Search Results (112)

In recent years, organic dye contamination has posed a significant threat to water safety. This study presents a novel composite photocatalyst comprising graphitic carbon nitride quantum dots (g-C3N4QDs) supported on a copper-based metal–organic framework (Cu-MOF) for efficient visible-light degradation of organic pollutants. The g-C₃N₄QDs were synthesized via a facile strategy and subsequently immobilized onto the Cu-MOF support. Comprehensive characterization including SEM, TEM, XRD, BET, UV-Vis DRS, PL, and EIS confirmed the successful formation of a heterostructure, revealing that an optimized loading of g-C₃N₄QDs significantly enhanced light absorption, facilitated charge separation, and increased the specific surface area, with the optimal composite exhibiting 273 m²/g compared to 112 m²/g for the pristine Cu-MOF. Electrochemical analyses indicated a 2.38-fold enhancement in photocurrent density and a reduced interfacial charge transfer resistance, reflecting superior electron–hole pair separation. Crucially, the optimized g-C₃N₄QDs/Cu-MOF composite demonstrated exceptional photocatalytic performance, achieving 96.6% degradation of Congo red (100 mg/L) within 30 min under visible light irradiation, substantially outperforming the 77.6% degradation attained by the pristine Cu-MOF. This enhancement is attributed to the synergistic effects of improved light harvesting, efficient interfacial charge transfer across the heterojunction, and an enlarged active surface area. The composite exhibits considerable potential as a high-performance and stable photocatalyst for purifying dye-contaminated wastewater. Full article

Tantalum nitride (TaN) coatings are valued for their hardness, chemical inertness, and biocompatibility; however, they lack intrinsic antibacterial properties, which limits their application in biomedical environments. Introducing copper (Cu) into the TaN matrix offers a potential solution by combining TaN’s mechanical and chemical durability with Cu’s well-documented antimicrobial action. This study explores how varying copper incorporation affects the structural, electrical, photocatalytic, and antibacterial characteristics of TaCuN multilayer films synthesized via reactive magnetron sputtering. Three thin TaCuN films were fabricated using a high-power reactive magnetron co-sputtering system, varying the Cu target power to control the composition. Structural and morphological analysis was performed using X-ray diffraction (XRD), scanning/transmission electron microscopy (STEM/TEM), and energy-dispersive X-ray spectroscopy (EDS). Electrical conductivity was studied along and across the film surfaces at temperatures ranging from 20 to 375 K using AC impedance spectroscopy. Optical and photocatalytic properties were assessed using UV–Vis spectroscopy and methylene blue degradation tests. Antibacterial activity against Staphylococcus aureus was analyzed under visible light using CFU reduction tests. XRD and TEM analyses revealed a multilayered four-zone architecture with alternating Ta-, Cu-, and N-rich phases and a dominant cubic δ-TaN pattern. The layers exhibited pronounced conductivity anisotropy, with in-plane conductivity (~10³ Ω⁻¹ cm⁻¹) exceeding cross-plane conductivity by ~10⁷ times, attributed to the formation of a metallic conduction channel in the mid-layer. Optical spectra indicated limited light absorption above 300 nm and negligible photocatalytic activity. Increasing the Cu content substantially enhanced antibacterial efficiency, with the highest-Cu sample achieving 95.6 % bacterial growth reduction. Morphological evaluation indicated that smooth film surfaces (Ra < 0.2 μm) effectively minimized bacterial adhesion. Reactive magnetron sputtering enables the precise engineering of TaCuN multilayers, combining high electrical anisotropy with robust antibacterial functionality. The optimized TaCuN coating offers promising potential in biomedical and protective applications where both conductivity and microbial resistance are required. Full article

