Cu2O Nanospheres Research Articles

Tightly Interfaced Cu2O with In2O3 to Promote Hydrogen Evolution in Presence of Biomass‐Derived Alcohols

By a mild and straightforward synthetic protocol in aqueous solution and without surfactants, hierarchical Cu2O nanospheres were grown on preformed In2O3 nanostructures, varying the ratio In:Cu (2.5, 0.5). Accordingly, two different binary compounds In2O3‐Cu2O were prepared and afterwards they were integrated with TiO2 NPs. The ternary composites having a loading of 2.0, 5.0 and 10.0 wt.% respectively of binary In2O3‐Cu2O, were tested as photocatalysts in the solar‐driven production of hydrogen from water, using as sacrificial agents alcohols derived from the biomass. Satisfyingly, the rate of H2 evolution (20.5 mmol/g h) resulted two orders of magnitude higher respect to bare TiO2 (0.2 mmol/g h). Electrochemical impedance spectroscopy and photoluminescence measurements revealed the formation of a tight heterojunction between In2O3 and Cu2O, which is responsible for the improved charge carrier density and transfer and for the diminished electron‐hole recombination.

Visible-light responsive CuO-ZnO nanostructure synthesized using Muntingia calabura extract for efficient H2O2 evolution and organic pollutant degradation

In this study, ZnO-CuO heterostructures were synthesized via a green approach using Muntingia calabura leaf extract with insights into the precursor ratio for enhanced photocatalytic performance. The synthesized materials were characterized by modern analytic methods, including X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry, which elucidated the presence of CuO nanospheres and ZnO semi-cuboids. Thanks to a lower bandgap of 2.24 eV compared to pristine ZnO (2.82 eV), better visible light absorption, and longer charge lifetime, the optimal ZC16 sample, corresponding to a Cu:Zn ratio of 1:16, achieved a hydrogen peroxide production of 350.23 μM under visible light that was further increased to 478.98 μM with oxygen aeration. In addition, ZC16 also demonstrated excellent photodegradation performance towards malachite green (95.82 %) and tetracycline (97.78 %). Disclosure into the photocatalytic mechanism of both processes revealed the significant roles of active radicals, which have proven the environmentally friendly and cost-efficient synthesis pathway of ZnO-CuO heterostructures for environmental remediation and clean energy applications.

Functional structural color based on Cu2O nanospheres with brilliant colors and excellent antibacterial properties

Functional structural color based on Cu2O nanospheres with brilliant colors and excellent antibacterial properties

A novel photoelectrochemical biosensing platform utilizing dual Type-II Bi2O3/CdLa2S4/Bi2S3 ternary heterojunctions as signal transduction materials and Cu2O nanosphere as a sensitizer for CA15-3 detection

Sensitive detection of CA15-3 is important for postoperative monitoring and early diagnosis of breast cancer. In this work, a photoelectrochemical (PEC) biosensing platform was constructed of CA15-3 by using Bi2O3/CdLa2S4/Bi2S3 ternary type-II heterojunction as the photoactive transduction material for sensitive detection, and the raspberry-shaped Cu2O nanospheres were exploited as the signal sensitizing tags. On one hand, the use of Bi2S3 as a sensitizer can effectively enhance the visible light excitation of the substrate material. On the other hand, Bi2S3 and Bi2O3/CdLa2S4 have the ability to create dual type-II heterojunctions with matched energy levels, which significantly enhances the separation and migration efficiency of the photogenerated carriers and effectively suppresses the recombination of the e-/h+ pairs. Raspberry-like semiconducting Cu2O nanospheres can mediate the PEC process of the heterojunctions. An immunosensor was developed combining the signal transduction capacity of ternary heterojunction and the signal sensitizing effect of Cu2O nanospheres. The proposed PEC immunosensor showed good selectivity and stability for detecting CA15-3 (0.001 ∼ 100 U/mL) with a detection limit of 0.0003 U/mL (S/N = 3). The constructed PEC immunosensor had potential applications in the clinical detection of CA15-3, and was expected to play a great role in the early diagnosis of breast cancer in the future. Moreover, in the design engineering of photoactive materials, the improvement of visible excitation and the enhancement of carrier separation efficiency have been realized simultaneously using a single material, which provides new ideas for the design of photoactive materials.

