CuO2 Layers Research Articles

Oxygen evolution reaction enhancement of copper electrodes in alkaline medium using ultrafast femtosecond laser structuring

In the pursuit of enhancing the oxygen evolution reaction (OER) activity, we employed femtosecond (FS) laser-induced surface nano-structuring to extend the surface area of copper (Cu) electrodes. Compelling surface hierarchical microstructures have been generated on the electrode surface using this approach. By optimizing the laser processing parameters, regular arrays of conical microstructures are fully covered by a thick and porous layer of Cu2O. Electrochemical measurements reveal that FS laser structuring developed large and structure-tunable surface areas with relative roughness factor between 51 and 61. The enhanced surface area and FS laser-induced Cu2O layers significantly enhanced the OER activity leading to a reduced overpotential (η10 = 345 mV) that is 70% less than that of pristine Cu at a current density of 10 mA cm−2. The results demonstrate the effectiveness of femtosecond laser-based surface structuring in enhancing the electrocatalytic OER activity of Cu electrodes in alkaline media.

The Investigation of the Influence of a Cu2O Buffer Layer on Hole Transport Layers in MAPbI3-Based Perovskite Solar Cells.

The passivation engineering of the hole transport layer in perovskite solar cells (PSCs) has significantly decreased carrier accumulation and open circuit voltage (Voc) loss, as well as energy band mismatching, thus achieving the goal of high-power conversion efficiency. However, most devices incorporating organic/inorganic buffer layers suffer from poor stability and low efficiency. In this article, we have proposed an inorganic buffer layer of Cu2O, which has achieved high efficiency on lower work function metals and various frequently used hole transport layers (HTLs). Once the Cu2O buffer layer was applied to modify the Cu/PTAA interface, the device exhibited a high Voc of 1.20 V, a high FF of 75.92%, and an enhanced PCE of 22.49% versus a Voc of 1.12 V, FF of 69.16%, and PCE of 18.99% from the (PTAA/Cu) n-i-p structure. Our simulation showed that the application of a Cu2O buffer layer improved the interfacial contact and energy alignment, promoting the carrier transportation and reducing the charge accumulation. Furthermore, we optimized the combinations of the thicknesses of the Cu2O, the absorber layer, and PTAA to obtain the best performance for Cu-based perovskite solar cells. Eventually, we explored the effect of the defect density between the HTL/absorber interface and the absorber/ETL interface on the device and recommended the appropriate reference defect density for experimental research. This work provides guidance for improving the experimental efficiency and reducing the cost of perovskite solar cells.

TiO2:ZnO/CuO thin film solar cells prepared via reactive direct-current (DC) magnetron sputtering

TiO2:ZnO/CuO thin-film solar cells are manufactured using reactive direct-current magnetron sputtering. For the first time, the TiO2:ZnO layers have been used as an emitter in TiO2:ZnO/CuO solar cells by self-produced Ti-ZnO targets. The structural and morphological characterization of the TiO2:ZnO/CuO solar cells was studied using physical methods of investigation: X-ray diffraction (XRD), scanning electron microscopy (SEM), and current-voltage (I-V) characteristics. From the XRD study, thin films were observed in CuO, ZnO, TiO2 and Ti3O5 phases. Basic morphological characterizations like thickness, mechanism of growth, and average grain sizes were analyzed via scanning electron microscopy. The thicknesses of the TiO2:ZnO and CuO layers were in the range of 170 to 354 nm and from 508 to 1634 nm, respectively. Furthermore, average grain sizes of CuO layers were in the range of 40–150 nm. The I-V study confirms the photovoltaic behavior of TiO2:ZnO/CuO 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 49.0 mV and from 0.45 to 7.26 µA/cm3, respectively. Additionally, the authors calculated and analyzed the values of Pmax, Isc, FF, Rs and Rsh. Finally, the optical properties of the thin film were studied. The total light transmission through the structure does not exceed 25% and the absorption coefficient below 600 nm is in the range 2 × 104–2 × 105 cm−1. The maximum reflectance value is observed in the UV-visible region and does not exceed 42%. The extinction coefficient varies between 0.1 and 0.9 depending on the wavelength and sample. The refractive index at 400 nm depends on the sample and is in the range of 1.7 to 4.5. The obtained values of the optical band gap for the investigated samples are 1.02 eV, 1.25 eV, 1.26 eV and 1.28 eV.