It is well known that nitrite is widely used in industrial and agricultural sectors as a preservative, corrosion inhibitor, and intermediate in chemical synthesis; consequently, nitrite residues are often present in food, water, and the environment as a result of meat curing, fertilizer use, and wastewater discharge. Despite having several applications, nitrite exerts toxic effects on human beings and aquatic life. Therefore, the monitoring of nitrite is of particular significance to avoid negative impacts on human health, the environment, and aquatic life. Previously, the electrochemical method has been extensively used for the development of nitrite sensors using various advanced electrode materials. Additionally, zinc oxide (ZnO), cerium oxide (CeO₂), titanium dioxide (TiO₂), copper oxide (CuO), iron oxides, nickel oxide (NiO), polymers, MXenes, reduced graphene oxide (rGO), carbon nanotubes (CNTs), graphitic carbon nitride (gCN), metal–organic frameworks (MOFs), and other composites have been utilized as electrocatalysts for the fabrication of nitrite electrochemical sensors. This review article provides an overview of the construction of nitrite sensors using advanced electrode materials. The electrochemical activities of the reported nitrite sensors are discussed. Furthermore, limitations and future perspectives regarding the determination of nitrite are discussed. Full article

Copper (Cu) is widely used in electrical, electronic, and tribological systems owing to its excellent electrical and thermal conductivity. However, its relatively low hardness and poor wear resistance limit its use in demanding engineering applications. In this study, Cu-based hybrid metal matrix composites (MMCs) reinforced with hexagonal boron nitride (h-BN) and boron carbide (B₄C) were fabricated via spark plasma sintering (SPS) to improve their mechanical and tribological performance. The h-BN content was fixed at 1 wt.% to ensure solid lubrication, while the B₄C content was varied (0.25, 0.5, 0.75, and 1 wt.%) to examine its influence on the microstructural, mechanical, electrical, and wear properties of the composites. Microstructural analyses confirmed a homogeneous distribution of h-BN and B₄C particles in the Cu matrix at low and moderate reinforcement levels, whereas excessive B₄C resulted in partial agglomeration and reduced densification. All composites achieved relative densities above 95%, demonstrating the high densification efficiency of the SPS process. Hardness increased markedly with B₄C addition due to dispersion strengthening and grain refinement, while electrical conductivity decreased slightly because of the insulating nature of the reinforcements. Tribological tests showed that the composite containing 0.75 wt.% B₄C exhibited the best performance, with the lowest wear rate and stable friction behavior. Overall, the results indicate that co-reinforcing Cu with h-BN and B₄C through SPS is a promising strategy for developing multifunctional materials suitable for electrical contact and sliding applications. Full article

Background/Objectives: A comparative study of silver (Ag), titanium nitride (TiN), zirconium nitride (ZrN), and copper (Cu) coatings on titanium (Ti) disks, considering the specifications of a microporous skin- and bone-integrated titanium pylon (SBIP), was performed to assess their biocompatibility, osseointegration, and mechanical properties. Methods: To assess cytotoxicity and biocompatibility, Ti disks with various metal coatings were co-cultured with FetMSCs and MG-63 cells for 1, 3, 7, and 14 days and subsequently evaluated using a cell viability assay, as supported by SEM and confocal microscopy studies. The antimicrobial activity of the selected four materials coating the implants was tested against S. aureus by mounting Ti disks onto the surface of LB agar dishes spread with a bacterial suspension and measuring the diameter of the growth inhibition zones. Quantitative Real-Time Polymerase Chain Reaction (RT-PCR) analysis of the relative gene expression of biomarkers that are associated with extracellular matrix components (fibronectin, vitronectin, type I collagen) and cell adhesion (α2, α5, αV integrins), as well as of osteogenic markers (osteopontin, osteonectin, TGF-β1, SMAD), was performed during the 14-day follow-up period. Additionally, the activity of matrix metalloproteinases (MMP-1, -2, -8, -9) was assessed. Results: All samples with metal coatings, except the copper coating, demonstrated a good cytotoxicity profile, as evidenced by the presence of a cellular monolayer on the sample surface on the 14th day of the follow-up period (as shown by SEM and inverted confocal microscopy). All metal coatings enhanced MMP activity, as well as cellular adhesion and osteogenic marker expression; however, TiN showed the highest values of these parameters. Significant inhibition of bacterial growth was observed only in the Ag-coated Ti disks, and it persisted for over 35 days. Conclusions: The silver-based coating, due to its high antibacterial activity, low cytotoxicity, and biointegrative capacity, can be recommended as the coating of choice for microporous titanium implants for further preclinical studies. Full article