Electrodeposition of CoFeS nanoflakes on Cu2O nanospheres as an ultrasensitive sensing platform for measurement of the hydrazine and hydrogen peroxide in seawater sample

Nanoarchitectured design of the metal sulfides with highly available surface and abundant electroactive centers and using them as electrocatalyst for fabricate the electrochemical sensors for the detection of hydrazine (N2H4) and hydrogen peroxide (H2O2) is challenging and desirable. Herein, Cu2O nanospheres powder is firstly prepared using chemical reduction of copper chloride and then drop-casted on the glassy carbon electrode (GCE) surface. In the next step, CoFeS nanoflakes are electrodeposited on Cu2O nanospheres by cyclic voltammetry method to form CoFeS/Cu2O nanocomposite as a detection platform for measuring N2H4 and H2O2. Accordingly, Cu2O nanospheres are not only used as substrate, but also guided the CoFeS nanoflakes to adhere to the electrode surface without need to any binder or conductive additive, which enhances the electrical conductivity of the sensing active materials. As the hydrazine sensor, the CoFeS/Cu2O/GCE displayed wide linear ranges (0.0001–0.021 mM and 0.021–1.771 mM), low detection limit (0.12 μM), very high sensitivities (103.33 and 21.23 mA mM−1 cm−2), and excellent selectivity. The as-made nanocomposite also exhibited low detection limit of 1.26 μM for H2O2 sensing with very high sensitivities (12.31 and 3.96 mA mM−1 cm−2) for linear ranges of 0.001–0.03 mM and 0.03–2.03 mM, respectively, and negligible response against interfering substances. The superior analytical performance of the CoFeS/Cu2O for N2H4 electro-oxidation and H2O2 electro-reduction can be attributed to structure stability, high electroactive surface area, and good availability to analyte species and electrolyte diffusion. Moreover, to examine the potency of the prepared nanocomposite in real applications, the seawater sample was analyzed and results display that the CoFeS/Cu2O/GCE can be utilized as a reliable and applicable platform for measuring N2H4 and H2O2.

Tailoring the interior structure of Cu2O Shell-in-Shell nanospheres for high-performance electrocatalytic nitrate-to-ammonia conversion

Electrocatalytic nitrate reduction is one of the most promising technology for removing harmful nitrate from water while simultaneously producing value-added ammonia. Regulating the internal structure of the benchmark electrocatalyst copper can further improve nitrate-to-ammonia conversion performance. Herein, we synthesized a series of hollow multi-shell structured Cu2O nanospheres (NSs) via a multistep Ostwald ripening method, and evaluated their nitrate-to-ammonia conversion performance. Results show that 2-shell Cu2O NSs demonstrated the highest nitrate conversion (98.1 %), ammonia selectivity (80.2 %), ammonia Faradic efficiency (70.3 %) and reaction rate constant (0.03 min−1) for nitrate-to-ammonia conversion. Important influencing factors are also examined including applied potentials and nitrate concentrations. Mechanistic study unravels that the outstanding electrocatalytic performance of 2-shell Cu2O NSs originates from the strongest nitrite adsorption so as to enhance nitrate-to-ammonia conversion. Materials characterizations verify that Cu2O NSs were reduced to metallic copper that severed as the real active site during electrocatalytic nitrate reduction. This work unveils the interior structure-dependent electrocatalytic performance of Cu2O NSs for nitrate-to-ammonia conversion, which offers a practical strategy to design structurally novel heterogeneous catalysts for various applications.

