Impact of gamma irradiation on physico-chemical and electromagnetic interference shielding properties of Cu2O nanoparticles reinforced LDPE nanocomposite films

In the current work, cuprous oxide (Cu2O) nanoparticles coated with Tween 80 were successfully synthesized via the chemical reduction method. Nanocomposites composed of low-density polyethylene (LDPE) and different ratios of Cu2O nanoparticles were fabricated by the melt mixing process. 10% of ethyl vinyl acetate (EVA) as a compatibilizing agent was added to the molten LDPE matrix and the mixing process continued until homogenous nanocomposites were fabricated. To study the influence of ionizing radiation on the fabricated samples, the prepared species were exposed to 50 and 100 kGy of gamma rays. The synthesized Cu2O nanoparticles were investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD and TEM analysis illustrated the successful formation of spherical Cu2O nanoparticles with an average size of 16.8 nm. The as-prepared LDPE/Cu2O nanocomposites were characterized via different techniques such as mechanical, thermal, morphological, XRD, and FTIR. Electromagnetic interference shielding (EMI) of the different nanocomposite formulations was performed as a promising application for these materials in practical life. The electromagnetic shielding effectiveness (SE) of the produced samples was measured in the X-band of the radio frequency range from 8 to 12 GHz using the vector network analyzer (VNA) and a proper waveguide. All the samples were studied before and after gamma-ray irradiation under the same conditions of pressure and temperature. The shielding effectiveness increased significantly from 25 dB for unirradiated samples to 35 dB with samples irradiated with 100 kGy, which reflects 40% enhancement in the effectiveness of the shielding.

Tuned MWCNT/CuO/Fe3O4/Polyaniline nanocomposites with exceptional microwave attenuation and a broad frequency band

In this study, novel quaternary MWCNT/CuO/Fe₃O₄/PANI nanocomposites were synthesized with three different weight ratios of CuO/Fe₃O₄/PANI to MWCNT (1:3), (1:4), and (1:5), where all of its components were synthesized separately and then combined in specific weight ratios. CuO/Fe₃O₄/PANI transmission electron microscopy (TEM) images revealed that most nanoparticles were in a CuO/Fe₃O₄ hybrid form, with a narrow size distribution uniformly dispersed in a polymer background. The TEM and scanning electron microscopy (SEM) images of the MWCNT/CuO/Fe₃O₄/PANI nanocomposite revealed that the MWCNT was uniformly coated with CuO/Fe₃O₄/PANI. All three nanocomposites samples demonstrated superior microwave attenuation performance in terms of reflection loss and absorption bandwidth. The minimum reflection losses for MWCNT/CuO/Fe₃O₄/PANI nanocomposites (1:3), (1:4), and (1:5) were 45.7, 58.7, and 85.4, 87.4 dB, respectively. The absorption bandwidths (RL ≤ −10 dB) of MWCNT/CuO/Fe₃O₄/PANI nanocomposites (1:3), (1:4), and (1:5) were 6, 7.6, and 6 GHz, respectively.

Transformation of Nanostructures Cu2O to Cu3Se2 through Different Routes and the Effect on Photocatalytic Properties

In this work, copper selenide (Cu₃Se₂ umangite phase) was synthesized by two routes, using a chemical reaction and the hydrothermal method to obtain CuSe-A and CuSe-H, respectively. The synthesis of Cu₃Se₂ consisted of a three-step process: in the first step, copper(I) oxide hexapods (Cu₂O) were obtained as the copper reservoir; in the second step, selenium ions were obtained from the reduction of selenium powder; and in the third step involves mixing two precursors following the two synthesis routes mentioned before. Analysis of X-ray diffraction and X-ray photoelectron spectroscopy showed the formation of the Cu₃Se₂ phase by both synthesis routes. On the other hand, using the scanning electron microscopy (SEM) technique, it is observed that the Cu₃Se₂ sample (CuSe-A) is obtained by exchanging in solution with agitation and that the copper selenium phase grows only on the surface of the hexapods. Meanwhile, the hydrothermal route promotes a total conversion of copper(I) oxide hexapods to the copper selenide phase (CuSe-H). The resulting materials were tested as photocatalytic materials to remove methylene blue dye in water under sunlight irradiation. Cu₃Se₂ (CuSe-H) obtained by the hydrothermal route exhibited a higher efficiency of photodegradation of dye, reaching a removal percentage of 92% after 4 h under sunlight.

