Effect of temperature on the oxidation of Cu nanowires and development of an easy to produce, oxidation-resistant transparent conducting electrode using a PEDOT:PSS coating

Copper nanocubes as low-cost enzyme mimics in a sarcosine-sensing reaction cascade

The development of simple, inexpensive, deployable clinical diagnostics could have a global impact on public health by making measurements of patient health status more widely accessible to patients regardless of socioeconomic status. Here, we report a novel biosensor for sarcosine using a colorimetric readout created by a hybrid catalyst system using copper nanocubes and the enzyme sarcosine oxidase. The enzyme catalyzes the reaction of sarcosine to generate H2O2, which the copper nanocubes then use as a substrate to create free radicals that convert colorless 3,3',5,5'-tetramethylbenzidine (TMB) to its blue, oxidized form. The sensor showed good substrate affinity for Cu nanocubes and yielded a wide linear response range (0-140 μM) for sarcosine detection, with high selectivity against various interfering species. The limit of detection and limit of quantification were found to be 1.43 μM and 4.7 μM, respectively. We showed that the biosensor maintains function in a complex serum sample matrix, suggesting potential utility in clinical applications. Finally, we demonstrated a prototype based on light emitting diodes (LEDs) and a light-dependent resistor (LDR) for unambiguous visual interpretation using an inexpensive microcontroller potentially suitable for use outside of traditional clinical or analytical laboratories.

Laser writing of metal-oxide doped graphene films for tunable sensor applications

Flexible and wearable devices play a pivotal role in the realm of smart portable electronics due to their diverse applications in healthcare monitoring, soft robotics, human-machine interfaces, and artificial intelligence. Nonetheless, the extensive integration of intelligent wearable sensors into mass production faces challenges within a resource-limited environment, necessitating low-cost manufacturing, high reliability, stability, and multi-functionality. In this study, a cost-effective fiber laser direct writing method (fLDW) was illustrated to create highly responsive and robust flexible sensors. These sensors integrate laser-induced graphene (LiG) with mixed metal oxides on a flexible polyimide film. fLDW simplifies the synthesis of graphene, functionalization of carbon structures into graphene oxides and reduced graphene oxides, and deposition of metal-oxide nanoparticles within a single experimental laser writing setup. The preparation and surface modification of dense oxygenated graphene networks and semiconducting metal oxide nanoparticles (CuO x , ZnO x , FeO x ) enables rapid fabrication of LiG/MO x composite sensors with the ability to detect and differentiate various stimuli, including visible light, UV light, temperature, humidity, and magnetic fluxes. Further, this in situ customizability of fLDW-produced sensors allows for tunable sensitivity, response time, recovery time, and selectivity. The normalized current gain of resistive LiG/MO x sensors can be controlled between -2.7 to 3.5, with response times ranging from 0.02 to 15 s, and recovery times from 0.04 to 6 s. Furthermore, the programmable properties showed great endurance after 200 days in air and extended bend cycles. Collectively, these LiG/MO x sensors stand as a testament to the effectiveness of fLDW in economically mass-producing flexible and wearable electronic devices to meet the explicit demands of the Internet of Things.

Deciphering the Electronic Coupling Dynamics of Laser-induced Ru/Cu Electrocatalyst for Dual-Side Hydrogen Production and Formic Acid Co-synthesis via DFT Analysis

Herein, a straightforward approach using pulsed laser technology to synthesize selective hexagonal-close-packed (hcp) Ru nanoparticles attached to Cu nanospheres (Ru/Cu) as bifunctional electrocatalyst for catalyzing the hydrogen evolution reaction (HER) and formaldehyde oxidation reaction (FOR) are reported. Initially, Ru-doped CuO flakes are synthesized using a coprecipitation method followed by transformation into Ru/Cu composites through a strategy involving pulsed laser irradiation in liquid. Specifically, the optimized Ru/Cu-4 composite not only demonstrates a low overpotential of 182 mV at 10 mA·cm-2 for the HER but also an ultralow working potential of 0.078 V (versus reversible hydrogen electrode) for the FOR at the same current density. Remarkably, the FOR∥HER-coupled electrolyzer employing the Ru/Cu-4∥Ru/Cu-4 system achieves H2 production at both electrodes with a cell voltage of 0.42 V at 10 mA·cm-2 while co-synthesizing formic acid. Furthermore, density functional theory analyses elucidate that the superior activity of the Ru/Cu composite originates from optimized adsorption energies of reactive species on the catalyst surfaces during the HER and FOR, facilitated by the synergistic coupling between Ru and Cu. This study presents an alternative strategy for synthesizing highly effective electrocatalytic materials for use in energy-efficient H2 production with the cosynthesis of value-added chemicals suitable for practical applications.

