Search Results (89)

CuO/TiO₂ is a highly active visible-light-driven photocatalyst. The precise structural regulation of TiO₂ and the quantum dot-scale loading strategy of CuO have long been researching hotspots and challenges. This work presents an ingenious synthetic strategy, leveraging the photoinduced superhydrophilicity and dark-induced reversible hydrophobicity of TiO₂, coupled with carbon quantum dots (CQDs) as “seeds” to induce the in situ synthesis of CuO quantum dots (CuO QDs). Specifically, CuO QDs with an average diameter of 5–10 nm were successfully anchored onto TiO₂ nanowire arrays (TNWAs) with a diameter of 10–15 nm. By adjusting the dosage of “seeds” (CQDs), the loading amount of CuO QDs can be effectively controlled. Corresponding characterizations were performed, including ultraviolet-visible-near-infrared (UV-Vis-NIR spectroscopy) for optical absorption properties, photoluminescence (PL) spectroscopy for photoluminescent behavior, electron paramagnetic resonance (EPR) spectroscopy for free radical generation capability, and bisphenol A (BPA) degradation assays for photocatalytic performance. Loading 4.78 wt% CuO QDs can effectively inhibit the recombination of electron–hole pairs in TNWAs. Simultaneously, it prolongs the lifetime of charge carriers (photoelectrons) and enhances the yields of hydroxyl radicals (•OH) and superoxide radicals (•O₂⁻). The BPA degradation efficiency of the CuO QDs/TNWA composite is 2.4 times higher than that of TNWAs. Furthermore, we found that the loading of CuO QDs significantly modulates the depletion layer width of the P–N heterojunction, and the underlying mechanism has been discussed in detail. Full article

Indium oxide-based gas sensors have been proven to be a promising material for detecting nitrogen dioxide (NO₂) gas because of its wide bandgap and stability. In this paper, the enhancement mechanism for the sensitivity of indium oxide NO₂ gas sensors was systematically investigated using density functional theory (DFT) calculations and experimental validation with noble metals like Au, Ag, Pt, Pd, and Cu. We have fabricated a GaN nanowire-based NO₂ gas sensor functionalized with In₂O₃ and decorated with noble metals using a standard fabrication technique. Experimental tests showed that Au/In₂O₃ sensors exhibited the highest response of 38.9% followed by bare In₂O₃ with 10% for 10 ppm NO₂ at room temperature. The sensing properties were mainly attributed to a spillover effect or catalytic performance of Au with In₂O₃. The adsorption energies, charge transfers, and band gap confirm the enhanced sensing capability of Au-decorated Indium oxide for a NO₂ gas sensor. Full article

Rapid on-site detection of chemical warfare agents (CWAs) is vital for security and environmental monitoring. In this work, copper(I) oxide (Cu₂O) nanowire (NW) chemiresistors were investigated as gas sensors for low-concentration organophosphorus chemical warfare agent (CWA) simulants. The NWs were hydrothermally synthesized and deposited onto microheater platforms, enabling them to operate at elevated working temperatures. Their sensing performance was tested against a range of vapor-phase simulants, including dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), diethyl ethylphosphonate (DEEP), diphenyl phosphoryl chloride (DPPCl), parathion, diethyl phosphite (DEP), diethyl adipate (DEA), and cyanogen chloride (ClCN). Fully oxidized P(V) simulants (DMMP, DEEP, TEP) produced modest, predominantly reversible responses (~3–6% RR). On the contrary, DPPCl and DEP induced the strongest relative responses (RR −94.67% and >200%, respectively), accompanied by irreversible surface modification as revealed by SEM and EDS. ClCN produced a substantial but reversible negative response (RR −9.5%), consistent with transient oxidative interactions. Surface poisoning was confirmed after exposure to DEP and DPPCl, which left phosphorus or chlorine residues on the Cu₂O surface. These results highlight both the promise and limitations of Cu₂O NW chemiresistors for selective CWA detection. Full article

