties of the obtained products were investigated. Results showed that higher calcination temperature could promote the migration of Cu²⁺ ions from CuO to the spinel ferrite lattice and occupied octahedral sites. The degradation efficiencies (η) of various types of low-concentration dyes and tetracycline were higher than 95%, which was mainly due to the accelerated generation of OH radicals by the synergistic effect of Fe³⁺ and Cu²⁺ ions in octahedral sites of the formed (Mg,Cu,Ni)(Fe,Al)₂O₄. Moreover, after five consecutive degradation cycles, the η of RhB was still close to 100%, TOC removal efficiency was maintained around 40% and the concentrations of metallic ions in degraded solutions were all lower than the national effluent discharge standard (GB8978-1996), confirming the as-obtained (Mg,Cu,Ni)(Fe,Al)₂O₄ was an eco-friendly heterogeneous Fenton-like catalyst with excellent stability and reusability. This study may provide an effective reference for large scale preparing efficient heterogeneous Fenton-like catalysts from natural minerals in treating the wastewater contaminated by refractory organics.

Cu-Doped ZnO Nanoparticles for Non-Enzymatic Glucose Sensing

Copper-doped zinc oxide nanoparticles (NPs) CuxZn1-xO (x = 0, 0.01, 0.02, 0.03, and 0.04) were synthesized via a sol-gel process and used as an active electrode material to fabricate a non-enzymatic electrochemical sensor for the detection of glucose. Their structure, composition, and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) and Raman spectroscopies, and zeta potential measurements. The electrochemical characterization of the sensors was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Cu doping was shown to improve the electrocatalytic activity for the oxidation of glucose, which resulted from the accelerated electron transfer and greatly improved electrochemical conductivity. The experimental conditions for the detection of glucose were optimized: a linear dependence between the glucose concentration and current intensity was established in the range from 1 nM to 100 μM with a limit of detection of 0.7 nM. The proposed sensor exhibited high selectivity for glucose in the presence of various interfering species. The developed sensor was also successfully tested for the detection of glucose in human serum samples.

Surface Properties of 1DTiO2 Microrods Modified with Copper (Cu) and Nanocavities

This work deals with Cu-modified 1DTiO2 microrods (MRs) and their surface properties. The pristine lyophilized precursor Cu_1DTiO2, prepared by an environmentally friendly cryo-lyophilization method, was further annealed in the temperature interval from 500 to 950 °C. The microstructure of all samples was characterized by electron microscopy (SEM/EDS and HRTEM/SAED), X-ray powder diffraction (XRD), infrared spectroscopy, simultaneous DTA/TGA thermoanalytical measurement, and mass spectroscopy (MS). Special attention was paid to the surface structure and porosity. The 1D morphology of all annealed samples was preserved, but their surface roughness varied due to anatase-rutile phase transformation and the change of the nanocrystals habits due to nanocavities formation after releasing of confined ice-water. The introduction of 2 wt.% Cu as electronically active second species significantly reduced the direct bandgap of 1DTiO2 in comparison with undoped TiO2 and the standard Degussa TiO2_P25. All samples were tested for their UV absorption properties and H2 generation by PEC water splitting. We presented a detailed study on the surface characteristics of Cu doped 1DTiO2 MRs due to gain a better idea of their photocatalytic activity.

Identifying the Origin of Ti3+ Activity toward Enhanced Electrocatalytic N2 Reduction over TiO2 Nanoparticles Modulated by Mixed-Valent Copper

