CuxO decorated Ti3C2Tx MXene composites for non-enzymatic glucose sensing with large linear ranges.

Ti3C2Tx MXene/CuxO composites were prepared by acid etching combined with electrochemical technique. The abundant active sites on the surface of MXene greatly increase the loading of CuxO nanoparticles, and the synergistic effect between the different components of the composite can accelerate the oxidation reaction of glucose. The results indicate that at the working potential of 0.55 V (vs. Ag/AgCl), the glucose sensor based on Ti3C2Tx MXene/CuxO composite presents large linear concentration ranges from 1 µM to 4.655 mM (sensitivity of 361 µA mM-1 cm-2) and from 5.155 mM to 16.155 mM (sensitivity of 133 µA mM-1 cm-2). The limit of detection is 0.065 µM. In addition, the sensor effectively avoids the oxidative interference of common interfering species such as ascorbic acid, dopamine and uric acid. The sensor has good reproducibility, stability and acceptable recoveries for the detection of glucose in human sweat sample (97.5-103.3%) with RSD values less than 4%. Based on these excellent properties it has great potential for the detection of glucose in real samples.

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction.

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10 nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75 µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

In Situ Probing of CO2 Reduction on Cu-Phthalocyanine-Derived Cux O Complex.

An in situ measurement of a CO2 reduction reaction (CO2 RR) in Cu-phthalocyanine (CuPC) molecules adsorbed on an Au(111) surface is performed using electrochemical scanning tunneling microscopy. One intriguing phenomenon monitored in situ during CO2 RR is that a well-ordered CuPC adlayer is formed into an unsuspected nanocluster via molecular restructuring. At an electrode potential of -0.7 V versus Ag/AgCl, the Au surface is covered mainly with the clusters, showing restructuring-induced CO2 RR catalytic activity. Using a measurement of X-ray photoelectron spectroscopy, it is revealed that the nanocluster represents a Cu complex with its formation mechanism. This work provides an in situ observation of the restructuring of the electrocatalyst to understand the surface-reactive correlations and suggests the CO2 RR catalyst works at a relatively low potential using the CuPC-derived Cu nanoclusters as active species.

In situ formation of CuxO/ZnO photocatalysts for efficient simultaneous oxidation of As (III) and adsorption of As (V): Effect of Cu loading.

The introduction of Cu ions onto ZnO leads to alterations in the electrical, optical, and magnetic characteristics of ZnO. These transformations, in turn, result in heightened photocatalytic activity and enhanced stability when employed in the degradation of both organic and inorganic pollutants. Here, a novel photocatalytic-adsorbent system is developed using zinc oxide (ZnO) nanostructures modified with Cu (II) ions in an aqueous solution containing 40 mg/L of As (III). The system utilizes UV-A light (365 nm) as the irradiation source, and the weight percentage of Cu (II) in the composite varies from 0 to 20%. The experimental results reveal significant adsorption of As (III), ranging from 20 to 50%, depending on the solution's Cu (II) content. Remarkably, the ZnO10%Cu composite exhibits the highest photocatalytic activity, achieving 40% adsorption and complete oxidation of As (III) within 25 min of irradiation. Characterization of the composite after the photocatalytic treatment reveals the effective adsorption of As (V) within its structure. Furthermore, no traces of Cu (II) ions are detected in the solution after the reaction, indicating their successful adsorption onto the ZnO surface as Cu (I) and Cu (II) ions. This research marks a significant advancement in harnessing innovative materials for efficient arsenic removal, offering promising insights into the development of novel photocatalytic-adsorbent systems.

Formation and Characterization of Stable TiO2/CuxO-Based Solar Cells.

According to increasing demand for energy, PV cells seem to be one of the best answers for human needs. Considering features such as availability, low production costs, high stability, etc., metal oxide semiconductors (MOS) are a focus of attention for many scientists. Amongst MOS, TiO2 and CuxO seem to be promising materials for obtaining an effective photoconversion effect. In this paper, specific investigation, aimed at the manufacturing of the complete photovoltaic structure based on this concept is described in detail. A set of samples manufactured by DC magnetron sputtering, with various process parameters, is characterized by morphology comparison, layer structure and material composition investigation, and finally by the obtained photovoltaic parameters. Based on SEM studies, it was established that the films are deposited uniformly and complete their formation; without clearly defined faces, the conglomerates of the film grow individually. These are areas with a uniform structure and orientation of atoms. The sizes of conglomerates are in a normal direction range from 20 to 530 nm and increase with film thickness. The film thickness was in the range from 318 to 1654 nm, respectively. The I-V study confirms the photovoltaic behavior of thin film solar cells. The open-circuit voltage (Voc) and short-circuit current density (Jsc) values of the photovoltaic devices ranged from 1.5 to 300 mV and from 0.45 to 7.26 µA/cm3, respectively, which corresponds to the maximum efficiency at the level of 0.01%. Specific analysis of the junction operation on the basis of characteristics flow, Rs, and Rsh values is delivered.

