CuO Microspheres Research Articles

Porous CuO Microspheres as Long-Lifespan Cathode Materials for Aqueous Zinc-Ion Batteries.

Cathode materials with conversion mechanisms for aqueous zinc-ion batteries (AZIBs) have shown a great potential as next-generation energy storage materials due to their high discharge capacity and high energy density. However, improving their cycling stability has been the biggest challenge plaguing researchers. In this study, CuO microspheres were prepared using a simple hydrothermal reaction, and the morphology and crystallinity of the samples were modulated by controlling the hydrothermal reaction time. The as-synthesized materials were used as cathode materials for AZIBs. The electrochemical experiments showed that the CuO-4h sample, undergoing a hydrothermal reaction for 4 h, had the longest lifecycle and the best rate of capability. A discharge capacity of 131.7 mAh g-1 was still available after 700 cycles at a current density of 500 mA g-1. At a high current density of 1.5 A g-1, the maintained capacity of the cell is 85.4 mA h g-1. The structural evolutions and valence changes in the CuO-4h cathode material were carefully explored by using ex situ XRD and ex situ XPS. CuO was reduced to Cu2O and Cu after the initial discharge, and Cu was oxidized to Cu2O instead of CuO during subsequent charging processes. We believe that these findings could introduce a novel approach to exploring high-performance cathode materials for AZIBs.

Structural Colored Fabric Based on Monodisperse Cu2O Microspheres.

Structural-colored fabrics have been attracting much attention due to their eco-friendliness, dyelessness, and anti-fading properties. Monodisperse microspheres of metal, metal oxide, and semiconductors are promising materials for creating photonic crystals and structural colors owing to their high refractive indices. Herein, Cu2O microspheres were prepared by a two-step reduction method at room temperature; the size of Cu2O microspheres was controlled by changing the molar ratio of citrate to Cu2+; and the size of Cu2O microspheres was tuned from 275 nm to 190 nm. The Cu2O microsphere dispersions were prepared with the monodispersity of Cu2O microspheres. Furthermore, the effect of the concentration of Cu2O microsphere and poly(butyl acrylate) on the structural color was also evaluated. Finally, the stability of the structural color against friction and bending was also tested. The results demonstrated that the different structural colors of fabrics were achieved by adjusting the size of the Cu2O microsphere, and the color fastness of the structural color was improved by using poly(butyl acrylate) as the adhesive.

Mesoporous Cu2O microspheres for highly efficient C2 chemicals production from CO2 electroreduction

Production of C2 chemicals (such as C2H4, C2H5OH, etc.) from CO2 electroreduction reaction (CO2ER) has been regarded as a promising route to solve the environmental problems and energy crisis. In this work, mesoporous Cu2O microspheres of ca. 700 nm diameter size with low crystallinity were fabricated to enable efficient conversion of CO2 to C2 chemicals by electrocatalytic reduction. It is revealed that compared with bulk Cu2O, the obtained mesoporous Cu2O microspheres have larger surface area, more grain boundaries and defects (unsaturated coordination sites), which facilitate the adsorption and stabilization of the important intermediates, such as *CO, on the route to C2 chemicals formation. As a result, the Faraday efficiency (FE) of C2 products reaches as high as 82.6 % and 78.5 % in an H-cell and a flow cell, respectively. In situ Raman and FT-IR spectra reveal that during CO2ER test there exists abundant *CO on the mesoporous Cu2O surface, thus increasing the opportunity of CC coupling. And the high coverage of *CO on catalyst surface during CO2ER protects and stabilizes the oxidation state of Cu species. This work demonstrates an effective strategy to introduce mesoporous structures and decreased crystallinity for improving the performance of CO2ER to C2 products.

Enhancing local K+ adsorption by high-density cube corners for efficient electroreduction of CO2 to C2+ products.