The ambient electrocatalytic N₂ reduction reaction (NRR) enabled by TiO₂ has attracted extensive recent attention. Previous studies suggest the formation of Ti³⁺ in TiO₂ can significantly improve the NRR activity, but it still remains unclear what kinds of Ti³⁺ are effective. Herein, it is demonstrated that mixed-valent Cu acts as an effective dopant to modulate the oxygen vacancy (V_O ) concentration and Ti³⁺ formation, which markedly improves the electrocatalytic NRR performance. In 0.5 m LiClO₄ , this electrocatalyst attains a high Faradic efficiency of 21.99% and a large NH₃ yield of 21.31 µg h^-1 mg_cat. ^-1 at -0.55 V vs reversible hydrogen electrode, which even surpasses most reported Ti-based NRR electrocatalysts. Using density function theory calculations, it is evidenced that mixed-valent Cu ions modulate the TiO₂ (101) surface with multiple oxygen vacancies, which is beneficial for generating different Ti³⁺ 3d¹ defect states localized below the Fermi energy. N₂ activation and adsorption are effectively strengthened when Ti³⁺ 3d¹ defect states present the splitting of e_g and t_2g orbitals, which can be modulated by its coordination structure. The synergistic roles of the three ion pairs formed by the V_O defect, including Cu¹⁺ -Ti⁴⁺ , Ti³⁺ -Ti⁴⁺ and Ti³⁺ -Ti³⁺ , are together responsible for the enhanced NRR performance.

Tuning oxygen vacancy concentration of MnO2 through metal doping for improved toluene oxidation

Oxygen vacancy acts an important role in adjusting the chemical properties of MnO₂. In this paper, two-dimensional MnO₂ catalysts with different oxygen vacancy concentration are obtained by doping Cu²⁺. It is researched that the K⁺ species in the interlayer of birnessite-type MnO₂ can be substituted during the Cu²⁺ doping process. Meanwhile, this process will generate the oxygen vacancy. Interestingly, the formation of an appropriate numbers of oxygen vacancy in MnO₂ distinctly enhances the low-temperature reducibility and oxygen species activity, which improves the catalytic activity for the toluene oxidation (T₁₀₀ = 220 °C, E_a=43.6 kJ/mol). However, an excessive concentration of oxygen vacancy in MnO₂ sample performs against the activity improvement for toluene oxidation. In situ DRIFTS are applied to elucidate the main intermediates and conversion pathway on MnO₂-OV3 with moderate concentration of oxygen vacancy. The results demonstrate that the adsorbed toluene can interact with oxygen species of catalyst to form physisorbed benzaldehyde, aldehydic adsorbate and benzoate species. In addition, it is found that the oxygen vacancy concentration plays an important effect on the oxidation of benzoate species owing to the acceleration effect of oxygen vacancy in the activation of gaseous oxygen.

Emission Enhancement of Cu-Doped InP Quantum Dots through Double Shelling Scheme

The doping of transition metal ions, such as Cu⁺ and Mn²⁺ into a quantum dot (QD) host is one of the useful strategies in tuning its photoluminescence (PL). This study reports on a two-step synthesis of Cu-doped InP QDs double-shelled with ZnSe inner shell/ZnS outer shell. As a consequence of the double shelling-associated effective surface passivation along with optimal doping concentrations, Cu-doped InP/ZnSe/ZnS (InP:Cu/ZnSe/ZnS) QDs yield single Cu dopant-related emissions with high PL quantum yields of 57–58%. This study further attempted to tune PL of Cu-doped QDs through the variation of InP core size, which was implemented by adopting different types of Zn halide used in core synthesis. As the first application of doped InP QDs as electroluminescent (EL) emitters, two representative InP:Cu/ZnSe/ZnS QDs with different Cu concentrations were then employed as active emitting layers of all-solution-processed, multilayered QD-light-emitting diodes (QLEDs) with the state-of-the-art hybrid combination of organic hole transport layer plus inorganic electron transport layers. The EL performances, such as luminance and efficiencies of the resulting QLEDs with different Cu doping concentrations, were compared and discussed.