Lithiophilic Interface Layer Induced Uniform Deposition for Dendrite-free Lithium Metal Anodes in a 3D Polyethersulfone Frame.

Lithium metal anodes possess ultrahigh theoretical specific capacity for next-generation lithium metal batteries, but the infinite volume expansion and the growth of lithium dendrites remain a huge obstacle to their commercialization. Therefore, here, we construct a CuO-loaded 3D polyethersulfone (PES) nanofiber frame onto a lithiophilic Cu2O/Cu substrate to promote the lithium storage performance of the composite anode, and the 3D frame can effectively alleviate the volume expansion of lithium (Li) metal anodes. Meanwhile, lithium reacts with CuO in the composite nanofiber and Cu2O of the substrate to generate Li2O, which can strengthen the solid electrolyte interface (SEI) layer and achieve the uniform deposition of lithium. In addition, the combination of the heat treatment method and electrospinning technology solves the problem of poor adhesion between the fiber film and the substrate. As a result, the PES/CuO-Cu2O (PCC) composite current collector still maintains a smooth and flat lithium-depositing layer at 5 mA cm-2. The PCC-assembled Li||Cu half-cell can operate stably for 320 cycles at 0.5 mA cm-2, which is about 4 times that of bare Cu. Furthermore, symmetrical batteries with PCC@Li can maintain excellent cycle stability for 1770 h. Accordingly, this work provides a low-cost and highly effective strategy for stabilizing the lithium metal anode.

Effective degradation of tetracycline via recyclable free-standing three-dimensional copper-based graphene as a persulfate catalyst.

Water pollution by antibiotics is a serious and growing problem. Given this challenge, a free-standing three-dimensional (3D) reduced graphene oxide foam supported copper oxide nanoparticles (3D-rGO-CuxO) was synthesized using GO as a precursor and applied as an efficient persulfate activator for tetracycline (TC) degradation. The influences of CuxO mass, solution pH, persulfate dosage, and common anions on the TC degradation were investigated in detail. Analytical techniques indicated that the 3D-rGO-CuxO showed a cross-linking three-dimensional network structure, and CuxO particles with irregular shapes were uniformly loaded on graphene pore walls. The XPS and Auger spectra of Cu confirmed that Cu2O was the main component in solid copper compounds. The addition of CuxO was vitally important for the activation of the oxidation system, and the removal rate reached 98% with a CuxO load of 7:1. The pH showed little influence on the activation effect on TC degradation. For common anions, Cl- and CO32- had little influence on the system, while humic acid had a great inhibitory effect. The EPR test and quenching experiment revealed that the active substances in the oxidative degradation process mainly include SO4-·, ·OH, 1O2, and reactive Cu(III). Additionally, the 3D-rGO-CuxO material proved highly stable according to the replicated test results and was promising for the remediation of antibiotic-contaminated water.

Insight into radical-nonradical coupling activation pathways of peroxymonosulfate by CuxO for antibiotics degradation.

In this work, a heterogeneous catalyst of CuxO was rationally designed by using Cu-based metal organic frameworks (marked Cu-BDC) as the template, and was used to degrade tetracycline (TC) via activation of peroxymonosulfate (PMS). The optimal CuxO-350 showed excellent catalytic efficiency for TC degradation, and the reaction rate constant (0.104 min-1) was 8 times higher than that (0.013 min-1) of raw Cu-BDC. The characterization observations confirmed that CuxO-350 possessed multiple valence states (CuO and Cu2O) and oxygen vacancies (Ov), both of which were favorable for the activation of PMS, resulting in promoting the generation of active species in the CuxO-350 + PMS system. Different from the free radical pathway in Cu-BDC + PMS system, a radical-nonradical coupling process was detected in the CuxO-350 + PMS system, which was confirmed by quenching experiments and EPR measurements. Moreover, the toxicity prediction showed that the toxicity of degradation intermediates declined compared with TC. This work not only opened up a new strategy for the rational design and preparation of high-efficient catalysts by employing metal organic frameworks precursors, but also offered an insight into the reaction mechanism of PMS activation through a radical-nonradical coupling process catalyzed by CuxO-350 derived from Cu-BDC.