Counteractive Effects of Copper Nanoparticles and Betacellulin on Ovarian Cells

Copper nanoparticles (CuNPs) are known to affect many ovarian cell functions. CuNPs, prepared using a chemical reduction method, were fully characterized by different means (TEM, DLS, XRD, Z potential, XPS, and AES). The resulting colloidal suspension contained needle-like CuNPs aggregates made of a core of metallic copper and an oxidized surface of Cu2O and CuO. The separate and coupled effects of CuNPs and the growth factor betacellulin (BTC) were analyzed on the control of some basic functions of ovarian cells. With this purpose, porcine ovarian granulosa cells, together with CuNPs, BTC, and both (CuNPs + BTC), were cultured. Viability and BrDU tests, quantitative immunocytochemistry, TUNEL, and ELISA were used to evaluate markers of the S-phase (PCNA) and G-phase (cyclin B1) of the cell cycle, cell proliferation (BrDU incorporation), cytoplasmic/mitochondrial apoptosis (bax) and extrinsic (nuclear DNA fragmentation) markers, and the release of estradiol and progesterone. CuNPs were accumulated within the cells and were found to reduce all the markers of proliferation, but promoted all the markers of apoptosis and the release of steroid hormones. When added alone, BTC raised the expression of all cell viability and proliferation markers, depleted the expression of all apoptosis markers, and stimulated the release of both estradiol and progesterone. Furthermore, BTC prevented and even reversed the effect of CuNPs on all the measured parameters, whereas CuNPs mitigated BTC's effect on all the analyzed cell functions. These results support a direct toxic effect of CuNPs and a stimulatory effect of BTC on ovarian cell functions, as well as the capability of BTC to protect against the adverse effects of CuNPs.

Exploring the catalytic potential of watermelon urease: Purification, biochemical characterization, and heavy metal precipitation

Bioactive urease from watermelon (Citrullus lanatus) seeds was purified using acetone fractionation, anion-exchange, and size-exclusion chromatography, achieving a 121-fold increase and specific activity of 3216 U/mg. The enzyme appeared as a single band on native and SDS-PAGE, with a molecular mass of 480 ± 10 kDa and subunit mass of 80 ± 10 kDa, indicating six identical subunits. Atomic absorption spectroscopy revealed 1.46 nickel ions per subunit. Watermelon urease exhibited serological similarities with jack bean and pigeon pea ureases, an optimal pH of 7.3, an activation energy of 3 kcal/mol, Vmax of 3571 μmol/min/mg, and Km of 0.16 mM. The enzyme displayed biphasic thermal and pH inactivation kinetics, a strong preference for urea, and a half-life of 70 days with 1 mM DTT. This study highlights watermelon urease's role in bioremediation by facilitating the precipitation of heavy metals as stable carbonates, promoting environmental sustainability.

Red Fluorescent Copper Nanoclusters for Fluorescence, Smartphone, and Electrochemical Sensor Arrays to Detect the Monkeypox A29 Protein

An Orthopox zoonotic viral infection called monkeypox (MPXV) is the leading infectious disease globally. MPXV can easily spread from human to human through direct and indirect sexual contact; therefore, accurate and early detection of MPXV is crucial for reducing mortality. Fluorescence-based materials have received significant attention in recent years for biomedical applications. In this study, we synthesized red-fluorescent copper nanoclusters (CuNCs) with a size of less than 10 nm, which was confirmed by high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (Bio-AFM) analysis. The synthesized CuNCs had a high fluorescence nature and were utilized for the detection of the MPXV (A29P) by an antigen-antibody conjugation using fluorescence, smartphone colorimetric, and electrochemical sensing techniques. The antigen (A29P) and antibody (Ab A29) interaction mechanisms were studied by X-ray photoelectron spectroscopic (XPS) analysis. Furthermore, fluorescence and electrochemical sensing were performed in PBS with detection limits of 0.096 and 0.114 nM, respectively. For real-world applications, the prepared immunosensor array can detect A29P in spiked serum samples, and point-of-care (POC) analysis, a smartphone-integrated sensor array, was used to measure the RGB color changes. The results showed that synthesized CuNCs are potential materials for detecting A29P via fluorescence and smartphone colorimetric and electrochemical sensing techniques.