Copper nitride (Cu₃N) is gaining attention as an eco-friendly thin-film semiconductor in a myriad of applications, including storage devices, microelectronic components, photodetectors, and photovoltaic cells. This work presents a detailed optoelectronic study of Cu₃N thin films grown by reactive RF-magnetron sputtering under pure N₂. An overview of the state-of-the-art literature on this material and its potential applications is also provided. The studied films consist of Cu₃N polycrystals with a cubic anti-ReO₃ type structure exhibiting a preferential (100) orientation. Their optical properties across the UV-Vis-NIR spectral range were investigated using a combination of multi-angle spectroscopic ellipsometry, broadband transmission, and reflection measurements. Our model employs a stratified geometrical approach, primarily to capture the depth-dependent compositional variations of the Cu₃N film while also accounting for surface roughness and the underlying glass substrate. The complex dielectric function of the film material is precisely determined through an advanced dispersion model that combines multiple oscillators. By integrating the Tauc–Lorentz, Gaussian, and Drude models, this approach captures the distinct electronic transitions of this polycrystal. This customized optical model allowed us to accurate extract both the indirect (1.83–1.85 eV) and direct (2.38–2.39 eV) bandgaps. Our multifaceted characterization provides one of the most extensive studies of Cu₃N thin films to date, paving the way for optimized device applications and broader utilization of this promising binary semiconductor, and showing its particular potential for photovoltaic given its adequate bandgap energies for solar applications. Full article

This study addresses challenges in recycling electronic waste (e-waste) by developing a self-degrading electrical wire coating material using graphitic carbon nitride (g-C₃N₄). Two types, melamine-derived carbon nitride (MCN) and urea-derived carbon nitride (UCN), were synthesized and evaluated for their photocatalytic activity by measuring the decolorization rate of rhodamine-B (RhB). UCN demonstrated superior photocatalytic performance compared to the widely used TiO₂. When incorporated into PVC film, UCN achieved a maximum weight loss of 68% in photodegradation tests after 40 days of irradiation, contributing to reduced environmental impact. A UCN-mixed coating for a vinyl-insulated cable prototype showed that photodecomposition in water facilitated copper wire separation. The study also indicated that water is vital for the decomposition process, while UCN enhanced stiffness and tensile strength of the material without compromising elongation and electrical insulation properties. Full article

Graphitic carbon nitride is recognized as a very promising support structure to anchor single atoms and small, sub-nanometric metal clusters, with vast applications in catalysis. In the current manuscript, we aim to study the geometry and electronic structures of the small, sub-nanometric monometallic (copper or nickel) and bimetallic (copper–nickel) clusters anchored to the graphitic carbon nitride. Our Density Functional Theory (DFT) study reveals that Cu and Ni, when in the form of isolated single atoms, lie in the plane of the support. Once the atoms agglomerate and form small clusters, they tend to bind above the carbon nitride (C₃N₄) plane. The nickel atoms form shorter bonds with the support than the copper atoms do, which is reflected by the binding energies. Atoms directly bound to the support become oxidized, forming electrophilic sites at the surface. The computed negative metal–support binding energies mean that the investigated Cu/Ni-C₃N₄ composites are stable, and the metal species will not easily leach from the support. Full article

As power electronic modules are increasingly required to provide improved heat dissipation, aluminum nitride (AlN) stands out against other ceramic materials. At the same time, more cost-efficient production of customized products demands shorter development cycles and innovative manufacturing processes. Conventional process chains in power electronics are usually long and inflexible; thus, innovative ways to reduce process steps and faster prototyping are needed. Therefore, this study investigates the usage of additive manufacturing technology—laser-based powder bed fusion of metal powder (PBF-LB/M)—namely copper (Cu), on AlN substrates for power electronic applications. It is found that specific electrical conductivity values can be achieved up to 31 MS/m, and adhesion measured by shear testing reaches 15 MPa. In reliability testing, the newly produced samples exhibit a 25% decrease in adhesion after 250 cycles, which is comparatively moderate. This study shows the feasibility of PBF-LB/M of Cu powder on AlN, emphasizing its strengths and highlighting remaining weaknesses. Full article