Enhanced Visible-Light-Responsive Photocatalytic Degradation of Ciprofloxacin by the CuxO/Metal-Organic Framework Hybrid Nanocomposite.

Ciprofloxacin (CIP) is a commonly used antibiotic, however, once in the environment, it is highly toxic with a poor biodegradability. Given these attributes, an effective strategy for the removal of CIP is urgently needed for the protection of water resources. Herein, a novel copper metal-organic framework (CuxO/MOF) multifunctional material has been produced, in this work, by the calcination of Cu-MOF urea at 300 °C, in the presence of a 5% H2 atmosphere. The morphological, structural, and thermal properties of the prepared CuxO/MOF were determined through various techniques, and its photocatalytic behavior was investigated for the degradation of CIP under visible-light irradiation. The prepared CuxO/MOF bifunctional material is presented as a graphitic carbon-layered structure with a particle size of 9.2 ± 2.1 nm. The existence of CuO-Cu2O-C, which was found on the CuxO/MOF surface, enhanced the adsorption efficiency and increased the photosensitivity of CuxO/MOF, towards the degradation of CIP in aqueous solutions. The tailored CuxO/MOF, not only shows an excellent CIP degradation efficiency of up to 92% with a constant kinetic rate (kobs) of 0.048 min−1 under visible light, but it can also retain the stable photodegradation efficiency of >85%, for at least six cycles. In addition, CuxO/MOF has an excellent adsorption capacity at pH 6.0 of the maximum Langmuir adsorption capacity of 34.5 mg g−1 for CIP. The results obtained in this study demonstrate that CuxO/MOF is a reliable integrated material and serves as an adsorbent and photocatalyst, which can open a new pathway for the preparation of visible-light-responsive photocatalysts, for the removal of antibiotics and other emerging pollutants.

Selective Oxygen Activation to Reactive Oxygen Species on a Carbon Layer-Encapsulated CuxO Electrocatalyst for Water Purification.

In situ synthesis of reactive oxygen species (ROS) on demand via oxygen activation (OA) is significant in biological, chemical, and environmental fields. Thus, the design of OA catalysts with adequate reactivity, durability, and selectivity is critical but challenging. Here, we report a CuxO@C core@shell photoelectrode prepared by encapsulating Cu/Cu2O/CuO into a carbon layer through anodic electropolymerization (electrophoresis-coupled self-assembly of carbon quantum dots). Theoretical prediction and experiments indicate that the carbon layer can effectively facilitate optical trapping and charge transfer, thus promoting photoelectric conversion and anti-photocorrosion performance of CuxO@C. The inner CuxO core acts as an electron reservoir and continuously injects electrons into the outer carbon layer shell, and the carbon atoms adjacent to oxygen-enriched functional groups (C-O-C and -COOH) in the electron-rich carbon layer work as the reactive sites to adsorb O2 and donate electrons to the antibonding orbital [lowest unoccupied molecular orbital (π*)] of dioxygen. Optimized adsorption and hydrogenation of the critical intermediates (*O2, *OOH, and *H2O2) and thermodynamically tunable O-O bond cleavage enable O2 being selectively reduced to the superoxide anion and hydroxyl radical via the mixed multielectron processes consisting of one- and three-electron pathways. Sulfamethoxazole, an emerging refractory organic contaminant widely present in the environment, can be effectively degraded (∼100% removal) in such an electrochemical platform, benefiting from the abundant ROS generated in situ. Our findings demonstrate an innovative strategy to develop highly efficient and selective OA catalysts for practical water purification.

CuxO nanorod arrays shelled with CoNi layered double hydroxide nanosheets for enhanced oxygen evolution reaction under alkaline conditions.