Reducing carbon dioxide (CO2) to high value-added chemicals using renewable electricity is a promising approach to reducing CO2 levels in the air and mitigating the greenhouse effect, which depends on high-efficiency electrocatalysts. Copper-based catalysts can be used for electroreduction of CO2 to produce C2+ products with high added value, but suffer from poor stability and low selectivity. Herein, we propose a strategy to enhance the field effect by varying the cubic corner density on the surface of Cu2O microspheres for improving the electrocatalytic performance of CO2 reduction to C2+ products. Finite element method (FEM) simulation results show that the high density of cubic corners helps to enhance the local electric field, which increases the K+ concentration on the catalyst surface. The results of CO2 electroreduction tests show that the FEC2+ of the Cu2O catalyst with high-density cubic corners is 71% at a partial current density of 497 mA cm-2. Density functional theory (DFT) calculations reveal that Cu2O (111) and Cu2O (110) can effectively reduce the energy barrier of C-C coupling and improve the FEC2+ at high K+ concentrations relative to Cu2O (100). This study provides a new perspective for the design and development of efficient CO2RR catalysts.

Template Based Synthesis of Porous Graphdiyne Nanosheet for Reversible and Fast NO2 Detection by UV Irradiation.

Two-dimensional graphdiyne (GDY) formed by sp and sp2 hybridized carbon has been found to be an efficient toxic gas sensing material by density functional theory (DFT). However, little experimental research concerning its gas sensing capability has been reported owing to the complex preparation process and harsh experimental conditions. Herein, porous GDY nanosheets are successfully synthesized through a facile solvothermal synthesis technique by using CuO microspheres (MSs) as both template and source of catalyst. The porous GDY nanosheets exhibit a broadband optical absorption, rendering it suitable for the light-driven optoelectronic gas sensing applications. The GDY-based gas sensor was demonstrated to have excellent reversible to NO2 behaviors at 25 °C for the first time. More importantly, higher response value and faster response-recovery time once exposed to NO2 gas molecules are achieved by the illumination of UV light. In this way, our work paves the way for the exploration of GDY-based gas detection experimentally.

Cu2O@TiO2 core-shell microspheres for naphthalene oxidation

New Cu2O@TiO2 core-shell microspheres were successfully prepared for the first time in this paper. The XRD, N2 adsorption-desorption, SEM, TEM, EDX and XPS characterizations were utilized to investigate the physical and chemical properties. The liquid phase oxidation of naphthalene was also carried out to test their catalytic performance. The characterization results indicating that the Cu2O microspheres were firstly formed by hydrothermal treatment and the rutile TiO2 coating on the surface would be formed by the hydrolysis of tetrabutyl titanate. The Cu2O@TiO2-5.0 catalyst with the molar ratio of copper to titanium species as high as 5.0 has the largest surface area and maximum pore volume resulting from the integrated microspheres with rougher surface thickness of about 6.3 nm, and it showed higher catalytic performance in the liquid phase oxidation of naphthalene. Naphthalene conversion of 43.2%, 1, 4-naphthoquinone selectivity of 26.7% and phthalic anhydride selectivity of 53.4% can be obtained, and it only slightly decreased even after repeated use for 5 times. The method would provide a valuable theoretic reference for the hindrance of Cu2O rapid deactivation and the industrial application of the naphthalene oxidation to produce high valuable chemicals.

Influence of Copper-Based Fillers on Structural and Mechanical Properties of Polylactic Acid Composites

The importance of promising composites in modern materials science is constantly increasing. The use of various fillers or additives is associated with their influence not only on the defining properties of the composite, but also on physical and mechanical characteristics of the material. In this case, the distribution of the additive and its wetting with a polymer play an important role. The problem highlighted in this article is the influence of different copper-containing fillers (copper (II) sulphate powder, micro-sized copper (II) oxide powder, and nano-structured copper (II) oxide-based hollow microspheres) on the technological and physical–mechanical properties of the composites based on polylactic acid (PLA). The hollow microspheres of copper (II) oxide have been obtained by ultrasonic spray atomization via pyrolysis of copper (II) nitrate. The structure of the copper-based additives has been studied using X-ray diffraction, scanning electron microscopy, and static light scattering. For the PLA-composites, scanning electron microscopy, differential scanning calorimetry, stress-strain properties testing, and density analysis have been performed. The plasticizing effect of polycaprolactone and polyethylene glycol has been studied for the highly filled PLA/CuSO4 composite. The samples of PLA with over 2 wt.% of CuO microspheres have a full volume-filling and percolation structure of the additive’s particles. Due to the regular spherical shape of the particles and a lower specific volume, CuO hollow microspheres are uniformly distributed in the PLA matrix acting as a structuring and reinforcing modifier. Differential scanning analysis showed heterogeneous crystallization on CuO particles with an increase in the degree of crystallinity and the melting point of the polymer. It has been shown that the pre-masterbatching technology and adding plasticizers to obtain PLA composites contribute minimizing defects and enhance mechanical properties.