This study reports the development of a highly sensitive electrochemical sensor for phosphate ion detection, utilizing silicon nanowires (SiNWs) as the transducing elements and a novel copper (II) phthalocyanine-acrylate polymer adduct (Cu (II) Pc-PAA) as the functional sensing layer. Silicon nanowires were fabricated via metal-assisted chemical etching (MACE) with etching durations of 15, 25, 35, 45, and 60 min. The SiNWs etched for 15 min exhibited the highest sensitivity, showing superior electrochemical performance. Functionalized SiNWs were systematically evaluated for phosphate ion (HPO₄²⁻) detection over a wide concentration range (10⁻¹⁰ to 10⁻⁶ M) using Mott–Schottky measurements. The surface morphology of the SiNWs was thoroughly characterized before and after Cu (II) Pc-PAA layer functionalization. The sensing material was analyzed using contact angle goniometry and scanning electron microscopy (SEM), confirming both its uniform distribution and effective immobilization. The sensor displayed a Nernstian behavior with a sensitivity of 28.25 mV/Decade and an exceptionally low limit of detection (LOD) of 1.5 nM. Furthermore, the capacitive sensor exhibited remarkable selectivity toward phosphate ions, even in the presence of potentially interfering anions such as Cl⁻, NO₃⁻, SO₄²⁻ and ClO₄⁻. These results confirm the sensor’s high sensitivity, selectivity, and fast response, underscoring its suitability for environmental phosphate ion monitoring. Full article

A facile fabrication method was developed for the growth of Cu_1.8Se nanosheets (NSs) on a Cu foil substrate, enabling dual-functionality as an electrochemical sensor for H₂O₂ and an active surface-enhanced Raman scattering (SERS) substrate. The process involved the preparation of Cu(OH)₂ nanowires (NWs) via electrochemical oxidation, followed by chemical conversion to Cu_1.8Se through a selenization process. The morphology, composition, and microstructure of the resulting Cu_1.8Se NSs were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Cu_1.8Se NSs exhibited excellent electrocatalytic activity for H₂O₂ reduction, achieving a notably low detection limit of 1.25 μM and demonstrating rapid response and high sensitivity with a linear relationship in amperometric detection. Additionally, SERS experiments using Rhodamine B as a probe molecule and the Cu_1.8Se NS/Cu foil as a substrate displayed outstanding performance, with a detection limit as low as 1 μM. The flower-like structure of the Cu_1.8Se NSs exhibited linear dependence between analyte concentration and detection signals, along with satisfactory reproducibility in dual-sensing applications. These findings underscore the scalability and potential of this fabrication approach for advanced sensor development. Full article

The development of high-performance electrochromic materials demands innovative approaches to simultaneously control the nanoscale architecture and the electronic structure. We present a dual-modification strategy that synergistically combines copper doping with the Langmuir–Blodgett (LB) assembly to overcome the traditional performance trade-offs in tungsten oxide-based electrochromic systems. Cu-doped W₁₈O₄₉ nanowires with varying Cu concentrations (0–12 mol%) were synthesized hydrothermally and assembled into thin films via the LB technique, with LB precursors characterized by contact angle, surface tension, viscosity, and thermogravimetric-differential scanning calorimetry (TG-DSC) analyses. The films were systematically evaluated using scanning electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry, and transmittance spectroscopy. Experimental results reveal an optimal Cu-doping concentration of 8 mol%, achieving a near-infrared optical modulation amplitude of 76.24% at 1066 nm, rapid switching kinetics (coloring/bleaching: 5.0/3.0 s), and a coloration efficiency of 133.00 cm²/C. This performance is speculated to be a balance between Cu-induced improvements in ion intercalation kinetics and LB-ordering degradation caused by lattice strain and interfacial charge redistribution, while mitigating excessive doping effects such as structural deterioration and thermodynamic instability. The work establishes a dual-modification framework for designing high-performance electrochromic interfaces, emphasizing the critical role of surface chemistry and nanoscale assembly in advancing adaptive optoelectronic devices like smart windows. Full article

To meet the stringent demands of next-generation flexible optoelectronic devices, a novel fabrication approach is employed that integrates the spray-coating of copper nanowires (Cu NWs) with the magnetron sputtering of SrTiO₃ thin films, thereby yielding SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films. The incorporation of the SrTiO₃ layers results in improved optical performance, with the transmittance of the Cu NW network increasing from 83.5% to 84.2% and a concurrent reduction in sheet resistance from 16.9 Ω/sq to 14.5 Ω/sq. Moreover, after subjecting the hybrid thin films to 100 repeated tape-peeling tests and 2000 bending cycles with a bending radius of 5.0 mm, the resistance remains essentially unchanged, which underscores the films’ exceptional mechanical flexibility and robust adhesion. Additionally, the hybrid thin films are subjected to rigorous high-temperature, high-humidity, and oxidative conditions, where the resistance exhibits outstanding stability. These results substantiate the potential of the SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films for integration into flexible and wearable electronic devices, delivering enhanced optoelectronic performance and long-term reliability under demanding conditions. Full article