Stabilization and Mineralization Mechanism of Cd with Cu-Loaded Attapulgite Stabilizer Assisted with Microwave Irradiation

Cadmium (Cd) in soil was stabilized using copper loaded attapulgite (Cu/ATP) in a microwave (MW) system. Excellent Cd stability in soil was achieved with Cu/ATP addition due to higher adsorption energy (1.38 eV) of Cu/ATP for Cd than that of ATP (∼1 eV), confirmed by density functional theory calculations. The strong hybridization of the s, p-orbitals of Cd with the s, p, d-orbitals of Cu on ATP contributed to the strong interactions between Cd and Cu/ATP. The stability performance of Cd in Cu/ATP-treated soil was further enhanced after MW irradiation through a series of phase transformation to more stable Cd-bearing crystalline minerals. The transformation was initiated by MW-induced "hot spots", which created cationic vacancy on Cu/ATP surface and enhanced the solid-state reactions between Cd and Cu/ATP framework. The total bond orders of Cd in the formed CdAl₄O₇ crystalline mineral elevated to 3.38, which was 5-fold higher than that for Cd on Cu/ATP, ensuring the long-term stability of Cd even after 360 curing days. Cd contaminated soil from a former industrial electroplating site was successfully stabilized with the proposed strategy. The research provides an effective stabilization strategy as well as a comprehensive understanding of the mechanism of long-term Cd stabilization.

Facile design of a ZnO nanorod–Ni core–shell composite with dual peaks to tune its microwave absorption properties

The Ni/ZnO composites show two wide attractive absorption bands, which could broaden the effective absorption bandwidth.

Facile solvothermal synthesis of novel hetero-structured CoNi–CuO composites with excellent microwave absorption performance

Novel hetero-structured CoNi–CuO composite microspheres with excellent microwave absorption performance were fabricated via a facile solvothermal pathway.

Yolk-Shell Ni@SnO2 Composites with a Designable Interspace To Improve the Electromagnetic Wave Absorption Properties

In this study, yolk-shell Ni@SnO₂ composites with a designable interspace were successfully prepared by the simple acid etching hydrothermal method. The Ni@void@SnO₂ composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicate that interspaces exist between the Ni cores and SnO₂ shells. Moreover, the void can be adjusted by controlling the hydrothermal reaction time. The unique yolk-shell Ni@void@SnO₂ composites show outstanding electromagnetic wave absorption properties. A minimum reflection loss (RL_min) of -50.2 dB was obtained at 17.4 GHz with absorber thickness of 1.5 mm. In addition, considering the absorber thickness, minimal reflection loss, and effective bandwidth, a novel method to judge the effective microwave absorption properties is proposed. On the basis of this method, the best microwave absorption properties were obtained with a 1.7 mm thick absorber layer (RL_min= -29.7 dB, bandwidth of 4.8 GHz). The outstanding electromagnetic wave absorption properties stem from the unique yolk-shell structure. These yolk-shell structures can tune the dielectric properties of the Ni@air@SnO₂ composite to achieve good impedance matching. Moreover, the designable interspace can induce interfacial polarization, multiple reflections, and microwave plasma.