Reactive Characteristics of Novel Core‐Shell Al−CuO Microspheres Prepared by Alcohol‐Thermal Treatment of Cu(OH)2

AbstractIn this study, core‐shell structured Al@CuO energetic microspheres are prepared through the alcohol‐thermal method. CuO is grown in situ around superfine Al powder, and Cu(OH)2 powder is used directly as the precursor for CuO growth. The effects of reaction temperature and reaction time on the chemical transformation as well as coating quality are investigated by using scanning electron microscopy, transmission electron microscopy and X‐ray diffraction. More importantly, the transformation of Cu(OH)2 into CuO during alcohol‐thermal process is tentatively discussed. And the growth mechanisms of CuO are speculated, which mainly consist of the continuous dissolution of Cu(OH)2, the transformation of dissolved Cu(OH)2 to CuO which happens at a lower temperature than that of dry Cu(OH)2 powder, and the heterogeneous nucleation and growth of CuO. The prepared Al@CuO energetic microspheres are compared with physically mixed Al/CuO counterparts by using thermal analysis, electric ignition and constant‐volume combustion tests. Benefiting from the improved interfacial contact quality, Al@CuO energetic microspheres show overall enhanced reaction characteristics in terms of reaction onset temperature, heat release, apparent activation energy, ignition delay, burning time and pressurization rate.

Design of tandem CuO/CNTs composites for enhanced tetracycline degradation and antibacterial activity

The increasingly complex situation of the water environment has put forward higher requirements for the development of functional materials for comprehensive water environmental management. Here, a facile microwave self-assembly strategy was proposed to construct a tandem copper oxide/carbon nanotube (CuO/CNTs) composite. The characterization of the structure shows that the CNTs have been associated with porous CuO nanospheres, forming an interpenetrating architecture. We identified generated reactive oxygen species including sulfate radicals (SO4−), hydroxyl radicals (OH), singlet oxygen (1O2), and superoxide radical (O2−), which can rapidly improve the degradation of tetracycline (TC). Compared with individual CuO microspheres or CNTs, the reaction rate of TC on the CuO/CNTs is improved 1.9 and 6.5 times, respectively. In addition, we confirmed that the reactive oxygen species produced had an effectively inhibitory effect on common types of bacteria. Density functional theoretical (DFT) calculations show that the adsorption energy of PMS on the opposite side of graphene is favorable (−0.517 eV). The CuO/CNTs catalysts with excellent intrinsic properties suggest its wide potential applications in wastewater treatment.

Preparation and application of (Cu2O‐Ag)@TA composite nanomaterials with enhanced stability and photocatalytic antibacterial activity

AbstractFood spoilage caused by bacterial growth is a serious threat to human health, so food preservation technology with long‐acting antibacterial effect has been widely studied. In this work, (Cu2O‐Ag)@TA heterojunction composite antibacterial material with a core‐shell structure was synthesized to improve the stability of Cu2O. Morphological characterization shows that silver nanoparticles are uniformly distributed on the surface of Cu2O microspheres, (Cu2O‐Ag)@TA has a core‐shell structure, the particle size is about 300 nm, and the thickness of the tannic acid shell is about 6 nm. In addition, (Cu2O‐Ag)@TA exhibits excellent dispersibility and stability, it can stably release Cu2+ within 14 days and has enhanced reactive oxygen species release performance, thus achieving excellent antibacterial properties, with a minimum inhibitory concentrations of 96 μg ml−1 against Escherichia coli and Staphylococcus aureus. In addition, adding (Cu2O‐Ag)@TA into the LbL‐PVA/CS/FA composite film can improve the mechanical properties and antibacterial ability of the composite film, providing a feasible solution for new biodegradable antibacterial packaging materials.