Electrocatalytic nitrate reduction reaction (NO₃⁻RR) to ammonia (NH₃) presents an alternative, sustainable approach to ammonia production. However, the existing catalysts suffer from poor NH₃ yield under lower concentrations of NO₃⁻, and the kinetic understanding of bimetal catalysis is lacking. In this study, a Co₃O₄–modified Cu₂₊₁O nanowire (CoCuNWs) catalyst with a high specific surface area was synthesized to effectively produce NH₃ from a 10 mM KNO₃ basic solution. CoCuNWs demonstrated a high NH₃ yield rate of 0.30 mmol h⁻¹ cm⁻² with an NH₃ Faradaic efficiency (FE) of 96.7% at −0.2 V vs. RHE, which is 1.5 times higher than the bare Cu₂₊₁O NWs. The synergistic effect between Co₃O₄ and Cu₂₊₁O significantly enhanced both the nitrate conversion and ammonia yield. Importantly, it is revealed that the surface of CoCuNWs is kinetically more easily saturated with NO₃⁻ (NO₂⁻) ions than that of Cu₂₊₁O NWs, as evidenced by both the higher current density and the plateau occurring at higher NO_x⁻ concentrations. In addition, CoCuNWs exhibit a higher diffusion coefficient of NO₃⁻, being 1.6 times higher than that of Cu₂₊₁O NWs, which also indicates that the presence of Co₃O₄ could promote the diffusion and adsorption of NO₃⁻ on CoCuNWs. Moreover, the ATR–SEIRAS analysis was applied to illustrate the reduction pathway of NO₃⁻ to NH₃ on CoCuNWs, which follows the formation of the key intermediate from *NO₂⁻, *NO, *NH₂OH to *NH₃. This work presents a strategy for constructing dual–metal catalysts for NO₃⁻RR and provides an insight to understand the catalysis from the perspective of the kinetics. Full article

Copper nanowires (Cu NWs) are considered a promising alternative to indium tin oxide (ITO) and silver nanowires (Ag NWs) due to their excellent electrical conductivity, mechanical properties, abundant reserves, and low cost. They have been widely applied in various optoelectronic devices. In this study, Cu NWs were synthesized using copper chloride (CuCl₂) as the precursor, monoethanolamine (MEA) as the complexing agent, and hydrated hydrazine (N₂H₄) as the reducing agent under strongly alkaline conditions at 60 °C. Notably, this is the first time that MEA has been employed as a complexing agent in this synthesis method for Cu NWs. Through a series of experiments, the optimal conditions for the CuCl₂–MEA–N₂H₄ system in Cu NWs synthesis were determined. This study revealed that the presence of amines plays a crucial role in nanowire formation, as the co-ordination of MEA with copper in this system provides selectivity for the nanowire growth direction. MEA prevents the excessive conversion of Cu(I) complexes into Cu₂O octahedral precipitates and exhibits an adsorption effect during Cu NWs formation. The different adsorption tendencies of MEA at the nanowire ends and lateral surfaces, depending on its concentration, influence the growth of the Cu NWs, as directly reflected by changes in their diameter and length. At an MEA concentration of 210 mM, the synthesized Cu NWs have an average diameter of approximately 101 nm and a length of about 28 μm. To fabricate transparent conductive films, the Cu NW network was transferred onto a polyethylene terephthalate (PET) substrate by applying a pressure of 20 MPa using a tablet press to ensure strong adhesion between the Cu NW-coated mixed cellulose ester (MCE) filter membrane and the PET substrate. Subsequently, the MCE membrane was dissolved by acetone and isopropanol immersion. The resulting Cu NW transparent conductive film exhibited a sheet resistance of 52 Ω sq⁻¹ with an optical transmittance of 86.7%. Full article

The development of micro glucose sensors plays a vital role in the management and monitoring of diabetes, facilitating real-time tracking of blood glucose levels. In this paper, we developed a three-layer core-sheath microwire (NW@CuO@Co₃O₄) with nickel wire as the core and copper oxide and cobalt oxide nanowires as the sheath. The unique core-sheath structure of microwire enables it to have both good conductivity and excellent electrochemical catalytic activity when used as an electrode for glucose detecting. The non-enzymatic glucose sensor base on a NW@CuO@Co₃O₄ core-sheath wire exhibits a high sensitivity of 4053.1 μA mM⁻¹ cm⁻², a low detection limit 0.89 μM, and a short response time of less than 2 s. Full article