The Dependence of NiMo/Cu Catalyst Composition on Its Catalytic Activity in Sodium Borohydride Hydrolysis Reactions

The production of high-purity hydrogen from hydrogen storage materials with further direct use of generated hydrogen in fuel cells is still a relevant research field. For this purpose, nickel-molybdenum-plated copper catalysts (NiMo/Cu), comprising between 1 and 20 wt.% molybdenum, as catalytic materials for hydrogen generation, were prepared using a low-cost, straightforward electroless metal deposition method by using citrate plating baths containing Ni2+-Mo6+ ions as a metal source and morpholine borane as a reducing agent. The catalytic activity of the prepared NiMo/Cu catalysts toward alkaline sodium borohydride (NaBH4) hydrolysis increased with the increase in the content of molybdenum present in the catalysts. The hydrogen generation rate of 6.48 L min-1 gcat-1 was achieved by employing NiMo/Cu comprising 20 wt.% at a temperature of 343 K and a calculated activation energy of 60.49 kJ mol-1 with remarkable stability, retaining 94% of its initial catalytic activity for NaBH4 hydrolysis following the completion of the fifth cycle. The synergetic effect between nickel and molybdenum, in addition to the formation of solid-state solutions between metals, promoted the hydrogen generation reaction.

Functionalization of Artwork Packaging Materials Utilizing Ag-Doped TiO2 and ZnO Nanoparticles

Most of the artworks stored in museums are often kept in inappropriate climatic and environmental conditions that facilitate the formation and growth of microorganisms, such as fungi, which are responsible for many types of biodegradation phenomena. To mitigate and prevent these deteriorative processes, functionalized packaging materials can be used for the storage and handling of artworks. The aim of this study was to develop a potential anti-biodeterioration coating suitable for packaging purposes. TiO2 and ZnO doped with different amounts of Ag (0.5 wt%, 1 wt%, and 3 wt%) were synthesized and dispersed in polyvinyl alcohol (PVA) and acrylic resin (Paraloid B72), then applied on different types of packaging materials (cellulose and the high-density spunbound polyethylene fiber Tyvek®, materials that are frequently used as packaging in museums). Analytical investigations (SEM/EDS, Raman, FTIR, and XRD) were employed to assess dispersion on the packaging material. Furthermore, resistance against biodeteriogens was assessed using Cladosporium sp., a bioluminometer, to define the biocidal efficacy.

Copper oxide(I) nanoparticle-modified cellulose acetate membranes with enhanced antibacterial and antifouling properties

Cellulose acetate membranes exhibit a potential to be applied in hemodialysis. However, their performance is limited by membrane fouling and a lack of antibacterial properties. In this research, copper oxide (I) nanoparticles were fabricated in situ into a cellulose acetate matrix in the presence of polyvinylpyrrolidone (pore-forming agent) and sulfobetaine (stabilising agent) to reduce the leakage of copper ions from nano-enhanced membranes. The influence of nanoparticles on the membrane structure and their antibacterial and antifouling properties were investigated. The results showed that incorporating Cu2O NPs imparted significant antibacterial properties against Staphylococcus aureus and fouling resistance under physiological conditions. The Cu2O NPs-modified membrane could pave the way for potential dialysis applications.

Synthesis rifaximin with copper (Rif-Cu) and copper oxide (Rif-CuO) nanoparticles Considerable dye decolorization: An application of aerobic oxidation of eco-friendly sustainable approach

In this study, rifaximin with copper (Cu) and copper oxide (CuO) nanoparticles (NPs) were synthesised. The resultant CuO nanoparticles were used to degrade Rhodamine B (RhB) and Coomassie Brilliant Blue (G250). Rifaximin copper and copper oxide nanoparticles were characterised using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), and gas chromatography-electrochemical mass spectrometry (GC-EI-MS). An FT-IR study confirmed the formation of Cu in the 562 cm-1 peak range. Rifaximin Cu and CuO Nanoparticles displayed UV absorption peaks at 253 nm and 230 nm, respectively. Coomassie Brilliant Blue G250 was completely decolourised in Cu nanoparticles at 100 %, and Rhodamine B was also decolourised in Rifaximin CuO nanoparticles at 73 %, although Coomassie Brilliant Blue G250 Rifaximin Cu nanoparticles absorbed a high percentage of dye decolorization. The aerobic oxidation of isopropanol conversion was confirmed by GC-MS analysis. Retention time of 27.35 and 30.32 was confirmed using Cu and CuO nanoparticles as the final products of 2-propanone. It is used in the textile and pharmaceutical industries for aerobic alcohol oxidation. Rifaximin CuO nanoparticles highly active in aerobic oxidation. The novelty of this study is that, for the first time, rifaximin was used for the synthesis of copper and copper oxide nanoparticles, and it successfully achieved decolorization and aerobic oxidation.