Exploration of highly efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is of crucial importance for the development of water splitting. In recent years, Cu-based materials have been widely concerned in OER due to their non-toxicity, rich reserves and highest reversibility. Meanwhile, CuxO nanorods is easy to be prepared in industry. Herein, we report a fast preparation method to construct an integrated CuxO@CoNi-LDH electrocatalyst with a unique 1D nanowire-2D nanosheet hierarchical core-shell structure by electrodepositing CoNi-LDH nanosheet arrays directly onto CuxO nanorods (CuxO were in situ-created on the Cu foam) at a large deposition voltage of -3.0 V vs SCE. The unique heterogeneous core-shell nanostructure, large deposition amount of CoNi-LDH and the synergistic effects between CuxO core and CoNi-LDH shell can provide abundant active sites, rich open-channels and reduced charge transfer resistance (Rct) for effective oxygen release and facile electron transport. Consequently, the optimized CuxO@CoNi-LDH/CF exhibits a low overpotential of 207 mV in 1 M KOH solution at the current density of 10 mV cm-2 and a small Tafel slope of 50.1 mV dec-1. After 60 h of long-term stability test, the catalytic performance is only slightly weakened. This work demonstrates a new approach to design the high-performance LDH and Cu-related OER catalysts by constructing a unique hierarchical core-shell nanostructure.

Photoelectron Properties and Organic Molecules Photodegradation Activity of Titania Nanotubes with CuxO Nanoparticles Heat Treated in Air and Argon.

Titania is very famous photocatalyst for decomposition of organic pollutants. Its photocatalytic properties significantly depend on the morphology and chemical composition of the samples. Herein, the TiO2 nanotubes/CuxO nanoheterostructures have been synthesized and the effect of heat treatment performed in molecular atmospheres of air and argon on their photoelectrochemical and photocatalytic properties has been studied. The prepared samples have a higher reaction rate constant compared to TiO2 nanotubes in the decomposition reaction of methylene blue molecules. It is established that in argon treated nanoheterostructures, the copper oxide is present in two phases, CuO and Cu2O, while in air treated ones there is only CuO. In the TiO2 nanotubes/CuxO samples, Cu2+ ions and molecular O2- radicals were detected while in TiO2 nanotubes only carbon dangling bond defects are present. The dynamics of O2- radicals under illumination are discussed. It was shown that the TiO2 nanotubes do not exhibit photocatalytic activity under visible light. The mechanism of the photocatalytic reaction on the surface of the TiO2 nanotubes/CuxO samples was proposed. It is assumed that a photocatalytic decomposition of organic molecules under visible light at the surface of the nanoheterostructures under investigation is realized mainly by the reaction of these molecules with photogenerated O2- radicals. The results obtained are completely original and indicate the high promise of the prepared photocatalysts.

Enhanced Photocatalytic Hydrogen Evolution from Water Splitting on Ta2O5/SrZrO3 Heterostructures Decorated with CuxO/RuO2 Cocatalysts.

Photocatalytic H2 generation by water splitting is a promising alternative for producing renewable fuels. This work synthesized a new type of Ta2O5/SrZrO3 heterostructure with Ru and Cu (RuO2/CuxO/Ta2O5/SrZrO3) using solid-state chemistry methods to achieve a high H2 production of 5164 µmol g-1 h-1 under simulated solar light, 39 times higher than that produced using SrZrO3. The heterostructure performance is compared with other Ta2O5/SrZrO3 heterostructure compositions loaded with RuO2, CuxO, or Pt. CuxO is used to showcase the usage of less costly cocatalysts to produce H2. The photocatalytic activity toward H2 by the RuO2/CuxO/Ta2O5/SrZrO3 heterostructure remains the highest, followed by RuO2/Ta2O5/SrZrO3 > CuxO/Ta2O5/SrZrO3 > Pt/Ta2O5/SrZrO3 > Ta2O5/SrZrO3 > SrZrO3. Band gap tunability and high optical absorbance in the visible region are more prominent for the heterostructures containing cocatalysts (RuO2 or CuxO) and are even higher for the binary catalyst (RuO2/CuxO). The presence of the binary catalyst is observed to impact the charge carrier transport in Ta2O5/SrZrO3, improving the solar to hydrogen conversion efficiency. The results represent a valuable contribution to the design of SrZrO3-based heterostructures for photocatalytic H2 production by solar water splitting.

Charge-Switchable CuxO Nanozyme with Peroxidase and Near-Infrared Light Enhanced Photothermal Activity for Wound Antibacterial Application.