Hidden magnetic texture in the pseudogap phase of high-Tc YBa2Cu3O6.6

Despite decades of intense research, the enigmatic pseudo-gap (PG) phase of superconducting cuprates remains unsolved. In the last 15 years, various symmetry breaking states were discovered in the PG phase, including an intra-unit cell (IUC) magnetism, which preserves the lattice translational (LT) symmetry but breaks the time-reversal and parity symmetries, and an additional incipient charge density wave breaking the LT symmetry. However, none of these states can (alone) account for the partial gapping of the Fermi surface. Here we report a hidden LT-breaking magnetism using polarized neutron diffraction. Our measurements reveal magnetic correlations, in two different underdoped YBa2Cu3O6.6 single crystals that set in at the PG onset temperature with (i) a planar propagation wave vector (π, 0) ≡ (0, π), yielding a doubling or quadrupling of the magnetic unit cell and (ii) magnetic moments mainly pointing perpendicular to the CuO2 layers. The LT-breaking magnetism is at short-range suggesting the formation of clusters of 5–6 unit cells. Together with the previously reported IUC magnetism, it yields a hidden magnetic texture of the CuO2 unit cells hosting loop currents, forming large supercells that may be helpful for elucidating the PG puzzle.

Understanding the Growth of Copper Oxide Nanowires and Layers by Thermal Oxidation over a Broad Temperature Range at Atmospheric Pressure

In this paper, we explore the development of copper oxide layers and their evolution into nanowires on thermally oxidized copper and underlying chemical processes governing the growth of unidirectional, one-dimensional copper oxide (CuO), especially focusing on the role of underlying oxide layers. Extensive experimental data sets of grown nanowires in an ambient atmosphere at different oxidation temperatures and times were collected, analysed, and correlated with theoretical modeling of growth processes. Detailed microstructural analysis revealed that upon annealing in air, the Cu2O layer of randomly oriented columnar grains forms first, followed by preferentially oriented CuO grains, evolving into CuO nanowires. Our results highlight the importance of copper and oxygen diffusion and concentration in equilibrium between Cu2O and CuO phases in the oxide film and indicate that CuO nanowires originate in twinned CuO grains, which elongate due to the twin boundary’s instability. With broad experimental data sets on growth conditions, we obtain the complete picture of experimental and modeled growth of copper oxide nanowires, which will enable the tailored design of nanowires and their implementation in catalysis, sensing, and other applications.

Magnetic Interaction in Doped 2D Perovskite Cuprates with Nanoscale Inhomogeneity: Lattice Nonlocal Effects vs. Superexchange

We have studied the superexchange interaction Jij in doped 2D cuprates. The AFM interaction strongly depends on the state of the lattice of a CuO2 layer surrounded by two LaO rock salt layers. In a static U and D stripe nanostructure, the homogeneous AFM interaction is impossible due to the U/D/U… periodic stripe sequence and TN=0. In a dynamic stripe nanostructure, the ideal CuO2 layer with nonlocal effects and the homogeneous AFM interaction are restored. However, the interaction Jij decreases by the exponential factor due to partial dynamic quenching. The meaning of the transition from the dynamic to the static cases lies in the spontaneous θ-symmetry breaking with respect to the rotation of all the tilted CuO6 octahedra by an orientation angle δθ=n·45° (where n=1÷4) in the U and D stripe nanostructure of the CuO2 layer. Moreover, the structural features help to study various experimental data on the charge inhomogeneity, Fermi level pinning in the p type cuprates only and time reversal symmetry breaking from a unified point of view.

(Digital Presentation) Electrodeposition of Free-Standing Porous Cu Frameworks for Energy Applications