Highly Flexible and Acid-Alkali Resistant TiN Nanomesh Transparent Electrodes for Next-Generation Optoelectronic Devices

Transparent electrodes are vital for optoelectronic devices, but their development has been constrained by the limitations of existing materials such as indium tin oxide (ITO) and newer alternatives. All face issues of robustness, flexibility, conductivity, and stability in harsh environments. Addressing this challenge, we developed a flexible, low-cost titanium nitride (TiN) nanomesh transparent electrode showcasing exceptional acid-alkali resistance. The TiN nanomesh electrode, created by depositing a TiN coating on a naturally cracked gel film substrate via a sputtering method, maintains a stable electrical performance through thousands of bending cycles. It exhibits outstanding chemical stability, resisting strong acid and alkali corrosion, which is a key hurdle for current electrodes when in contact with acidic/alkaline materials and solvents during device fabrication. This, coupled with superior light transmission and conductivity (88% at 550 nm with a sheet resistance of ∼200 Ω/sq), challenges the reliance on conventional materials. Our TiN nanomesh electrode, successfully applied in electric heaters and electrically controlled thermochromic devices, offers broad potential beyond harsh environment applications. It enables alternative possibilities for the design and fabrication of future optoelectronics for advancements in this pivotal field.

Flexible Copper Nanowire/Polyvinylidene Fluoride Membranous Composites with a Frequency-Independent Negative Permittivity

With the increasing popularity of wearable devices, flexible electronics with a negative permittivity property have been widely applied to wearable devices, sensors, and energy storage. In particular, a low-frequency dispersion negative permittivity in a wide frequency range can effectively contribute to the stable working performance of devices. In this work, polyvinylidene fluoride (PVDF) was selected as the flexible matrix, and copper nanowires (CuNWs) were used as the conductive functional filler to prepare a flexible CuNWs/PVDF composite film with a low-frequency dispersion negative permittivity. As the content of CuNWs increased, the conductivity of the resulting composites increased sharply and presented a metal-like behavior. Moreover, the negative permittivity consistent with the Drude model was observed when CuNWs formed a percolative network. Meanwhile, the negative permittivity exhibited a low-frequency dispersion in the whole test frequency range, and the fluctuation of the permittivity spectra was relatively small (-760 to -584) at 20 kHz-1 MHz. The results revealed that the high electron mobility of CuNWs is reasonable for the low-frequency dispersion of negative permittivity. CuNWs/PVDF composite films with a frequency-independent negative permittivity provide a new idea for the development of flexible wearable electronic devices.

Synthesis of copper-reduced graphene oxide nanomaterials using glucose and study of its antibacterial and anticancer activities

In this work, glucose-capped copper nanoparticles decorated reduced graphene oxide nanomaterial are synthesized at 100 °C and 200 °C via chemical reduction method and studied for their antibacterial and anticancer activities. Synthesized nanomaterials were characterized using x-ray diffraction, Fourier-transform infrared, transmission electron microscope, and RAMAN. It is observed in transmission electron microscopy and selected area electron diffraction studies that copper nanoparticles deposited onto reduced graphene oxide are smaller than nanoparticles generated in the absence of reduced graphene oxide. Also, the size of copper nanoparticles synthesized at 200 °C is smaller than at 100 °C. Results suggest that Cu/Glu/rGO synthesized at both temperatures showed significant antibacterial activity againstEscherichia coliandBacillus anthracis,similarly, showed significant cell death in cancer cell lines [Cal33 and HCT-116 p53 (+/+)]. Interestingly, the nanomaterials were seen to be more effective against the cancer cell lines harboring aggregating mutant p53. Tumors with aggregating mutants of p53 are difficult to treat hence, Cu/Glu/rGO can be promising therapeutic agents against these difficult cancers. However, the antibacterial and anticancer activity of Cu/Glu/rGO synthesized at 100 °C where Cu2O form is obtained was found to be more effective compared to Cu/Glu/rGO synthesized at 200 °C where Cu form is obtained. Though fine-tuning of the material may be required for its commercial applications.

Copper nanoparticles embedded fungal chitosan as a rational and sustainable bionanozyme with robust laccase activity for catalytic oxidation of phenolic pollutants

Despite their potential for oxidation of persistent environmental pollutants, the development of rational and sustainable laccase nanozymes with efficient catalytic performance remains a challenge. Herein, fungal-produced chitosan-copper (CsCu) is proposed as a rational and sustainable bionanozyme with intrinsic laccase activity. The CsCu nanozyme was prepared by in situ reduction of copper on chitosan extracted from Irpex sp. isolate AWK2 a native fungus, from traditional fermented foods, yielding a low molecular weight chitosan with a 70% degree of deacetylation. Characterizations of the nanozyme using SEM-EDX, XRD, and XPS confirmed the presence of a multi-oxidation state copper on the chitosan matrix which is consistent with the composition of natural laccase. The laccase memetic activity was investigated using 2,4-DP as a substrate which oxidized to form a reddish-pink color with 4-AP (λmax = 510 nm). The CsCu nanozyme showed 38% higher laccase activity than the pristine Cu NPs at pH 9, indicating enhanced activity in the presence of chitosan structure. Further, CsCu showed significant stability in harsh conditions and exhibited a lower Km (0.26 mM) which is competitive with that reported for natural laccase. Notably, the nanozyme converted 92% of different phenolic substrates in 5 h, signifying a robust performance for environmental remediation purposes.