Facile Synthesis of Novel Heterostructure Based on SnO2 Nanorods Grown on Submicron Ni Walnut with Tunable Electromagnetic Wave Absorption Capabilities

In this work, the magnetic-dielectric core-shell heterostructure composites with the core of Ni submicron spheres and the shell of SnO2 nanorods were prepared by a facile two-step route. The crystal structure and morphology were investigated by X-ray diffraction analysis, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). FESEM and TEM measurements present that SnO2 nanorods were perpendicularly grown on the surfaces of Ni spheres and the density of the SnO2 nanorods could be tuned by simply varying the addition amount of Sn(2+) in this process. The morphology of Ni/SnO2 composites were also determined by the concentration of hydrochloric acid and a plausible formation mechanism of SnO2 nanorods-coated Ni spheres was proposed based on hydrochloric acid concentration dependent experiments. Ni/SnO2 composites exhibit better thermal stability than pristine Ni spheres based on thermalgravimetric analysis (TGA). The measurement on the electromagnetic (EM) parameters indicates that SnO2 nanorods can improve the impedance matching condition, which is beneficial for the improvement of electromagnetic wave absorption. When the coverage density of SnO2 nanorod is in an optimum state (diameter of 10 nm and length of about 40-50 nm), the optimal reflection loss (RL) of electromagnetic wave is -45.0 dB at 13.9 GHz and the effective bandwidth (RL below -10 dB) could reach to 3.8 GHz (12.3-16.1 GHz) with the absorber thickness of only 1.8 mm. By changing the loading density of SnO2 nanorods, the best microwave absorption state could be tuned at 1-18 GHz band. These results pave an efficient way for designing new types of high-performance electromagnetic wave absorbing materials.

Recent advances in hybrid Cu2O-based heterogeneous nanostructures

Hybrid Cu2O-based heterogeneous nanostructures possess novel synergistic properties that arise from the integrated interaction between the disparate components, thereby showing promising potential for various important applications including solar cells, carbon monoxide oxidation, photocatalysts, field emission, sensors, templates and so on. With the rapid progress in nanomaterials science and nanotechnology, hybrid Cu2O-based heterogeneous nanostructures with well-controlled compositions, shapes and sizes have been rationally designed and synthesized. This review attempts to summarize the important advances in the development of different types of hybrid Cu2O-based heterogeneous nanostructures, such as hybrid Cu2O-metal nanostructures, hybrid Cu2O-metal oxide nanostructures and hybrid Cu2O-carbon nanostructures. The correlations between the improved performances and interfacial structures of the hybrid Cu2O-based heterogeneous nanostructures are discussed based on some important and representative examples. Several key scientific issues and perspective research directions in this field are also given.

Facile synthesis of crumpled ZnS net-wrapped Ni walnut spheres with enhanced microwave absorption properties

The microwave absorption properties of the ultra-thin and crumpled ZnS net-wrapped walnut-like Ni composites are superior to those of pristine Ni walnuts.

Ultrasmall superparamagnetic Ni nanoparticles embedded in polyaniline as a lightweight and thin microwave absorber

In this work, we have reported the preparation and lightweight and thin microwave absorbent application of ultrasmall Ni nanoparticles embedded in polyaniline (PANI).

Investigation of the electromagnetic absorption properties of Ni@TiO2 and Ni@SiO2 composite microspheres with core–shell structure

The core–shell Ni–SiO₂ composite exhibits the best electromagnetic wave absorption in the GHz range with a minimum reflection loss of −40.0 dB, which is superior to those of Ni–TiO₂ and Ni microspheres.

Facile synthesis and enhanced microwave absorption properties of novel hierarchical heterostructures based on a Ni microsphere–CuO nano-rice core–shell composite

The microwave absorption properties of a core–shell rice-like CuO-coated Ni composite are superior to those of pure Ni microspheres and CuO nanoflakes. The optimal reflection loss is −62.2 dB at 13.8 GHz.

ZnS nanowall coated Ni composites: facile preparation and enhanced electromagnetic wave absorption

The microwave absorption properties of ultrathin ZnS wall-coated Ni composites were superior to those of Ni microspheres and ZnS particles.