Cu-doped quantum dots: a new class of near-infrared emitting fluorophores for bioanalysis and bioimaging

Transition metal ion-doped quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over undoped QDs, such as larger Stokes shift to avoid self-absorption/energy transfer, longer excited-state lifetimes, wider spectral window, and improved chemical and thermal stability. Among the doped QDs emitters, Cu is widely introduced into the doped QDs as novel, efficient, stable, and tunable optical materials that span a wide spectrum from blue to near-infrared (NIR) light. Their unique physical and chemical characteristics enable the use of Cu-doped QDs as NIR labels for bioanalysis and bioimaging. In this review, we discuss doping mechanisms and optical properties of Cu-doped QDs that are capable of NIR emission. Applications of Cu-doped QDs in in vitro biosensing and in in vivo bioimaging are highlighted. Moreover, a prospect of the future of Cu-doped QDs for bioanalysis and bioimaging are also summarized.

Enhanced catalytic ozonation towards oxalic acid degradation over novel copper doped manganese oxide octahedral molecular sieves nanorods

A series of copper doped manganese oxide octahedral molecular sieves (Cu-OMS_x-T) with different Cu/Mn ratios and hydrothermal temperatures were successfully synthesized and used for catalytic ozonation towards oxalic acid (OA) degradation. The as-prepared Cu-OMS_x-T composites were comprehensively investigated by BET, FT-IR, XPS and etc. characterizations. The results indicated that the Cu doping would increase the specific surface area, change chemical bonds, and promote the transformation of multivalent metals and the generation of oxygen vacancies. It was noteworthy that the hydrothermal temperature played an important role in the morphology of Cu-OMS_x-T composites and the Cu/Mn molar ratios greatly influenced the catalytic activities. Amongst, the Cu-OMS_0.5-140 achieved the optimum catalytic activity with 97.3% of OA degradation efficiency and 98.8% of mineralization rate in 30 min at pH 6.0. Moreover, hydroxyl radical and superoxide radical were identified as the major reactive radicals and the catalytic mechanism for OA degradation enhancement was also elucidated. In addition, the Cu-OMS_0.5-140 exhibited great stability and reusability with high OA mineralization rate (>90%) and low metal release after five times recycle. Overall, the results indicated that the synthesized Cu-OMS_0.5-140 is an efficient, stable, and recyclable ozonation catalyst, and could be a promising alternative material for water purification.

Promotional effect of doping Cu into cerium-titanium binary oxides catalyst for deep oxidation of gaseous dichloromethane

In recent years, significant effort has been made in the development of novel catalysts for the total oxidation of chlorinated volatile organic compounds. In this work the catalytic activity of Cu doped cerium-titanium binary oxides for the oxidation of dichloromethane (DCM) have been studied for the first time. Combining catalysts characterization and activity data, it was found that Cu ions can uniformly disperse into titanium dioxide to form solid solution and induce the creation of additional surface oxygen species on the catalysts surface, while moderate amount of Ce ions are still needed for the activation of CCl. Detailed analysis of the in-situ FTIR experiment results revealed that the surface oxygen species, especially the hydroxyl groups associated with Cu ions, can promote the deep oxidation of the intermediate species formed in the nucleophilic substitution process occurred on the active sites of catalysts surface. The sample with the Cu/Ce molar ratio of 1:3 obtained a better CO₂ selectivity than that reached with cerium-titanium binary oxides. Meanwhile, according to element balance analysis, removal of chlorine from the catalyst surface was also promoted by Cu doping.

Enhanced oxidation potential of Ti/SnO2-Cu electrode for electrochemical degradation of low-concentration ceftazidime in aqueous solution: Performance and degradation pathway