Room Temperature Curable Copper Nanowire-Based Transparent Heater

Copper nanowires (Cu NWs) are a promising alternative to silver NWs to develop transparent conducting films (TCFs) due to their comparable electrical conductivity and relative abundance. Postsynthetic modifications of the ink and high-temperature postannealing processes for obtaining conducting films are significant challenges that need to be addressed before commercial deployment of these materials. In this work, we have developed an annealing-free (room temperature curable) TCF with Cu NW ink that requires minimal postsynthetic modifications. Organic acid pretreated Cu NW ink is used for spin-coating to obtain a TCF with a sheet resistance of 9.4 Ω/sq. and optical transparency of 67.4% at 550 nm. For oxidation protection, the Cu NW TCF is encapsulated with polydimethylsiloxane (PDMS). The encapsulated film is tested as a transparent heater at various voltages and shows good repeatability. These results demonstrate the potential of Cu NW-based TCFs as a replacement for Ag-NW based TCFs for a variety of optoelectronic applications, such as transparent heaters, touch screens, and photovoltaics.

Enhancing the oxygen reduction activity by constructing nanocluster-scaled Fe2O3/Cu interfaces

Interface engineering is a promising strategy to enhance the catalytic performance of electrocatalysts for the oxygen reduction reaction (ORR). However, it is still a challenge to modulate the size into a suitable range (e.g., nanocluster-scale) to make the most of the interface. Moreover, the explicit mechanism of the interface for enhancing catalytic performance is still elusive. Herein, a model catalyst (FeCu@NC) loaded with nanocluster-scaled Fe₂O₃/Cu interfaces was prepared by modulating the metal components of the precursor to explore the enhancement of interface engineering for the ORR. Benefiting from the synergistic effect of the strong interfacial coupling effects of Fe₂O₃/Cu and optimized microstructure, FeCu@NC exhibited superior ORR activity and zinc-air battery performance. Experimental and theoretical calculations revealed that the presence of the Fe₂O₃/Cu interface breaks the traditional cognition to endow the Cu atoms (intrinsically inferior for the ORR) with a slight positive charge, which serves as the active sites for the ORR. This study provides a novel insight into the design of advanced electrocatalysts for the ORR by interface engineering.

Design and characterization of an urea-bridged PMO supporting Cu(II) nanoparticles as highly efficient heterogeneous catalyst for synthesis of tetrazole derivatives

In this work, a new periodic mesoporous organosilica with urea-bridges produced by the reaction of (3-aminopropyl)triethoxysilane and toluene-2,4-diisocyanate (APS-TDU-PMO) is introduced. The obtained APS-TDU-PMO was found to be an appropriate support for loading of Cu(II) nanoparticles to afford supramolecular Cu@APS-TDU-PMO nanocomposite. Uniformity and mesoporosity of both synthesized nanomaterials including APS-TDU-PMO and Cu@APS-TDU-PMO were proved by different spectroscopic, microscopic or analytical techniques including FTIR, EDX, XRD, FESEM, TEM, BET, TGA and DTA. Furthermore, the prepared Cu@APS-TDU-PMO nanomaterial was also used, as a heterogeneous and recyclable catalyst, for the synthesis of tetrazole derivatives through cascade condensation, concerted cycloaddition and tautomerization reactions. Indeed, the main advantages of this Cu@APS-TDU-PMO is its simple preparation and high catalytic activity as well as proper surface area which enable it to work under solvent-free conditions. Also, the introduced Cu@APS-TDU-PMO heterogeneous catalyst showed good stability and reusability for six consecutive runs to address more green chemistry principles.

Optimization of Au:CuO Thin Films by Plasma Surface Modification for High-Resolution LSPR Gas Sensing at Room Temperature

In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on the surface properties of the plasmonic thin films was studied, envisaging its optimization as gas sensors. Thus, this work pretends to attain the maximum sensing response of the thin film system and to demonstrate its potential as a gas sensor. The results show that as Ar plasma treatment time increases, the host CuO matrix is etched while Au nanoparticles are uncovered, which leads to an enhancement of the sensitivity until a certain limit. Above such a time limit for plasma treatment, the CuO bonds are broken, and oxygen is removed from the film's surface, resulting in a decrease in the gas sensing capabilities. Hence, the importance of the host matrix for the design of the LSPR sensor is also demonstrated. CuO not only provides stability and protection to the Au NPs but also promotes interactions between the thin film's surface and the tested gases, thereby improving the nanocomposite film's sensitivity. The optimized sensor sensitivity was estimated at 849 nm/RIU, which demonstrates that the Au-CuO thin films have the potential to be used as an LSPR platform for gas sensors.