In-situ deposition of silver nanoparticles on cuprous oxide hollow spheres for sensitive and recyclable SERS sensing in solution based on electromagnetic and chemical enhancement

In order to achieve widespread application of surface-enhanced Raman spectroscopy (SERS) technique for practical sensing illegal additives in food, it is crucial to construct a reliable SERS substrate that offers both high sensitivity and reusability. This work utilized a simple and rapid in-situ deposition method to deposit Ag nanoparticles onto hollow Cu2O nanospheres, resulting in the formation of Cu2O/Ag nanocomposites with photocatalytic and SERS properties. These nanocomposites were employed as a hopeful SERS analysis for effective sensing of colorant additives in fruit juice, including methylene blue (MB) and rhodamine 6G (R6G). Impressively, the nanocomposites exhibited an exceptional detection limit of 10−9 M for the color agents and demonstrated a strong linear relationship between SERS intensities and the logarithmic concentration (R2 ≥ 0.95). The hollow structure of Cu2O provided low density and long-term dispersion stability in solution, which are beneficial for real-time monitoring the additives in liquid food. The excellent SERS performance can be attributed to the electromagnetic effect of Ag metals and the chemical enhancement of Cu2O semiconductors, as confirmed by the N 1 s XPS spectra from MB. Furthermore, the Cu2O/Ag nanocomposites efficiently degraded dye molecules under UV light irradiation within a short period of 45 min. So, the nanocomposites exhibited practical recyclability, as demonstrated by their consistent performance over five cycles of SERS sensing. These findings highlight their significant potent for SERS sensing trace pollutants and ecological restoration by photocatalytic reaction in the future.

Effect of Cu2O nanosphere size on femtosecond laser reductive sintering/melting for Cu printing

In this study, the size effect of Cu2O nanospheres on femtosecond laser reductive sintering/melting properties for Cu printing is investigated. First, two types of monodispersed Cu2O nanospheres (average sizes of 110 and 250 nm) are prepared using the polyol method. The particle size is significantly affected by the amount of polyvinylpyrrolidone because of the capping of initially-precipitated nanospheres and their aggregations. Both the prepared inks containing nanospheres and reducing agents exhibit the same reaction temperature in thermogravimetry and differential thermal analyses. These results indicate that the size of the nanospheres does not affect the reaction temperature. The small Cu2O nanospheres are well-sintered, whereas the large nanospheres are easily melted by irradiation with femtosecond laser pulses. As both inks possess the same reaction temperature, their printing properties depend on their thermal conductivity. The low thermal conductivity of the large nanosphere ink owing to their small reduced surfaces against volume induces local heating and subsequent melting, and the high thermal conductivity of the small nanosphere ink owing to their large reduced surfaces against volume increases sintering area. The sintered patterns fabricated using the small nanospheres exhibited an electrical conductivity of ∼1.1 × 106 S/m, which is 1/50 of pure Cu. These strong size effects of the nanospheres on direct writing demonstrate that mixed sizes of the nanospheres can improve the electrical conductivity of the patterns because of their high density and sufficient thickness.

Facile synthesis of porous Cu2O hollow nanospheres for accelerating electroreduction of CO2 towards C2 products

In this paper, porous Cu2O hollow nanospheres (Cu2O-HNSs) were facilely synthesized through a template-free one-pot wet-chemical method. Systematical investigations found that Cu2O-HNSs with many cavities on the shell were formed from porous Cu2O nanospheres through Ostwald ripening. The concentration of NH2OH∙HCl and pH value play critical roles. Compared to Cu powder, Cu2O-HNSs showed enhanced current density and Faraday efficiency of C2 products in electroreduction of CO2 (CER). Our work inspires the synthesis of hollow nanostructures to accelerate the formation of C2 products for CER.

Mechanism insight into the enhanced photocatalytic purification of antibiotic through encapsulated architectures coupling of crystalline Cu2O/amorphous TiFe layer double hydroxide

Amorphous materials are one of the important candidates for improving heterogeneous photocatalysts because of their unique electronic structures and abundant catalytic sites originating from disorder atomic arrangements. However, there is still much room for the development of new crystalline/amorphous heterogeneous composites for photocatalytic application. Hence efficient synthetic strategies for preparing new crystalline/amorphous heterojunctions are highly desired. Herein, we have realized the deep optimization of photocatalytic activity by fabricating crystalline/amorphous Cu2O/Ti-Fe layer double hydroxide (LDH) heterojunctions. Thanks to the typical Z-scheme mechanism originating from the crystalline/amorphous interfaces, the photocharge separation and catalytic active sites obviously enhance compared to single Cu2O and LDH counterparts. As expected, the photocatalytic removal of tetracycline (TC) of the as-prepared Cu2O/Ti-Fe LDH was over 5.2 and 2.2 times those of the pristine Cu2O nanospheres and Ti-Fe LDH nanosheets. This work illustrates the origin of crystalline Cu2O nanospheres encapsulated in amorphous Ti-Fe layer double hydroxide nanosheets for enhanced photocatalytic activity driven by visible light, and provide a general Cu2O-templated solution-phase synthetic method for the synthesis of novel double-metal layer double hydroxide amorphous nanostructures.