Recently, a convenient method has been suggested to produce a highly porous metal structure such as Cu using a single-step electrodeposition method [1]. In this approach, hydrogen bubbles are used as dynamic templates during the metal electrodeposition process to create the micro-porous structure. However, the pore walls of the porous layers often grow in ramified dendritic structure, which results in limited mechanical stability and creates challenged for applications in compact devices.In this contribution, a novel approach will be discussed to improve the mechanical stability of these porous structures by employing a second electrodeposition step. This process greatly reduces the number of dendrites within the pore walls making the porous layer more compact and thus improving the mechanical stability significantly. Furthermore, a complete separation of the porous layer from the flat substrate can be achieved by ultrasonication to obtain a free-standing porous Cu framework. Some parameters such as the layer thicknesses and pore sizes can be tuned easily by changing the current density and the electrodeposition time, respectively.The use of thus prepared free-standing porous Cu frameworks will be discussed for photoelectrochemical (PEC) water splitting and CO2 reduction. For the PEC water splitting application, a photoactive Cu2O layer is electrodeposited on the free-standing porous Cu framework. A homogenous coating of the Cu2O can be achieved and the PEC performance shows a significant increase of photocurrents by more than 80 % at 0 V vs. RHE in comparison to the Cu2O planar substrate [2]. For the CO2 reduction application, a large sample with10 cm2 geometric surface area was successfully prepared. The sample was used in a custom-made electrochemical cell with a cation exchange membrane as a separator. CO2 gas in a high humidity environment is transported to the free-standing porous Cu working electrode via a membrane pump in a closed-loop system. Our preliminary results show formation of ethylene and ethane gas using gas chromatography which indicates a successful reduction reaction of the CO2.[1] H.C. Shin., M. Liu. Chem Mater 16:5460–5464 2004. Doi:10.1021/cm048887b[2] M. Kurniawan, M. Stich, M. Marimon, M. Camargo, R. Peipmann, T. Hannappel, A. Bund, J. Mater. Sci. 2021, Doi:10.1007/s10853-021-06058-y

Multifunctional double active layers formed with electrochemically controlled nanoparticle dispersion for resistive switching memory arrays

Expanding resistive random-access memory (RRAM) from a single device to an array requires a selector to suppress the sneak path and an external device to control the compliance current. Thus, a unique crossbar array that can be independently driven through the novel design of a multilayer RRAM structure with intelligently controlled Cu2O consisting of nanoparticles embedded in the amorphous matrix (ANPs) is proposed. The ANPs–Cu2O active layers are prepared by electrodeposition, and the negative shift of the deposition potential induces a higher density and smaller size of the nanoparticles. The ANPs–Cu2O films show different set voltages and extremely uniform reset voltages, and thus a functional double active layer (DAL) structure consisting of two ANPs–Cu2O layers with different set voltages is proposed. The electrochemically fabricated VCu-controlled DALs effectively protected the reverse current from the self-rectifying characteristics of a large forward/reverse current ratio, thus realizing selector-less RRAMs. In addition, the soft-breakdown showing filament formation in the upper layer reveals the saturation current step acting as a self-compliance current without the assistance of transistors. Finally, a 4 × 4 crossbar DAL RRAM array with transistor-less self-rectification is demonstrated, which shows excellent memory performance and endurance without interfering with adjacent cells.

Room-temperature DC-sputtered p-type CuO accumulation-mode thin-film transistors gated by HfO2

CuO grown by room-temperature direct current reactive magnetron sputtering is introduced to realize p-type thin-film transistors (TFTs) with a high-k HfO2 gate dielectric fabricated by atomic layer deposition. The devices work in an accumulation mode (AM) with two apparent threshold voltages corresponding to the formation of a buried channel and an accumulation layer, respectively. A CuO AM TFT with a channel length of 25 μm exhibit a competitive on-off ratio (Ion/Ioff) of 1.3 × 102, a subthreshold swing (SS) of 1.04 V dec−1, and a field-effect mobility (μFE) of 1.1 × 10−3 cm2 V−1 s−1 at room temperature. By measuring a CuO metal oxide semiconductor (MOS) capacitor at room temperature, a high acceptor doping density (NA) of ∼5 × 1017 cm−3, a high positive effective fixed surface charge density (Qf) of ∼9 × 1012 cm−2, and a low interfacial trap charge density (Dit) of ∼6 × 1010 eV−1 cm−2 at the HfO2/CuO interface are estimated. The μFE extracted from the accumulation regime appears lower than the Hall mobility measured for a similarly processed CuO layer on glass due to the increased hole concentration in CuO TFTs, compared to a Hall concentration of ∼1014 cm−3, following the MOS process. SS appears limited by the decreased channel to gate capacitance (Ccg) related to the buried channel in AM TFTs, parasitic capacitance to ground, and potentially very high interfacial traps at the non-passivated CuO/air interface.