Electrochemical valorization of waste activated sludge for short-chain fatty acids production

A tremendous amount of waste activated sludge (WAS) ends up in landfilling even after a substantial retention time during anaerobic digestion. This leftover activated sludge is an organic-rich material with the high potential to produce value-added chemicals such as short chain fatty acids (SCFAs). In the present study, a novel electrochemical conversion of activated sludge (E-WAS) was carried out on the surface of non-precious electrodes (nickel, stainless-steel and copper) in alkaline media at low applied potential and temperature. Cyclic voltammetry showed that Cu (II)/Cu (III) and Ni (II)/Ni(III) redox couple catalyzed the WAS oxidation reaction to produce SCFAs and hydrogen. The results revealed that Cu(II)/Cu(III) has higher catalytic oxidation capability towards SCFAs. Yields of 48.7, 21.4, and 14.6 mg SCFAs per g of volatile solids were achieved by using copper, nickel and stainless-steel as working electrodes, respectively. Post analysis characterization techniques indicate that copper oxide films lead to WAS oxidation. Total volatile solid removal of 30% was obtained at 35°C and 1.65 V in 0.2 M NaOH after 2 h of operation in an electrochemical digestor with copper electrodes which is more efficient than a conventional alkaline treatment (24 h, 55%, 1M NaOH). Ammonia was produced as the by-product of E-WAS oxidation. The highest amount of ammonia (250 mg L−1) was obtained by using nickel as the working electrode after 2 h operation at 35°C and 1.35 V applied potential. The change in WAS morphology revealed that the copper oxide film is an effective electrocatalyst for WAS disinfection.

Influence of the Microstructure and Optical Constants on Plasmonic Properties of Copper Nanolayers

Copper layers with thicknesses of 12, 25, and 35 nm were thermally evaporated on silicon substrates (Si(100)) with two different deposition rates 0.5 and 5.0 Å/s. The microstructure of produced coatings was studied using atomic force microscopy (AFM) and powder X-ray diffractometer (XRD). Ellipsometric measurements were used to determine the effective dielectric functions <ε˜> as well as the quality indicators of the localized surface plasmon (LSP) and the surface plasmon polariton (SPP). The composition and purity of the produced films were analysed using X-ray photoelectron spectroscopy (XPS).

SiN x /Cu Spectral Beam Splitting Films for Hybrid Photovoltaic and Concentrating Solar Thermal Systems

Spectral beam splitting (SBS) films are crucial for the development of hybrid systems based on photovoltaic (PV) and concentrating solar thermal (CST) technologies. In this study, a novel double-layer SiN _x /Cu SBS film was prepared via magnetron sputtering. This film was developed based on the linear Fresnel solar thermal technology used in PV/CST hybrid systems. The as-deposited film exhibited superior SBS properties, with a high transmittance of 72.9% and a reflectance of 89.7%. To optimize the optical properties, the thicknesses of the metal and SiN _x layers were precisely controlled. The optimal thicknesses of the Cu and SiN _x layers were determined to be 17 and 67 nm, respectively. Furthermore, the thermal stability of the SBS film was evaluated. When annealed at 50 °C, the surface of the SBS film became more uniform and smooth, and with increasing annealing time, the film became denser. No strong diffraction peaks of Cu were observed in the X-ray diffraction patterns because of the low content and poor crystallization of Cu. Atomic force microscopy investigations revealed the formation of a textured surface and a decrease in the root-mean-square roughness with an increase in the annealing time from 0 to 360 h. As a key component with considerable application potential in PV/CST hybrid systems, SBS films are currently an important research topic.

Development of Multi-concentration Cu:Ag Bimetallic Nanoparticles as a Promising Bactericidal for Antibiotic-Resistant Bacteria as Evaluated with Molecular Docking Study