An experimental characterization of cupric oxide nanowire (CuO NW) growth from thermally oxidized, microstructured Cu thin films is performed. We have systematically studied the influence of the thickness and dimension of Cu layers on the synthesis of CuO NW. The objective was to determine the optimum Cu geometries for increased CuO NWs growth to bridge the gap between adjacent Cu structures directly on the chip for gas sensing applications. Thresholds for CuO-NW growth regarding film thickness and lateral dimensions are identified based on SEM images. For a film thickness of 560 nm, NWs with lengths > 500 nm start to grow from the edges of Cu structures with an area ≥ 4 µm². NWs growing from the upper surface were observed for an area ≥ 16 µm². NW growth between adjacent thermally oxidized thin films was analyzed. The study provides information on the most relevant parameters of CuO NWs growth, which is mandatory for integrating CuO NWs as gas sensor components directly on microchips. Based on this result, the gap size of the structure was varied to find the optimum value of 3 µm. Full article

This study focuses on the growth of Cu₂O/CuO nanowires by one-step thermal oxidation using a flexible copper mesh at oxidation temperatures in the range of 300 to 600 °C in a controlled atmosphere of mixed-flow Ar and O₂ gases. Thermal oxidation is one of the simplest used methods to obtain nanowires on a metal surface, offering advantages such as low production costs and the ability to produce metal oxides on a large scale without the use of hazardous chemical compounds. The growth of metal oxides on a conductive substrate, forming metal/oxide structures, has proven to be an effective method for enhancing charge-transfer efficiency. The as-synthesized Cu/Cu₂O/CuO (Nw) electrodes were structurally and morphologically characterized using techniques such as XRD and SEM/EDX analysis to investigate the structure modification and morphologies of the materials. The supercapacitor properties of the as-developed Cu/Cu₂O/CuO (Nw) electrodes were then examined using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS). The CV curves show that the Cu/Cu₂O/CuO (Nw) structure acts as a positive electrode, and, at a scan rate of 5 mV s ⁻¹, the highest capacitance values reached 26.158 mF cm⁻² for the electrode oxidized at a temperature of 300 °C. The assessment of the flexibility of the electrodes was performed at various bending angles, including 0°, 45°, 90°, 135°, and 180°. The GCD analysis revealed a maximum specific capacitance of 21.198 mF cm⁻² at a low power density of 0.5 mA cm⁻² for the oxidation temperature of 300 °C. The cycle life assessment of the all of the as-obtained Cu/Cu₂O/CuO (Nw) electrodes over 500 cycles was performed by GCD analysis, which confirmed their electrochemical stability. Full article

Herein, a series of heterogeneous Fenton catalysts, Cu doped MnO₂ (CDM), with different Cu/Mn molar ratios were prepared via a hydrothermal reaction. Meanwhile, detailed characterizations were used to study the structures of CDM, and it is amazing that the morphology of CDM changed from nanowires to nanoflowers with an increasing amount of Cu doped. Apart from this, both the specific surface area and oxygen vacancy increased obviously with the increasing Cu/Mn molar ratio. Then, the degradation of different dyes was utilized to evaluate the catalytic activity of different CDM with H₂O₂ used as the oxidizing agent, and the 50%-CDM with the highest content of Cu doped displayed the best catalytic activity. Herein, the degradation efficiency (D%) of Congo red (CR) solution with low concentration (60 mg/L) reached 100% in 3 min, while the D% of CR solution with a high concentration (300 mg/L) reached 99.4% after 5 min with a higher dosage of H₂O₂. Additionally, the 50%-CDM also displayed excellent reusability, for which the D% values were still higher than 90% after the 14th cycles. Based on the structure characteristics and mechanism analysis, the excellent catalytic capacity of 50%-CDM was due to the combined influence of large specific surface area and abundant oxygen vacancy. Thus, a promising heterogeneous Fenton catalyst was developed in this study, which proved the treatment efficiency of actual dye wastewater. Full article

We have designed an excellent visible-light-driven and high-performance photocatalyst with a Ag-Cu₂O-ZnO nanowire heterostructure in our work by combining the hydrothermal approach with plasma–liquid technology. The structural and morphological characteristics and optical properties of the samples were evaluated using X-ray diffraction, field-emission scanning electron microscopy, and spectrophotometry, respectively. The results show that the Ag nanoparticles are mainly positioned on the Cu₂O nanoclusters compared with the ZnO nanowire surface, forming broccoli-like Ag-Cu₂O nanoclusters during the Ar gas plasma treatment process in an aqueous solution. The diameter of the Ag/Cu₂O nanoclusters ranges from 150 to 180 nm. The Ag-Cu₂O-ZnO nanowires exhibited improved photocatalytic performance, decomposing approximately 98% methyl orange dye in 30 min. This is a consequence of the synergistic interactions between the p-n heterojunction formed at the Cu₂O-ZnO interfaces and the localized surface plasmon resonance (LSPR) effect of the Ag nanoparticles, which broaden the visible light absorption range and effectively separate the photogenerated charge carriers. Full article