Green Synthesis of Immobilized CuO Photocatalyst for Disinfection of Water

A green method for depositing a CuO layer with good adhesion and a large surface area on a support of activated alumina (Al2O3) was evaluated. The relatively simple method consists of adsorption of a copper salt on the surface of Al2O3, formation of Cu(OH)2, and subsequent decomposition of the hydroxide to CuO. The XRD confirmed that the deposited photocatalyst crystalized at low temperatures (80 °C). Furthermore, BET measurements show a surface area of about 90 m2/g. The large surface area is the result of the speed of the conversion and decomposition reactions. The photokilling properties of the prepared photocatalyst were evaluated using E. coli cells and the leaching of copper ions was determined using ICP-MS. The photocatalytic efficiency was also evaluated by the degradation of an organic azo dye. The prepared photocatalyst shows good activity in the purification and disinfection of treated water. The described method is economical, fast, and can be considered green, since the only byproducts are water and NaCl.

Influence of hole interface layer on the performance of cadmium telluride-based thin film solar cell

The numerical modeling of cadmium telluride (CdTe) thin-film solar cell employing p + Cu2O as the hole Interface Layer is presented in this study. SCAPS software was used to analyze the performance of ZnO/CdS/CdTe/Cu2O with different absorber layer thicknesses. Cuprous oxide (Cu2O) is used as a hole transport layer in the suggested structure. Efficiency (η) without Cu2O is 19.10 percent (with VOC = 0.81 V, JSC = 27.12 mA/cm2, FF = 86.01 percent) and efficiency (η) with Cu2O is 25.39 percent (with VOC = 1.11 V, JSC = 27.91 mA/cm2, FF = 83.53 percent) for ZnO/CdS/CdTe/Cu2O structure. The Cu2O layer minimizes recombination losses at the back contact, increasing the cell's efficiency. As a result, utilizing SCAPS to simulate the proposed cell is beneficial to understand photovoltaic devices.

Anomalous Ferromagnetism of quasiparticle doped holes in cuprate heterostructures revealed using resonant soft X-ray magnetic scattering

We report strong ferromagnetism of quasiparticle doped holes both within the ab-plane and along the c-axis of Cu-O planes in low-dimensional Au/d-La1.8Ba0.2CuO4/LaAlO3(001) heterostructures (d = 4, 8 and 12 unit-cells) using resonant soft X-ray and magnetic scattering together with X-ray magnetic circular dichroism. Interestingly, ferromagnetism is stronger at a hole doped peak and at an upper Hubbard band of O with spin-polarization degree as high as 40%, revealing strong ferromagnetism of Mottness. For in-ab-plane spin-polarizations, the spin of doped holes in O2p–Cu3d–O2p is a triplet state yielding strong ferromagnetism. For out-of-ab-plane spin-polarization, while the spins of doped holes in both O2p–O2p and Cu3d–Cu3d are triplet states, the spin of doped holes in Cu3d–O2p is a singlet state yielding ferrimagnetism. A ferromagnetic-(002) Bragg-peak of the doped holes is observed and enhanced as a function of d revealing strong ferromagnetism coupling between Cu-O layers along the c-axis.

Solid-phase epitaxy of a CuAlO2 template on c-Al2O3 for delafossite growth

Thin-film growth of ABO2 delafossites has recently attracted significant attention due to its attractive transport properties and potential applications. A fundamental requirement for achieving high-quality thin films is the availability of lattice matching substrates and chemical compatibility. However, there are still many obstacles to achieving high-quality thin films. Here, we report a process to further engineer a template ABO2 delafossite structure by solid-phase epitaxy of CuAlO2 on the surface of a commercial sapphire substrate, which offers a promising route to growing high-quality epitaxial thin films. The starting reagents involve a layer of polycrystalline Cu2O deposited on a c-Al2O3 substrate by pulsed laser deposition (PLD). Subsequent thermal treatment activates a solid-state interface reaction between the film and substrate, producing a CuAlO2 thin film. The reaction temperature and dwell time parameters were optimized in this study to prepare a phase diagram for CuAlO2 samples without phase impurities. This method provides an essential stepping-stone toward the approachability of a lattice matching template (i.e., substrate-buffer layer) for ABO2 heterostructures. An example of successful epitaxial growth of highly conducting PdCrO2 is also demonstrated by using a CuAlO2 buffer layer.