Thermal management reveals an increasing importance due to the changing demands in terms of the compactness and the performance of electronic devise. Polymers in general and thermosets specifically depict a low thermal conductivity, where filler systems are needed to improve performance and make polymers suitable for certain applications. So far, different influencing factors in terms of improving the thermal conductivity in thermosets, mainly through the use of single-filler systems, have been investigated in. To some extent, hybrid filler systems have been examined as well; however, the behavior itself in terms of the thermal conductivity as well as the mechanical properties is rather unknown. In terms of the applications, it is essential to understand the correlation between the thermal conductivity and the mechanical properties as this is the fundamental requirement to realize a proper dimensioning of samples in applications. Therefore, this paper investigates hybrid filler systems based on boron nitride (BN) and three different second fillers with varying ratios and in terms of both the improvement of the thermal conductivity and the mechanical properties. Copper (Cu) was shown to reach the best compromise within the hybrid materials. Furthermore, criteria of an improved thermal flow path and sufficient mechanical properties have been stated in general. Full article

The rapid growth in population and industrialization have significantly increased global energy demand, placing immense pressure on finite and environmentally harmful conventional fossil fuel-based energy sources. In this context, the development of hybrid electrocatalysts presents a crucial solution for energy conversion and storage, addressing environmental challenges while meeting rising energy needs. In this study, the fabrication of a novel bifunctional catalyst, copper nickel aluminum spinel (Cu_0.5Ni_0.5Al₂O₄) supported on graphitic carbon nitride (GCN), using a solid-state synthesis process is reported. Because of its effective interface design and spinel cubic structure, the Cu_0.5Ni_0.5Al₂O₄/GCN nanocomposite, as synthesized, performs exceptionally well in electrochemical energy conversion, such as the oxygen evolution reaction (OER), the hydrogen evolution reaction (HER), and energy storage. In particular, compared to noble metals, Pt/C- and IrO₂-based water-splitting cells require higher voltages (1.70 V), while for the Cu_0.5Ni_0.5Al₂O₄/GCN nanocomposite, a voltage of 1.49 V is sufficient to generate a current density of 10 mA cm⁻² in an alkaline solution. When used as supercapacitor electrode materials, Cu_0.5Ni_0.5Al₂O₄/GCN nanocomposites show a specific capacitance of 1290 F g⁻¹ at a current density of 1 A g⁻¹ and maintain a specific capacitance of 609 F g⁻¹ even at a higher current density of 5 A g⁻¹, suggesting exceptional rate performance and charge storage capacity. The electrode’s exceptional capacitive properties were further confirmed through the determination of the roughness factor (Rf), which represents surface heterogeneity and active area enhancement, with a value of 345.5. These distinctive characteristics render the Cu_0.5Ni_0.5Al₂O₄/GCN composite a compelling alternative to fossil fuels in the ongoing quest for a viable replacement. Undoubtedly, the creation of the Cu_0.5Ni_0.5Al₂O₄/GCN composite represents a significant breakthrough in addressing the energy crisis and environmental concerns. Owing to its unique composition and electrocatalytic characteristics, it is considered a feasible choice in the pursuit of ecologically sustainable alternatives to fossil fuels. Full article

The demand for a “green” approach to the synthesis of nanomaterials is becoming increasingly pressing. In response to this need, we present, for the first time, the use of spark ablation as an environmentally friendly deposition technique to obtain nanoparticles of copper nitride, a material that is gaining increasing attention in the field of photovoltaic advanced technologies. This method involves the ablation of pure copper electrodes in nitrogen atmosphere while a spark current is tuned. The overall result is the co-presence of nitride and oxide nanoparticle agglomerates with different sizes according to the spark current, as confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive spectroscopy techniques. Scanning probe microscopy and scanning electron microscopy show an increase in the number and size of nanoparticle agglomerates with an increasing current, while the nanoparticle size is always about sub-10 nm. The findings of this work promote spark ablation as a simple, versatile, cost-effective, environmentally friendly deposition method to obtain nitride-based nanoparticles. Furthermore, it is compatible with many types of materials and substrates, increasing the possible combinations of metals/semiconductors and carrier gas types to obtain completely innovative materials with unique compositions and properties. Full article