Excellent photocatalytic performance and dual-band degradation of organic pollutants through Z-scheme photocatalysts

Organic pollutants, particularly nitrogen-rich explosives and carbon-rich dyes are generally degraded by different photocatalysts under either visible or ultraviolet light, leading to substantial waste and cost. Three photocatalysts with Z-scheme structures, Ag@AgBr/Cu2O-1, Ag@AgBr/Cu2O-2, and Ag@AgBr/Cu2O-3, are designed and synthesized employing a simple solvothermal and photoreduction technique to develop advanced photocatalyst materials that can degrade nitro substances under ultraviolet (UV) irradiation and organic dyes under visible-light irradiation. The structural characterization of Ag@AgBr/Cu2O-2 as determined through various spectroscopic techniques (e.g. XPS, XRD and TEM) reveal that the Z-scheme photocatalysts are composed of Ag, Cu2O and AgBr nanospheres with particle size less than 100 ​nm, while nano-Ag and nano-AgBr coupled to the surface of the Cu2O microspheres. Further investigations demonstrate that these photocatalysts exhibit a good UV–visible absorption range (200–800 ​nm) and outstanding photocatalytic degradation activity for two typical organic pollutants. Among them, Ag@AgBr/Cu2O-2 achieve a 100% degradation of trinitrotoluene (a common explosive) in 30 ​min under UV radiation, and a 99.2% degradation of rhodamine B (a typical dye) in 60 ​min under visible-light irradiation in the absence of UV light, demonstrating remarkable dual-band adaptability. Moreover, Ag@AgBr/Cu2O-2 displays superior stability, with a degradation rate of up to 85% after four cycles. The putative photocatalytic reaction mechanism is proposed based on the radical trapping experiment.

Wireless Volatile Organic Compound Detection for Restricted Internet of Things Environments Based on Cataluminescence Sensors

Cataluminescence-based sensors do not require external light sources and complex circuitry, which enables them to avoid light scattering with high sensitivity, selectivity, and widely linear range. In this study, a wireless sensor system based on hierarchical CuO microspheres assembled from nano-sheets was constructed for Volatile Organic Compound (VOC) online detection. Through sensor characteristics and data process analysis, the results showed that the luminous sensor system has good luminous characteristics, including the intensity of visible light, high signal/noise (S/N) values, and very short response and recovery times. Different VOC concentration values can be detected on multiple wavelength channels and different Cataluminescence signal spectra separations can process multiple sets of Cataluminescence data combinations concurrently. This study also briefly studied the mechanism action of the Cataluminescence sensor, which can specifically be used for VOC detecting.

0D-2D Cu2O microspheres@rGO composite for enhanced sodium storage

A cuprous oxide microspheres@reduced graphene oxide (Cu2O@rGO) composite is successfully prepared and used as an anode active material for sodium-ion batteries. In the hybrid structure, large-sized 0D Cu2O microspheres (∼500 nm) are distributed on highly conductive 2D rGO layers. The Cu2O@rGO electrode delivers a high reversible capacity of 273.2 mAh g−1 at a current density of 50 mA g−1 after 100 cycles, significantly higher than regular-sized (less than100 nm) Cu2O/rGO composite (185.9 mAh g−1) and bare Cu2O particles (95.8 mAh g−1). Even at 1 A g−1, Cu2O@rGO still demonstrates a capacity of 189 mAh g−1 after 1000 cycles. The enhanced electrochemical performance of Cu2O@rGO might be ascribed to the continuous and stable 3D network structure, which is transformed from the unique large-sized 0D-2D architecture after cycling. The as-fabricated hybrid structure shows great potentials in energy storage applications.