Restoring the surface layer of Bi2Sr2CaCu2O8+δ single crystals by current injection

In 2010, we reported a new method to electronically tailor the hole concentration of the high-Tc superconductor Bi2Sr2CaCu2O8+δ (Bi-2212). We discovered that current injection along the c-axis of Bi-2212 provides a convenient tool to reversibly increase the carrier concentration. In this study, we have investigated the current injection effect on the surface junction of Bi-2212 by a series of current injection experiments carried out in samples of slightly overdoped and of extremely underdoped Bi-2212 crystals. The c-axis transport characteristics of bulk and surface intrinsic Josephson junctions are examined in a wide range of doping by current injection. Before injection treatment, typically, our samples demonstrate non-superconducting characteristics across their surface junctions, because standard preparation procedures cause the topmost CuO2 layers to be heavily degraded by oxygen loss. The electronic doping enables to substantially restore the hole concentration of the topmost CuO2 layers. The contact resistance is significantly reduced, and the intrinsic junction at the surface gets back its superconducting tunneling characteristic. We examine systematically the doping results of surface and bulk junction stacks and discuss the enhancement of their superconducting properties.

Atomistic understanding of extreme strain shear deformation of Copper-Graphene composites

Copper-Graphene (Cu-Gr) composites demonstrate high strength, lubricity, and enhanced electrical and thermal conductivity compared to pure copper. A homogeneous dispersion of graphene/graphitic domains in Cu is highly desirable, which can be achieved by solid-state shear-assisted processing. A detailed understanding of structure evolution of Cu-Gr under deformation is needed. Here we subjected Gr coated Cu foils to high strain shear deformation using a tribometer to observe the distribution and reallocation of Gr in Cu matrix. A rupture and smearing of Gr layer into Cu were observed reducing the Cu grain size from 67 ± 14 μm to <10 nm, in maximum shear region close to surface. While a gradual strain accumulation further below resulted in grain rotations and dynamic recrystallization. During deformation, the Gr film was first observed to fracture into flakes and then embed into the Cu matrix. Graphitic domains observed in the Cu evinced the metastable composite microstructure with a sandwich layer of Cu2O on the interface. The local conductance, measured by conductive atomic force microscopy, shows a fivefold increase in Cu-Gr composite region compared to pure Cu. Our study shows the feasibility of shear processing to create fine-grained Cu-Gr composites with enhanced conductivity.

Atomic origin of the coexistence of high critical current density and high Tc in CuBa2Ca3Cu4O10+δ superconductors

For cuprate superconductors, a high critical transition temperature (Tc) can be realized in compounds containing multiple CuO2 layers in the unit cell, while a high critical current density (Jc) is rarely sustained above liquid nitrogen temperature. The CuBa2Ca3Cu4O10+δ (Cu-1234) superconductors synthesized under high oxygen pressure incredibly exhibit high Tc (~117 K) and high Jc (>104 A/cm2, 100 K) values. Here, the “double high” traits of Cu-1234 were investigated with advanced scanning transmission electron microscopy. It was revealed that ordering vacancies and plate-like 90° microdomains induced efficient microstructure pinning centers that suppressed vortex flux flow and enhanced Jc. Furthermore, metallic charge-reservoir blocks [Ba2CuO3+δ] were composed of unique compressed [CuO6] octahedra, which induced many holes with 2pz symmetry that significantly decreased the superconducting anisotropy and dramatically enhanced the interlayer coupling that guaranteed a high Jc. On the other hand, optimally doped CuO2 planes inside the thick superconducting blocks [Ca3Cu4O8] maintained a high Tc. Our results are applicable to design and synthesis of new superconductors with “double high” traits.

Finite element analysis of thermal stress in Cu2O coating synthesized on Cu substrate

The paper aims to find the magnitude and nature of thermal residual stresses that occur during cooling of a copper sample with a thermally synthesized oxide layer of Cu2O. Thermo-mechanical analysis was performed by the finite element method using Ansys Software. The results of thermal analysis were used to study the resulting stress-strain state of the thin film/coating system after cooling. Based on the modeling results, the paper determined the most stress-strain areas of the sample with a coating, which are the free edges of the interfaces between the copper substrate and the Cu2O oxide layer. The main limitations of the study are the use of certain simplifications in the condition setup, for instance, uniform cooling of the thin film/coating system, homogeneity and isotropy of substrate and thin film materials, invariance of their properties with temperature changes, etc. The results obtained can be used to control the stress-strain state of the thin film/coating system and prevent deformations and destruction of thin-film structures during their production and operation of products with them. The study of new promising methods for the formation of oxide nanostructures, for instance in a plasma environment, requires a sufficient theoretical basis in addressing the origin and development of stresses.