UV-activated CuO nanospheres modified with rGO nanosheets for ppb-level detection of NO2 gas at room temperature

Monitoring and reducing NO2 pollution at room temperature is indispensable for human survival. Thus, we propose a light-activated route (UV light, 100 mW/cm2) to realize a high-performance NO2 detection based on CuO/rGO gas sensor. The CuO/rGO sensor under UV light illumination exhibits a high response of 22.18–100 ppm NO2 at 23 ℃, which is approximately 1.36 times of the CuO/rGO sensor and 2.31 times of the CuO sensor under dark, respectively. Meanwhile, under UV light illumination, the CuO/rGO sensor has a fast response/recovery speed of 10.9/30.9 s to 20 ppm NO2 at 23 ℃, which is obviously better than that under dark. Moreover, the light-activated CuO/rGO sensor has excellent repeatability, selectivity, ultra-low detection limit (50 ppb) and long-term stability. The significantly appealing gas-sensing performance of CuO/rGO sensor is mainly ascribed to the mesoporous structure, high specific surface area and plentiful oxygen vacancy of CuO/rGO nanocomposites. More attractively, the photo-generated carriers and formed heterojunction also greatly improve the carrier migration in the context of the NO2/CuO/rGO interaction, enhancing the gas-sensing performance of gas sensor. Our work will provide insight in utilizing light illumination to realize ultrasensitive and room-temperature detection of ppb-level NO2 gas.

Facilitating electroreduction CO2-to-C2H4 over doped CuO nanospheres assisted by nitrogen species and oxygen vacancies

Electrocatalytic reduction is a promising strategy for CO2 utilization, while the conversion of CO2 to C2 products usually suffers from the low selectivity. Herein, we report several high-performance Cu-OCN catalysts for electroreduction CO2-to-C2H4, which are prepared through the in-situ calcination of nanocube Cu2O and urea. The highest C2H4 faradaic efficiency from Cu-OCN-10 reaches 55.97%, much higher than that from the pristine CuO counterpart (38.31%), with a partial current density of −12.83 mA cm−2. Catalyst characterizations and first-principles density functional theory calculations reveal that the superior performance of CuO-OCN is attributed to the introduced nitrogen (N) species and oxygen (O)-vacancies. With the assistance of N species and O-vacancies, the adsorption of CO2 on Cu-OCN-10 is thermodynamically favorable with the absorption energy of −0.69 eV. Meanwhile, the activation of CO2 is promoted and the generated *CO intermediate on Cu-OCN-10 is stable, whose release needs to overcome an energy of 2.26 eV, thereby enhancing the CC coupling to produce C2H4. In general, the synergistic effects of N species and O-vacancies in Cu-OCN catalysts facilitate CO2 electroreduction to C2H4.

Controllable morphology engineering of Cu2O nanoparticles for non-enzymatic glucose sensing

The controllable morphology engineering of active electrode materials is an effective strategy to obtain high performance non-enzymatic glucose sensing. Herein, different morphologic cuprous oxide (Cu2O nanospheres, nanocubes and microcubes) were controllably prepared by wet-chemistry precipitation technique through adjusting the OH– concentration. The growth and evolution mechanism of Cu2O at different OH– concentrations were extensively studied. Electrochemical testing revealed that Cu2O nanospheres had the highest sensitivity of 1438 μA mM−1 cm−2 and the lowest detection limit of 0.17 μM (S/N = 3), making them the best choice for glucose sensing. Additionally, the glucose detection range spanned two orders of concentration magnitude (0.5 μM ∼ 1.332 mM and 1.332 mM ∼ 3.832 mM), and the sensor displayed excellent anti-interference ability, reproducibility, and long-term stability. The electrode material also performed well in detecting glucose in real serum samples, indicating its practical applicability as a non-enzymatic sensor.