The present study is concerned with evaluating the influence of various concentrations of Ag within Cu:Ag bimetallic nanoparticles developed for use as a promising anti-bacterial agent against antibiotic-resistant bacteria. Here, Cu:Ag bimetallic nanoparticles with various concentration ratios (2.5, 5.0, 7.5, and 10 wt%) of Ag in fixed amount of Cu labeled as 1:0.025, 1:0.050, 1:0.075, and 1:0.1 were synthesized using co-precipitation method with ammonium hydroxide and deionized water as solvent, polyvinyl pyrrolidone as a capping agent, and sodium borohydride and ascorbic acid as reducing agents. These formulated products were characterized through a variety of techniques. XRD confirmed phase purity and detected the presence of distinct fcc structures belonging to Cu and Ag phases. FTIR spectroscopy confirmed the presence of vibrational modes corresponding to various functional groups and recorded characteristic peak emanating from the bimetallic. UV-visible spectroscopy revealed reduction in band gap with increasing Ag content. SEM and HR-TEM micrographs revealed spherical morphology of Ag-doped Cu bimetallic with small and large scale agglomerations. The samples exhibited varying dimensions and interlayer spacing. Bactericidal action of synthesized Cu:Ag bimetallic NPs depicted statistically significant (P < 0.05) inhibition zones recorded for various concentrations of Ag dopant against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Acinetobacter baumannii (A. baumannii) ranging from (0.85-2.8 mm), (0.55-1.95 mm) and (0.65-1.85 mm), respectively. Broadly, Cu:Ag bimetallic NPs were found to be more potent against gram-positive compared with gram-negative. Molecular docking study of Ag-Cu bimetallic NPs was performed against β-lactamase which is a key enzyme of cell wall biosynthetic pathway from both S. aureus (Binding score: - 4.981 kcal/mol) and A. bauminnii (Binding score: - 4.013 kcal/mol). Similarly, binding interaction analysis against FabI belonging to fatty acid biosynthetic pathway from A. bauminnii (Binding score: - 3.385 kcal/mol) and S. aureus (Binding score: - 3.012 kcal/mol) along with FabH from E. coli (Binding score: - 4.372 kcal/mol) was undertaken. These theoretical computations indicate Cu-Ag bimetallic NPs as possible inhibitor of selected enzymes. It is suggested that exploring in vitro inhibition potential of these materials may open new avenues for antibiotic discovery.

EMI Shielding of the Hydrophobic, Flexible, Lightweight Carbonless Nano-Plate Composites

The cost-effective spray coated composite was successfully synthesis and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction techniques. The one step synthetic strategy was used for the synthesis of nanoplates that have a crystalline nature. The composites are amorphous and hydrophobic with micron thickness (<400 m). The maximum contact angle showed by composite is 132.65° and have wetting energy of -49.32 mN m-1, spreading coefficient -122.12 mN m-1, and work of adhesion 23.48 mN m-1. The minimum thickness of synthesized nanoplate is 3 nm while the maximum sheet resistance, resistivity, and electrical conductivity of the composites are 11.890 ohm sq-1, 0.4399 Ω.cm-1, and 8.967 S.cm-1, respectively. The cobalt nanoplate coated non-woven carbon fabric (CoFC) possesses excellent sheet resistance, hydrophobic nature, and EMI shielding efficiency of 99.99964%. The composite can block above 99.9913% of incident radiation (X band). Hence, the composite can be utilized in application areas such as medical clothes, mobile phones, automobiles, aerospace, and military equipment.

Synchronously improved reliability, figure of merit and adhesion of flexible copper nanowire networks by chitosan transition

Copper nanowires (CuNWs) are remarkable components that can replace indium tin oxide as transparent electrodes due to their low cost, high conductivity and acceptable transmittance. However, a common coating method can cause poor electrical, optical and adhesive properties because of the creation of loosely connected junctions. In addition, the unsatisfactory thermal and environmental stabilities limit the practical applications. These problems should be overcome in CuNW-based films for reliable transparent electrodes through material and engineering approaches. In this work, a novel transparent composite electrode composed of chitosan and CuNWs on a flexible polyethylene terephthalate (PET) substrate, with synchronously strengthened adhesion, as well as heightened transmittance, reduced resistivity, improved flexibility, enhanced thermal stability and increased environmental stability, was prepared without vacuum processing and high-temperature annealing. The effects of the number of CuNW network layers and chitosan concentration on the performance of chitosan/CuNW composite transparent electrodes were studied. The resulting electrodes exhibitan excellent conductivity (sheet resistance: 15.6 Ω sq^-1) and a superior optical transmittance (∼87%) at 550 nm. Calculation of the figure of merit displays a high value of 168, which is the highest among all the reported CuNW-based transparent electrodes. Meanwhile, the sheet resistance did not show great change after 10 tape tests and 10 000 bending cycles, suggesting good adhesion to the PET substrate and outstanding mechanical flexibility. Moreover, the composite transparent electrodes show good stability to resist long-term storage and temperature variation in thermal environment.