Bacterial infection is still a thorny problem threatening human health, and nanozymes offer a promising alternative strategy to combat the health threat posed by bacterial infection. However, the antibacterial efficacies of nanozymes are unsatisfactory because of low catalytic activity of nanozymes and their inability to trap bacteria. Herein, a multifunctional nanozyme, polydopamine (PDA)-modified copper oxide (CuxO-PDA) is designed to overcome this challenge. CuxO-PDA showed peroxidase-mimicking activity and the catalytic activity was enhanced upon near-infrared (NIR) irradiation. CuxO-PDA was negatively charged under neutral or alkaline condition and showed no obvious peroxidase-mimicking activity. On the contrary, the surface charge of CuxO-PDA can be switched to positive under acidic conditions, which can target negatively charged bacteria. More interestingly, well-dispersed CuxO-PDA can aggregate rapidly under NIR irradiation, which trapped the bacteria and nanozymes together. It was found that shortening the distance between nanozyme and bacteria could improve the antibacterial effect. The obtained CuxO-PDA can cause DNA degradation, lipid peroxidation, and biofilm eradication. CuxO-PDA showed good antibacterial effect against two kinds of representative bacteria, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The experiment in vivo further proved favorable antibacterial activity of CuxO-PDA nanozyme.

An electrochemical amplification strategy based on the ferrocene functionalized cuprous oxide superparticles for the detection of NSE.

A sandwich-type electrochemical immunosensor was designed utilizing ferrocene-functionalized cuprous oxide superparticles (Au/Fc@CuxO SPs) as the signal label and graphene supported by hollow carbon balls (HCNs-GR) as the substrate. The CuxO SPs possess a superparticle structure with synergistic properties of isotropy and promising catalytic activity. Ferrocene (Fc) was deposited on the CuxO SPs to act as the electronic transmission medium. The Au/Fc@CuxO SPs played a pivotal role in improving the sensitivity of the immunosensor. The graphene supported by hollow carbon balls (HCNs-GR) was used to modify the electrode surface. The embedding of hollow carbon nanospheres (HCNs) reduced the decrease of the effective surface area caused by the stacking of graphene nanotubes. Meanwhile, the load of carbon balls further increases the surface area of graphene, enabled HCNs-GR to immobilize antibodies more effectively, improved the sensitivity of the immunosensor. The proposed immunosensor showed a linear range from 500 fg/mL to 100 ng/mL, with the detection limit to 25.7 fg/mL.

Mo and Zn-Dual doped CuxO nanocrystals confined High-Conductive Cu arrays as novel sensitive sensor for neurotransmitter detection.

The development of sensitive and selective sensors using facile and low-cost methods for detecting neurotransmitter molecules is a critical factor in the health care system in regard to early diagnosis. In this research, an electrocatalyst derived from Mo,Zn dual-doped CuxO nanocrystals-based layer coating over one-dimensional copper nanowire arrays (Mo,Zn-CuxO/CuNWs) was successfully designed using a facile electrodeposition approach and used as an electrochemical sensor for non-enzymatic dopamine (DA) neurotransmitter detection. The synergistic effect caused by the dual-doping effect along with its excellent conductivity produced a large electroactive surface area and an improved hetero-charge transfer, thereby boosting DA sensing ability with a low limit detection of 0.32 µM, wide-range of detection (0.5 µM - 3.9 mM), long-term stability (5 weeks), and high selectivity in phosphate buffer solution (pH 7.4). Also, the sensor accurately determined DA in real blood serum-spiked solutions. The achieved results evidenced that the Mo,Zn-CuxO/CuNWs derived sensor is highly suitable for DA detection. Therefore, it also opens new windows for the development of low-cost, accurate, high-performance, and stable sensors for other neurotransmitter sensing for the purposes of better health care and early diagnosis.

CuxO nanorods with excellent regenerable NADH peroxidase mimics and its application for selective and sensitive fluorimetric ethanol sensing.

CuxO nanorods with excellent NADH peroxidase mimics were synthesized by a simple hydrothermal method. The catalytic oxidation of NADH to NAD cofactor strictly follows the enzymatic kinetics with high catalytic rate and strong affinity. The catalytic mechanism of CuxO NRs was that in the presence of hydrogen peroxide, the catalytic oxidizing NADH to NAD + involving with O2.-.anion production, making it realistic to mutually convert between coenzymes. Considering that the mutual transformation of NADH/NAD cofactors plays an important role in biological function, combination of CuxO NRs with alcohol dehydrogenase, a highly selective method for fluorimetric detection of ethanol was established. The as-proposed sensing platform is capable of dectecting alcohol with the limit of detection of 26.7 µM (S/N = 3) and applied in practical sample with satisfied accuracy and recovery. The as-developed regenerable NADH peroxidase mimics would also cast lights in biocatalysis, synthetic biology and bioenergy.

Formulating Multiphase Medium Anti-wetting States in an Air-Water-Oil System: Engineering Defects for Interface Chemical Evolutions.