Macro-superlubricity in sputtered MoS2-based films by decreasing edge pinning effect

AbstractTo date, MoS2 can only be achieved at microscale. Edge pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to macroscale. Herein, we plan to pin edge planes of MoS2 with nanospheres, and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce friction. The sputtered MoS2 film was prepared by the physical vapor deposition (PVD) in advance. Then enough Cu2O nanospheres (∼40 nm) were generated in situ at the edge plane of MoS2 layers by liquid phase synthesis. An incommensurate structure (mismatch angle (θ) = 8°) caused by MoS2 layers was formed before friction. The friction coefficient of the films (5 N, 1,000 r/min) was ∼6.0×10−3 at the most. During friction, MoS2 layers pinned on numerous of Cu2O nanoparticles reduced its edge pinning effect and decreased friction. Moreover, much more incommensurate was formed, developing macro-superlubricity.

Construction of Cu2O single crystal nanospheres coating with brilliant structural color and excellent antibacterial properties

Structural coloration as a novel eco-friendly coloring method without using chemical dyes or pigments has been extensively studied for textile coloring. However, structural colors in creatures not only endow them with vivid colors, but also give them special functions. Therefore, the development of functional structural colored textiles with brilliant colors and special functions will have more practical application values. In this study, the structural colored and functional textiles were prepared by one-step spray coating cuprous oxide (Cu2O) single crystal nanospheres on polyethylene terephthalate (PET) fabric. Cu2O single crystal nanospheres with five different diameters were prepared to obtain purple, blue, green, yellow-green and orange noniridescent structural colors due to the Mie scattering of Cu2O nanospheres. Cu2O structural colored fabric showed excellent washing, rubbing and bending colorfastness due to the strong adhesion of polyacrylate (PA). Cu2O structural colored fabric showed excellent antibacterial properties for both Gram-positive and Gram-negative bacteria. The antibacterial rates of Cu2O structural colored fabric after treatment with 60 min for E. coli and S. aureus were close to 100%. Therefore, this research provides the experimental basis for the development of functional structural colored fabrics with brilliant color and excellent antibacterial properties.

Superhydrophobic and Conductive Wire Membrane for Enhanced CO2 Electroreduction to Multicarbon Products

AbstractGas‐liquid‐solid triple‐phase interfaces (TPI) are essential for promoting electrochemical CO2 reduction, but it remains challenging to maximize their efficiency while integrating other desirable properties conducive to electrocatalysis. Herein, we report the elaborate design and fabrication of a superhydrophobic, conductive, and hierarchical wire membrane in which core–shell CuO nanospheres, carbon nanotubes (CNT), and polytetrafluoroethylene (PTFE) are integrated into a wire structure (designated as CuO/F/C(w); F, PTFE; C, CNT; w, wire) to maximize their respective functions. The realized architecture allows almost all CuO nanospheres to be exposed with effective TPI and good contact to conductive CNT, thus increasing the local CO2 concentration on the CuO surface and enabling fast electron/mass transfer. As a result, the CuO/F/C(w) membrane attains a Faradaic efficiency of 56.8 % and a partial current density of 68.9 mA cm−2 for multicarbon products at −1.4 V (versus the reversible hydrogen electrode) in the H‐type cell, far exceeding 10.1 % and 13.4 mA cm−2 for bare CuO.

Superhydrophobic and Conductive Wire Membrane for Enhanced CO2 Electroreduction to Multicarbon Products.