Sensitive photoelectrochemical detection of colitoxin DNA based on NCDs@CuO/ZnO heterostructured nanocomposites with efficient separation capacity of photo-induced carriers.

Ametal-organic framework (MOF) of Cu-TPA (terephthalic acid) microsphere was prepared, followed by calcinating the MOF precursor of Cu-TPA/ZIF-8 mixture to obtain the CuO/ZnO. N-doped carbon dots (NCDs) were employed to combine the CuO/ZnO composite to form a tripartite heterostructured architecture of NCDs@CuO/ZnO, which led to a fierce enlargement of the photocurrent response. This was ascribed to the thinner-shell structure of the CuO microsphere and the fact thathollow ZnO particles could sharply promote the incidence intensity of visible light. The more porous defectiveness exposed on CuO/ZnO surface was in favor of rapidly infiltrating electrolyte ions. The p-n type CuO/ZnO composite with more contact interface could abridge the transfer distance of photo-induced electron (e-1)/hole (h+) pairs and repress their recombination availably. NCDs not only could boost electron transfer rate on the electrode interface but also successfully sensitized the CuO/ZnO composite, which resulted in high conversion efficiency of photon-to-electron. The probe DNA (S1) was firmly assembled on the modified ITO electrode surface (S1/NCDs@CuO/ZnO) through an amidation reaction. Under optimal conditions, the prepared DNA biosensor displayed a wide linear range of 1.0 × 10-6 ~ 7.5 × 10-1nM and a low limit of detection (LOD) of 1.81 × 10-7nM for colitoxin DNA (S2) measure, which exhibited a better photoelectrochemistry (PEC) analysis performance than that obtained by differential pulse voltammetry techniques. The relative standard deviation (RSD) of the sensing platform for target DNA detection of 5.0 × 10-2nM was 6.3%. This proposed DNA biosensor also showed good selectivity, stability, and reproducibility, demonstrating that the well-designed and synthesized photoactive materials of NCDs@CuO/ZnO are promising candidates forPEC analysis.

Ultrasensitive SERS substrates based on Au nanoparticles photo-decorated on Cu2O microspheres for the detection of rhodamine B and methylene blue

Integrating noble-metal and semiconductor nanomaterials for Raman signal enhancement is of great significance in the field of surface enhanced Raman spectroscopy (SERS). In this work, a SERS-active substrate composed of Au nanoparticles (NPs) on Cu2O microspheres is produced by the polyol and photochemical methods for the effective detection of organic dye molecules, rhodamine B (RhB) and methylene blue (MB). The formation of Au/Cu2O nanostructure is confirmed by X-ray diffraction, field emission scanning electron microscopy , elemental mapping and UV-Vis spectroscopy. The proposed heterogeneous nanomaterials have high SERS activity by the synergistic interaction among Au NPs, Cu2O microspheres and organic dye molecules through electromagnetic and chemical mechanisms. The photochemical parameter for the growth of Au NPs and Cu2O microspheres is optimized by elevating the SERS signal intensity to high extent. The measured analytical enhancement factors (AEFs) are as high as 2.55 × 1012 for RhB and 1.2 × 1011 for MB. The corresponding limits of detection (LOD) are 2.36 × 10-13 M for RhB and 3.40 × 10-12 M for MB. The reproducibility and the uniformity with the relative standard deviation (RSD) < 10% confirm the superiority of the proposed SERS substrate. The real-sample analysis of RhB in the chili solution and MB in the pond water gives the satisfactory recovery values > 87.8%. This reliable and facile production approach is practically applicable to produce SERS-active substrates in various real applications.