Process Parameters for FFF 3D-Printed Conductors for Applications in Sensors

With recent developments in additive manufacturing (AM), new possibilities for fabricating smart structures have emerged. Recently, single-process fused-filament fabrication (FFF) sensors for dynamic mechanical quantities have been presented. Sensors measuring dynamic mechanical quantities, like strain, force, and acceleration, typically require conductive filaments with a relatively high electrical resistivity. For fully embedded sensors in single-process FFF dynamic structures, the connecting electrical wires also need to be printed. In contrast to the sensors, the connecting electrical wires have to have a relatively low resistivity, which is limited by the availability of highly conductive FFF materials and FFF process conditions. This study looks at the Electrifi filament for applications in printed electrical conductors. The effect of the printing-process parameters on the electrical performance is thoroughly investigated (six parameters, >40 parameter values, >200 conductive samples) to find the highest conductivity of the printed conductors. In addition, conductor embedding and post-printing heating of the conductive material are researched. The experimental results helped us to understand the mechanisms of the conductive network’s formation and its degradation. With the insight gained, the optimal printing strategy resulted in a resistivity that was approx. 40% lower than the nominal value of the filament. With a new insight into the electrical behavior of the conductive material, process optimizations and new design strategies can be implemented for the single-process FFF of functional smart structures.

Highly Electroconductive Nanopapers Based on Nanocellulose and Copper Nanowires: A New Generation of Flexible and Sustainable Electrical Materials

Nowadays, the development of sustainable high-performance functional nanomaterials is in the spotlight. In this work, we report the preparation of a new generation of flexible and high electroconductive nanopapers based on nanofibrillated cellulose (NFC) and copper nanowires (CuNWs). Homogeneous red brick color nanopapers (thickness 30.2-36.4 μm) were obtained by mixing different amounts of NFC aqueous suspensions and CuNWs (1, 5, 10, 20, and 50 wt %), followed by vacuum filtration and drying. scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the incorporation of the different amounts of CuNWs, and their uniform and random distribution. All of the nanomaterials displayed good mechanical properties, viz., Young's modulus = 2.62-4.72 GPa, tensile strength = 30.2-70.6 MPa, and elongation at break = 2.3-4.1% for the nanopapers with 50 and 1 wt % of CuNWs mass fraction, respectively. The electrical conductivity of these materials strongly depends on the CuNW content, attaining a value of 5.43 × 10⁴ S·m^-1 for the nanopaper with a higher mass fraction. This is one of the highest values reported so far for nanocellulose-based conductive materials. Therefore, these nanopapers can be seen as an excellent inexpensive and green alternative to the current electroconductive materials for applications in electronic devices, energy storage, or sensors.

Aptamer-Functionalized Three-Dimensional Carbon Nanowebs for Ultrasensitive and Free-Standing PDGF Biosensor

Research on flexible biosensors is mostly focused on their use in obtaining information on physical signals (such as temperature, heart rate, pH, and intraocular pressure). Consequently, there are hardly any studies on using flexible electronics for detecting biomolecules and biomarkers that cause diseases. In this study, we propose a flexible, three-dimensional carbon nanoweb (3DCNW)-based aptamer sensor to detect the platelet-induced growth factor (PDGF), which is an oncogenic biomarker. As a template for the 3D structure, poly(acrylonitrile) (PAN) nanowebs were synthesized using a facile electrospinning process. The PAN nanowebs were then subjected to chemical vapor deposition with copper powder. This was followed by Cu etching to generate carbon protrusions on the web surface. As an active site, PDGF-B binding aptamer was introduced on the 3DCNW surface to form biosensor electrodes. The 3DCNW-based aptasensor exhibited excellent sensitivity (down to 1.78 fM), with high selectivity, reversibility, and stability to PDGF-BB.

A Novel Preparation of Nano-Copper Chalcogenide (Cu2S)-based Flexible Counter Electrode

Copper nanowires (CuNWs) are used to prepare flexible, transparent conducting substrates due to their low cost and ease of fabrication on a large area. A CuNW/polymer composite substrate was prepared and vulcanized to create a novel flexible nano-Cu₂S/polymer composite substrate. The physical and photovoltaic properties of the substrate can be controlled by tuning the concentration of CuNW dispersion during the preparation of CuNWs and nano Cu₂S films. The nano-Cu₂S-based composite substrate was used as an effective flexible counter electrode of a quantum-dot-sensitized solar cell (QDSSC) and resulted in a maximum cell efficiency of 1.01%.

Ag fiber/IZO Composite Electrodes: Improved Chemical and Thermal Stability and Uniform Light Emission in Flexible Organic Light-Emitting Diodes

Electrospun metal fiber is a promising flexible transparent electrode owing to its extremely long length and facile fabrication process. However, metal-fiber electrodes have problems with chemical and thermal stability and nonuniform emission in organic light-emitting diode (OLED) at low luminance. In this study, we proposed a Ag fiber/IZO composite electrode with high stability. Ag fiber/IZO composite electrodes exhibited chemical and thermal stability. In addition, it was demonstrated that the OLED with the Ag fiber/IZO composite electrode operated stably, and the uniform emission of the OLED with metal-fiber electrodes improved by using highly conductive IZO film.