Gas-liquid-solid triple-phase interfaces (TPI) are essential for promoting electrochemical CO2 reduction, but it remains challenging to maximize their efficiency while integrating other desirable properties conducive to electrocatalysis. Herein, we report the elaborate design and fabrication of a superhydrophobic, conductive, and hierarchical wire membrane in which core-shell CuO nanospheres, carbon nanotubes (CNT), and polytetrafluoroethylene (PTFE) are integrated into a wire structure (designated as CuO/F/C(w); F, PTFE; C, CNT; w, wire) to maximize their respective functions. The realized architecture allows almost all CuO nanospheres to be exposed with effective TPI and good contact to conductive CNT, thus increasing the local CO2 concentration on the CuO surface and enabling fast electron/mass transfer. As a result, the CuO/F/C(w) membrane attains a Faradaic efficiency of 56.8 % and a partial current density of 68.9 mA cm-2 for multicarbon products at -1.4 V (versus the reversible hydrogen electrode) in the H-type cell, far exceeding 10.1 % and 13.4 mA cm-2 for bare CuO.

A novel synthesis strategy for hybrid quaternary rGO/MnO2/NiO/CuO nanocomposite as electrode for enduring symmetric supercapacitor fabrication

Supercapacitors are one of the emerging energy devices due to the evolution in modern technologies which involve fast charging mechanisms with long-lasting stability and good retentivity. A hybrid quaternary composite of transition metal oxide consisting of MnO2, NiO, CuO nanospheres and reduced graphene oxide (rGO) was synthesized by a fusion method with enhanced supercapacitive behaviour. This nanocomposite was subjected to various structural, functional, morphological and electrochemical characterizations and further fabricated into a symmetric supercapacitor with benefiting and facile design. The electrochemical studies were carried out under electrolytes with different pH and mole concentrations both under 3-electrode and 2-electrode systems. The highest specific capacitance of 816.51 F/g was obtained with energy and power densities of 72.57 W h/kg and 0.5 kW/kg. The highest power density of 2.5 kW/kg was achieved corresponding to the current density of 5 A/g. Excellent cyclic retention of 86.46% was achieved after 5000 cycles proving long-term cyclic stability under 1 M KOH. Unfolding the nanocomposite to be a virtuous reference for supercapacitors’ future.

Electronic/ionic engineering inspired formation of carbon-encapsulated Cu3PSe4/Cu2Se heterostructured hollow nanosphere for trace level neurochemical monitoring

Exploring metal phosphorus chalcogenides (MPCs) with controllable structure and identified composition for capable of delivering an efficient and reliable sensor on tracking DA in body fluids is crucially challenging and desirable for biomedical research. Currently, we delicately adopt well-defined solid Cu2O nanospheres as initial template and PDA-derived carbon layer as supported skeleton for producing a 3D hollow Cu3PSe4/Cu2Se@C heterostructure nanospheres, which exhibits enhanced electrochemical sensing properties for catalyzing DA, especially its low detection limit and high sensitivity, as compared to its counterparts of Cu3PSe4/Cu2Se and Cu2Se, while it also equipped with powerful selectivity, stability, reproductivity and repeatability. All the excellent catalytic abilities are profited from, on the one hand, the formation of Cu3PSe4 makes the redistribution of the electrons and lower redox potential, on the other hand, the existence of carbon layer maintains a 3D hollow structure and reinforces electric conductivity. More intriguingly, acceptable accuracy evidenced the high reliability and wide feasibility of our Cu3PSe4/Cu2Se@C sensor for complex biological sample. Thus, future studies will focus on the fabrication of more MPXs compounds as functional electrocatalysts in response to diversified health issues.

Controllable Fabrication of CuO Nanostructures on Nickel Foam by Electrodeposition Method for High-Performance Supercapacitors

Two kinds of CuO nanomaterials with different morphologies were grown directly on surface of nickel foam using electrochemical deposition technology, and their electrochemical properties were studied. The morphology of CuO at different deposition voltages (spherical and wheat spike) were observed by field emission scanning electron microscopy. The results showed that the deposition voltage is the main factor affecting the morphology of CuO. In addition, X-ray diffraction results showed that the prepared samples are CuO materials. The electrochemical properties of CuO nanostructures were studied by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy. These test results showed that the specific capacitance of CuO nanomaterials was largely related to the morphology of the material. Compared with CuO nanospheres thin films, wheat spike CuO thin films had a more prominent specific capacitance. The wheat spike CuO array film has a specific capacitance of 120[Formula: see text]mF/cm2 at a current density of 1[Formula: see text]mA/cm2 in 1[Formula: see text]mol/L sodium sulfate electrolyte.