Modifying the Lithiophilicity of Cu 2 O/Cu Collector by LiCuO to Restrain Lithium Dendrite Growth

AbstractLithium dendrite growth has long been considered an obstacle to the practical application of lithium metal battery, which could be efficiently suppressed by increasing the lithiophilicity of Cu collector. Therefore, herein we developed a facile way to prepare LiCuO/Cu composite current collector, which shows better wettability with EC/EDC electrolyte than pure Cu2O layer. X‐ray diffraction (XRD) analysis shows that there is a large amount of LiCuO on the surface of the anode. The nucleation overpotential of LiCuO/Cu composite current collector is only 26 mV in the electrodeposition curve. At a current density of 1 mA/cm2, the Li−Cu cell with the as‐prepared LiCuO/Cu anode, can keep more than 85 % Coulombic efficiency for more than 125 cycles. Impedance spectra of electrodes image show that the impedance of LiCuO/Cu composite current collector is only 60 Ω at the initial stage, which can promote the transfer of Li+ at the collector surface and thus inhibit the formation of lithium dendrites on the electrode surface.

Graphene core–shell structure guided functionalized interface to prepare high-strength, high-plasticity, and high-conductivity copper matrix composites

Integration of excellent mechanical and electrical properties is the vital requirement for engineering application of copper matrix composites (CMCs). In this study, reduced graphene oxide-coated submicron spherical Cu (SSCu@rGO) core–shell structure as a composite reinforcement phase was used to reinforce CMCs (SSCu@rGO/Cu composites). A perfect balance among high strength, high plasticity, and high electrical conductivity (EC) was achieved. Notably, SSCu@rGO promoted the uniform distribution of rGO, and led to the reaction between the interface of rGO and Cu reacted to form an optimized interface structure containing Cu2O and Cu4O3 nanotransition layers with load transfer and coordinated deformation functions. A comparative study was conducted between 0.1 wt% rGO-coated SSCu reinforced CMCs (SSCu@0.1 wt%rGO/Cu composites) and 0.5 wt% rGO-coated SSCu reinforced CMCs (SSCu@0.5 wt%rGO/Cu composites). When the mass fraction of SSCu@0.1 wt%rGO was 30 wt%, the tensile strength (TS) and elongation (EL) were found to be 309 MPa and 55%, respectively, and the strength plastic product (UT) was as high as 16995 MPa%, which is 2 times that of pure Cu. The yield strength (YS) was 171 MPa, which is about 3 times that of pure Cu. The EC remains the same as that of pure Cu, both correspond to 93% IACS (International Annealed Copper Standard). Further, its strengthening mechanism including strength mechanism, plasticity mechanism, and EC mechanism was comprehensively and elaborately discussed. This study shows that the use of graphene and submicron metal to prepare composite reinforcement phases can lead to the achievement of excellent matching of high UT and high EC of CMCs.

Long-range superconducting proximity effect in nickel nanowires

When a ferromagnet is placed in contact with a superconductor, owing to incompatible spin order, the Cooper pairs from the superconductor cannot survive more than one or two nanometers inside the ferromagnet. This is confirmed in the measurements of ferromagnetic nickel (Ni) nanowires contacted by superconducting niobium (Nb) leads. However, when a 3 nm thick copper oxide (CuO) buffer layer made by exposing an evaporated or a sputtered 3 nm Cu film to air, is inserted between the Nb electrodes and the Ni wire, the spatial extent of the superconducting proximity range is dramatically increased from 2 to a few tens of nanometers. Scanning transmission electron microscope study confirms the formation of a 3 nm thick CuO layer when an evaporated Cu film is exposed to air. Magnetization measurements of such a 3 nm CuO film on a SiO2/Si substrate and on Nb/SiO2/Si show clear evidence of ferromagnetism. One way to understand the long-range proximity effect in the Ni nanowire is that the CuO buffer layer with ferromagnetism facilitates the conversion of singlet superconductivity in Nb into triplet supercurrent along the Ni nanowires.