In order to develop an efficient electrode to remove pharmaceutical and personal care products from wastewater, copper and antimony doped Ti/SnO₂ electrode were prepared by thermal decomposition. Electrochemical characterization was undertaken on Ti/SnO₂-Cu using cyclic voltammetry and linear sweep voltammetry, indicating an ultra-high 2.1 V of oxygen evolution potential, better stability, and superior corrosion resistance rather than traditional Ti/SnO₂-Sb electrode. Competitive degradation experiments showed more efficient removal rate was achieved on Ti/SnO₂-Cu electrode, which could remove more than 90% ceftazidime within 60 min. The microstructure and crystal orientation of the modified electrodes were investigated by scanning electron microscopy, which indicated that the crystal of the Ti/SnO₂-Cu electrode grew in more porous and uniform condition, covered with closely arranged layers of the coating. X-ray photoelectron spectroscopy and X-ray diffractions suggested that Cu₂O was successfully coated on the Ti/SnO₂-Cu electrode surface. The operating parameters of electrochemical degradation process were also investigated, including current density, initial concentration, electrode distance, stirring rate and supporting electrolyte. Consequently, the intermediate products of electrochemical degradation were monitored by liquid chromatography-mass spectrometry and a major degradation pathway was proposed.

Enhanced peroxymonosulfate activation for phenol degradation over MnO2 at pH 3.5-9.0 via Cu(II) substitution

Cu(II) doped mesoporous MnO₂ (Cu-MnO₂) was prepared to establish an intimate functional link between the structure substitution and catalytic peroxymonosulfate (PMS) activation. Based on the characterization of powder X-ray diffraction (XRD), N₂ adsorption-desorption measurement, scanning electron microscope (FE-SEM) and transmission electron microscope (TEM), Cu-MnO₂ had a typical long range ordered mesoporous structure and Cu was successfully introduced in octahedral framework. It exhibited excellent catalytic activity and stability for the phenol degradation by PMS. Phenol was always efficiently degraded over Cu-MnO₂ at a pH range of 3.5-9.0. For example, the reaction rate constant at pH 7.0 was 0.073 min^-1, which was two times higher than that of MnO₂ (0.039 min^-1). Importantly, ¹O₂ was identified as the primary reactive species in Cu-MnO₂/PMS system. X-ray photoelectron spectroscopy (XPS) confirmed that more exposed surface oxygen defects due to Cu doping were responsible to the enhancement of PMS activation for phenol degradation. The results of PMS decomposition and oxygen evolution indicated that surface oxygen defects lower the reaction energy barrier of PMS decomposition by generating ¹O₂ via the energy trapping by oxygen. Finally, the heterogeneous PMS activation mechanism over Cu-MnO₂ was proposed.

Study on the copper(II)-doped MIL-101(Cr) and its performance in VOCs adsorption

The metal-organic framework (MOF) materials, MIL-101(Cr), and copper-doped MIL-101(Cr) (Cu@MIL-101(Cr)) were prepared through hydrothermal method and were used to remove volatile organic compounds (VOCs) in this study. Morphological characterization demonstrated that MIL-101(Cr) and Cu-3@MIL-101(Cr) were octahedral crystal, with specific surface area of 3367 and 2518 m²/g, respectively. The results of XRD, TG, and FTIR showed that the copper doping procedure would not alter the skeleton structure, but it would affect the crystallinity and thermal stability of MIL-101(Cr). Besides, MIL-101(Cr) and Cu-3@MIL-101(Cr) displayed good removal efficiencies on benzene sorption, and the maximum sorption capacity was 103.4 and 114.4 mg/g, respectively. In competitive adsorptions, the order of adsorption priority on Cu-3@MIL-101(Cr) was as follows: ethylbenzene > toluene > benzene. Hence, it could be concluded that MIL-101(Cr) and copper-doped MIL-101(Cr) demonstrated good performance in VOCs adsorption and showed a promising potential for large-scale applications in the removal of VOCs. Graphical abstract ᅟ.