The early and accurate detection of cancer remains a critical challenge in biomedical diagnostics. In this work, we propose and investigate a novel surface plasmon resonance (SPR) biosensor platform based on a multilayer configuration incorporating copper (Cu), silicon nitride (Si₃N₄), and molybdenum disulfide (MoS₂) for the optical detection of various cancer types. Four distinct sensor architectures (Sys₁–Sys₄) were optimized through the systematic tuning of Cu thickness, Si₃N₄ dielectric layer thickness, and the number of MoS₂ monolayers to enhance sensitivity, angular shift, and spectral sharpness. The optimized systems were evaluated using refractive index data corresponding to six cancer types (skin, cervical, blood, adrenal, breast T1, and breast T2), with performance metrics including sensitivity, detection accuracy, quality factor, figure of merit, limit of detection, and comprehensive sensitivity factor. Among the configurations, Sys₃ (BK7–Cu–Si₃N₄–MoS₂) demonstrated the highest sensitivity, reaching 254.64 °/RIU for adrenal cancer, while maintaining a low detection limit and competitive figures of merit. Comparative analysis revealed that the MoS₂-based designs, particularly Sys₃, outperform conventional noble-metal architectures in terms of sensitivity while using earth-abundant, scalable materials. These results confirm the potential of Cu/Si₃N₄/MoS₂-based SPR biosensors as practical and effective tools for label-free cancer diagnosis across multiple malignancy types. Full article

As a pioneering exploration of gallium nitride (GaN) as reinforcement in metal matrix composites, this study systematically investigated the mechanical–electrical property evolution in copper matrix composites through controlled GaN incorporation—a research gap scarcely addressed previously. GaN-Cu composites with tailored GaN contents were successfully synthesized by precisely controlled mechanical alloying and powder metallurgical processing and exhibited exceptional mechanical–electrical synergies. Advanced microstructural characterization via X-ray diffraction and electron microscopy revealed the homogeneous dispersion of GaN nanoparticles within the Cu matrix, forming coherent interfacial structures. The characterization results show that GaN-Cu composites could be successfully prepared by mechanical alloying and powder metallurgy methods, and it was confirmed that GaN nanoparticles could improve the mechanical properties of metal matrix composites as reinforcement; with an exponential increase in GaN content, the decrease in conductivity became very slow. With an increase in GaN content, the electrical conductivity decreased in an “L” shape, while the hardness first increased and then decreased, but the hardness could reach up to 128.66 HV, which is about 130% higher than that of the substrate. Full article

A comprehensive X-ray topography analysis of two selected aluminum nitride (AlN) bulk crystals is presented. We compare surface inspection X-ray topography in back-reflection geometry with high-energy transmission topography in the Lang and Laue configuration using the monochromatic K_α1 excitation wavelength of copper, silver, and tungsten, respectively. A detailed comparison of the results allows the assessment of both the high- and low-energy X-ray topography methods with respect to performance and structural information, giving essential feedback for crystal growth. This is demonstrated for two selected AlN freestanding faceted crystals up to 8 mm in thickness grown in all directions using the physical vapor transport (PVT) method. Structural defects of all facets of the crystals are determined using the X-ray topography in back-reflection geometry. The mean threading dislocation densities are 480 ± 30 cm⁻² for both crystals of either the Al- or N-face. Clustering of dislocations could be observed. The m-facets show the presence of basal plane dislocations and their accumulation as clusters. The integral transmission topographs of the $10\overline{1}0$ (m-plane) reflection family show that basal plane dislocations of the screw type in ${\displaystyle \frac{1}{3}}⟨\overline{1}2\overline{1}0⟩$ directions decorate threading dislocation clusters. Three-dimensional section transmission topography reveals that the basal plane dislocation clusters mainly originate at the seed boundary and propagate in the ${\displaystyle \frac{1}{3}}⟨\overline{1}2\overline{1}0⟩$ direction along the growth front. In newly laterally grown material, the Borrmann effect has been observed for the first time in PVT-grown bulk AlN, indicating very high structural perfection of the crystalline material in this region. This agrees with a low mean FWHM of 10.6 arcsec of the $10\overline{1}0$ reflection determined through focused high-energy Laue transmission mappings. The latter method also opens the analysis of the $∆2\theta$-shift correlated to the residual stress distribution inside the bulk crystal, which is dominated by dislocation clusters. Contrary to Lang transmission topography, the de-focused high-energy Laue transmission penetrates the 8 mm-thick crystal enabling a defect analysis in the bulk. Full article