Synergistic effect of PdO and parallel nanowires assembled CuO microspheres enables high performance room-temperature H2S sensor

High-performance semiconductor gas sensors comprising of metal oxides have offered appealing promise to environment monitor devices but remain challenging due to their high working temperature and sluggish response/recovery speed. Here we report a simple impregnation method that utilizing the high catalytic activity of palladium oxide activates copper oxide parallel nanowires assembled hierarchical microspheres (PdO-CuO NWMs). And then gas-sensing devices with different decorating concentrations were fabricated to investigate their sensing performance on hydrogen sulfide (H2S). It was demonstrated that the CuO microspheres with 2 wt% PdO decorating concentration is the optimum, with high response of 6.8 and extremely short response/recovery time of 1.8/4.1 s towards 50 ppm H2S at 30 °C, effective enhancing the response (4.9–50 ppm H2S) and working temperature (150 °C) of pristine CuO NWMs sensor. The boosting sensing performance of our PdO-CuO NWMs gas sensor was attributed to the synergistic effect of high catalytic noble nanoparticles and hierarchical structures. The coupling strategy offers new insights to explore room temperature and real-time monitoring gas sensors.

Preparation of nanoparticles-assembled Cu2O microspheres by ultrasound- assisted polyol process and their adsorption performance

Preparation of nanoparticles-assembled Cu2O microspheres by ultrasound- assisted polyol process and their adsorption performance

Peapod-like architectures with CuO microspheres encapsulated within MXene as a conversion electrode for lithium-ion batteries.

Conversion electrode materials allow lithium-ion batteries to achieve high reversible capacities but have the problem of sluggish kinetics derived from their insulating decomposition products, thus hindering their future application. Nanostructures that shorten diffusion distances do not solve the problem as the conversion reaction is always associated with the collapse of the original structure. Here, we demonstrate that MXene would be a good conductive additive for conversion electrode materials and utilize an electrode of CuO incorporated into a MXene scaffold as a model case which demonstrates highly improved cyclability with a capacity of 670 mA h g-1 at 5C after 1000 cycles.

Synthesis of CuO/rGO nanocomposites for carcinogenic Congo red photodegradation

Removal of carcinogenic Congo red from polluted water is challenging because of its chemical stability and inertness. Here, CuO microsphere assembled rGO nanosheets were successfully fabricated by a simple hydrothermal method for photocatalytic degradation of Congo red. The morphology and microstructure of the CuO/rGO nanocomposites were studied by scanning electron microscopy and X-ray diffraction. The results showed that the produced CuO has a spherical flower like structure that crystallised in the monoclinic crystal phase with a diameter of about 5 μm, combined with thin rGO nanoplates. Fourier transform infrared spectroscopy and Raman spectroscopy confirmed the existence of chemical bonds and vibrational modes of both CuO and rGO. The effect of H2O2 content on the photocatalytic characteristics of as-prepared samples was investigated. The results showed that H2O2 played a key factor in the photocatalytic efficiency. The content of 1 ml H2O2 (30%) exhibited the highest photocatalytic efficiency toward Congo red dye degradation in CuO/rGO (50 mg) under UV light radiation, where it completely removed over 95% Congo red in 100 ml of solution (20 mg L−1) after 120 min of illumination.

Facile Synthesis of 3D Sea Urchin-like CuO Microspheres Structures and its Higher Photocatalytic Properties

The three-dimensional (3D) sea urchin-like CuO microspheres structures were successfully synthesized by a simple hydrothermal method. With the hydrothermal temperature increases, the morphology of CuO micro-/nanostructures has changed: When the hydrothermal temperature reaches above 40 °C, the irregular CuO particles transform into a 3D sea urchin-like CuO microspheres. X-ray diffraction spectrum and Raman scatting spectra confirm that the obtained 3D sea urchin-like CuO microspheres at hydrothermal temperature of 60 °C are composed of a high purity and single-phase monoclinic CuO. It is found that the 3D sea urchin-like CuO microspheres structures exhibit the better photocatalytic property for degradation of methylene blue (MB) solution under the visible light irradiation compared to the irregular CuO particles, which duo to the relatively larger specific surface area of the sea urchin-like CuO microspheres structures, exposing more active sites and increasing the contact area between the catalyst and dye molecule. This remarkable photocatalytic performance of the 3D sea urchin-like CuO microspheres structures might has a promising application in waste water treatment.