Cd-free Cu-doped ZnInS/ZnS Core/Shell Nanocrystals: Controlled Synthesis And Photophysical Properties

Here, we report efficient composition-tunable Cu-doped ZnInS/ZnS (core and core/shell) colloidal nanocrystals (CNCs) synthesized by using a colloidal non-injection method. The initial precursors for the synthesis were used in oleate form rather than in powder form, resulting in a nearly defect-free photoluminescence (PL) emission. The change in Zn/In ratio tunes the percentage incorporation of Cu in CNCs. These highly monodisperse Cu-doped ZnInS CNCs having variable Zn/In ratios possess peak emission wavelength tunable from 550 to 650 nm in the visible spectrum. The quantum yield (QY) of these synthesized Cd-free CNCs increases from 6.0 to 65.0% after coating with a ZnS shell. The CNCs possessing emission from a mixed contribution of deep trap and dopant states to only dominant dopant-related Stokes-shifted emission are realized by a careful control of stoichiometric ratio of different reactant precursors during synthesis. The origin of this shift in emission was understood by using steady state and time-resolved fluorescence (TRF) spectroscopy studies. As a proof-of-concept demonstration, these blue excitable Cu-doped ZnInS/ZnS CNCs have been integrated with commercial blue LEDs to generate white-light emission (WLE). The suitable combination of these highly efficient doped CNCs results led to a Commission Internationale de l'Enclairage (CIE) color coordinates of (0.33, 0.31) at a color coordinate temperature (CCT) of 3694 K, with a luminous efficacy of optical radiation (LER) of 170 lm/Wopt and a color rendering index (CRI) of 88.

Assembling Ultrasmall Copper-Doped Ruthenium Oxide Nanocrystals into Hollow Porous Polyhedra: Highly Robust Electrocatalysts for Oxygen Evolution in Acidic Media

Here, a facile and novel strategy for the preparation of Cu-doped RuO2 hollow porous polyhedra composed of ultrasmall nanocrystals through one-step annealing of a Ru-exchanged Cu-BTC derivative is reported. Owing to the optimized surface configuration and altered electronic structure, the prepared catalyst displays a remarkable oxygen evolution reaction (OER) performance with low overpotential of 188 mV at 10 mA cm-2 in acidic electrolyte, an ultralow Tafel slope of 43.96 mV dec-1 , and excellent stability in durability testing for 10 000 cycles, and continuous testing of 8 h at a current density of 10 mA cm-2 . Density functional theory calculations reveal that the highly unsaturated Ru sites on the high-index facets can be oxidized gradually and reduce the energy barrier of rate-determining steps. On the other hand, the Cu dopants can alter the electronic structures so as to further improve the intrinsic OER activity.

Preliminary investigation of the effect of doping of copper oxide in CaO-SiO2-P2O5-MgO bioactive composition for bone repair applications

A diopside based bioactive system with a nominal composition of xCuO-(45.55-x)CaO-29.44 SiO₂-10.28P₂O₅-14.73 MgO (x=0,1,3 and 5mol%) has been prepared by sol gel technique in the laboratory. X-ray Diffraction, Fourier Transform Infra-Red and Raman Spectroscopy, Field Emission Scanning Electron Microscopy along with Energy Dispersive X-ray Analysis and pH studies have been undertaken on the prepared samples before and after dipping the samples in simulated body fluid. It has been observed that hydroxyapatite layer starts to form with in 24h during immersion in simulated body fluid. Degradation studies have also been employed to check the degradation behavior in Tris-HCl. Dynamic light scattering studies show that particles are mostly agglomerated and have an average size of 356nm. Zeta potential studies have been undertaken to check the surface charge and it has been estimated that samples carry negative charge when dipped in simulated body fluid. Negative surface charge may contribute to attachment and proliferation of osteoblasts. Samples have also shown the antimicrobial properties against the Vibro cholerae and Escherichia coli pathogens. To check the non-toxic nature of the samples, cell cytotoxic and cell culture studies have been undertaken using the MG-63 cell lines. Samples have shown good response with good percentage viability of the cells in the culture media and hence, provides friendly environment to the growth of cells. The particle size, bioactivity, negative values of zeta potential, antimicrobial properties and good cell viability indicate the potential of the synthesized compositions as possible candidates for bone repair applications.