Studies which regulate macroscopic wetting states on determined surfaces in multiphase media are of far-reaching significance but are still in the preliminary stage. Herein, inspired by the wettability subassembly of fish scales, Namib desert beetle shell, and lotus leaf upper side, interfaces in the air-water-oil system are programmed by defect engineering to tailor the anti-wetting evolution from double to triple liquid repellency states. By controlling the visible light irradiation and plasma treatment, surface oxygen vacancies on CuxO@TiO2 nanowires (NWs) can be healed or reconstructed. The original membrane or the membrane after plasma treatment possesses abundant surface oxygen vacancies, and the homogeneous hydrophilic membrane shows only double anti-wetting states in the water-oil system. By the unsaturated visible light irradiation time, the surface oxygen vacancy partially healed, the heterogeneous hydrophilic-hydrophobic components occupied the membrane surface, and the anti-wetting state finally changed from double to triple in the air-water-oil system. After the illumination time reaches saturation, it promotes the healing of all surface oxygen vacancies, and the membrane surface only contains uniform hydrophobic components and only maintains double anti-wetting state in the air-oil system. The mechanism of the triple anti-wetting state on a heterogeneous surface is expounded by establishing a wetting model. The wetting state and the adhesion state of the CuxO@TiO2 NW membrane show regional specificity by controlling the illumination time and region. The underwater oil droplets exhibit the "non-adhesive" and "adhesive" state in a region with unsaturated irradiation time or in an unirradiated region, respectively. Underwater oil droplet manipulation can be accomplished easily based on switchable wettability and adhesion. Current studies reveal that defect engineering can be extended to anti-wetting evolution in the air-water-oil system. Constructing an anti-wetting interface by heterogeneous components provides reference for designing the novel anti-wetting interface.

Synthesis and characterization of CuxO/Bi2O3 oxides for removal of HCHO under visible light irradiation.

CuxO/Bi2O3 oxides grown on nickel foam were synthesized via an electrodeposition method to degrade indoor HCHO under visible light irradiation and fully characterized by XRD, SEM, FT-IR, and UV-Vis technologies. The characterization results showed that the CuxO/Bi2O3 oxides were successfully loaded on nickel foam and the visible light response spectrum was expanded to 740 nm. Plackett-Burman design combined with central composite design has been used to optimize factors that affect HCHO removal performance. The results demonstrated that bismuth nitrate content, polyethylene glycol 600 content, sintering time, and lactic acid concentration were the four most important factors affecting the HCHO removal performance over CuxO/Bi2O3 sample. The optimum CuxO/Bi2O3 sample could degrade 88.796% of HCHO in 300 min at the conditions of 4.28 mol/L lactic acid, 4.86% polyethylene glycol 600, 194.03 min sintering time, and 45.83 g bismuth nitrate, and the HCHO removal rate remained 82.3% after five cycles. A plausible mechanism for the degradation of HCHO under visible light irradiation was proposed. This work provides a feasible solution for removing indoor formaldehyde in the field of photocatalysis.

Flexible Free-Standing CuxO/Ag2O (x = 1, 2) Nanowires Integrated with Nanoporous Cu-Ag Network Composite for Glucose Sensing.

To improve glucose electrocatalytic performance, one efficient manner is to develop a novel Cu-Ag bimetallic composite with fertile porosity and unique architecture. Herein, the self-supported electrode with CuxO/Ag2O (x = 1, 2) nanowires grown in-situ on a nanoporous Cu-Ag network (CuxO/Ag2O@NP-CuAg) has been successfully designed by a facile two-step approach. The integrated hierarchical porous structure, the tip-converged CuxO/Ag2O nanowires combined with the interconnected porous conductive substrate, are favorable to provide more reactive sites and improve ions or electrons transportation. Compared with monometallic Cu2O nanowires integrated with nanoporous Cu matrix (Cu2O@NP-Cu), the bimetallic CuxO/Ag2O@NP-CuAg composites exhibit the enhanced electrocatalytic performance for glucose. Moreover, the higher sensitivity of ~1.49 mA mM-1 cm-2 in conjunction with a wider linear range of 17 mM for the CuxO/Ag2O@NP-CuAg electrode anodized for 10 min are attributed to the synergistic effect of porous structure and bimetallic CuxO/Ag2O nanowires. Particularly, the integrated CuxO/Ag2O@NP-CuAg composites possess good flexibility, which has been reported for the first time. Accordingly, the CuxO/Ag2O@NP-CuAg with excellent glucose electrocatalytic performance and good flexibility is promising to further develop as a candidate electrode material of glucose sensors.