Although copper is needed for living organisms at low concentrations, it is one of the pollutants that should be monitored along with other heavy metals. A novel and sustainable composite mineralizing sorbent based on MgO-CaO-Al₂O₃-SiO₂-CO₂ with nanosized adsorption centers was synthesized using natural calcium–magnesium carbonates and clay aluminosilicates for copper sorption. An organometallic modifier was added as a temporary binder and a source of inovalent ions participating in the reactions of defect formation and activated sintering. The sorbent-mineralizer samples of specified composition and properties showed irreversible sorption of Cu²⁺ ions by the ion exchange reactions Ca²⁺ ↔ Cu²⁺ and Mg²⁺ ↔ Cu²⁺. The topochemical reactions of the ion exchange 2OH⁻ → CO₃²⁻, 2OH⁻ → SO₄²⁻ and CO₃²⁻ → SO₄²⁻ occurred at the surface with formation of the mixed calcium–copper carbonates and sulfates structurally connected with aluminosilicate matrix. The reverse migration of ions to the environment is blocked by the subsequent mineralization of the newly formed interconnected aluminosilicate and carbonate structures. Full article

This article introduces a facile droplet-based microfluidic method for the preparation of Fe₃O₄-incorporated alginate hydrogel magnetic micromotors with variable shapes. By using droplet-based microfluidics and water diffusion, monodisperse (quasi-)spherical microparticles of sodium alginate and Fe₃O₄ (Na-Alg/Fe₃O₄) are obtained. The diameter varies from 31.9 to 102.7 µm with the initial concentration of Na-Alginate in dispersed fluid ranging from 0.09 to 9 mg/mL. Calcium chloride (CaCl₂) is used for gelation, immediately transforming Na-Alg/Fe₃O₄ microparticles into Ca-Alginate hydrogel microparticles incorporating Fe₃O₄ nanoparticles, i.e., Ca-Alg/Fe₃O₄ micromotors. Spherical, droplet-like, and worm-like shapes are yielded depending on the concentration of CaCl₂, which is explained by crosslinking and anisotropic swelling during the gelation. The locomotion of Ca-Alg/Fe₃O₄ micromotors is activated by applying external magnetic fields. Under the rotating magnetic field (5 mT, 1–15 Hz), spherical Ca-Alg/Fe₃O₄ micromotors exhibit an average advancing velocity up to 158.2 ± 8.6 µm/s, whereas worm-like Ca-Alg/Fe₃O₄ micromotors could be rotated for potential advancing. Under the magnetic field gradient (3 T/m), droplet-like Ca-Alg/Fe₃O₄ micromotors are pulled forward with the average velocity of 70.7 ± 2.8 µm/s. This article provides an inspiring and timesaving approach for the preparation of shape-variable hydrogel micromotors without using complex patterns or sophisticated facilities, which holds potential for biomedical applications such as targeted drug delivery. Full article

Interpenetrating bulk heterojunction (IBHJ) quantum dot solar cells (QDSCs) offer a direct pathway for electrical contacts to overcome the trade-off between light absorption and carrier extraction. However, their complex three-dimensional structure creates higher requirements for the optimization of their design due to their more difficult interface defect states control, more complex light capture mechanism, and more advanced QD deposition technology. ZnO nanowire (NW) has been widely used as the electron transport layer (ETL) for this structure. Hence, the optimization of the ZnO NW morphology (such as density, length, and surface defects) is the key to improving the photoelectric performance of these SCs. In this study, the morphology control principles of ZnO NW for different synthetic methods are discussed. Furthermore, the effects of the density and length of the NW on the collection of photocarriers and their light capture effects are investigated. It is indicated that the NW spacing determines the transverse collection of electrons, while the length of the NW and the thickness of the SC often affect the longitudinal collection of holes. Finally, the optimization strategies for the geometrical morphology of and defect passivation in ZnO NWs are proposed to improve the efficiency of IBHJ QDSCs. Full article

The beam splitter is a common and critical element in optical systems. Traditional beam splitters composed of prisms or wave plates are difficult to be applied to miniaturized optical systems because they are bulky and heavy. The realization of the nanoscale beam splitter with a flexible function has attracted much attention from researchers. Here, we proposed a polarization-insensitive beam splitter with a variable split angle and ratio based on the phase gradient metasurface, which is composed of two types of nanorod arrays with opposite phase gradients. Different split angles are achieved by changing the magnitude of the phase gradient based on the principle of Snell’s law of refraction, and different split ratios are achieved by adding a phase buffer with different areas. In the designed four types of beam splitters for different functions, the split angle is variable in the range of 12–29°, and the split ratio is variable in the range of 0.1–1. The beam splitter has a high beam splitting efficiency above 0.3 at the wavelength of 480–600 nm and a weak polarization dependence. The proposed beam splitter has the advantages of a small size and easy integration, and it can be applied to various optical systems such as multiplexers and interferometers for integrated optical circuits. Full article

Although power conversion efficiencies of organic-inorganic lead halide perovskite solar cells (PSCs) are approaching those of single-crystal silicon solar cells, the working device stability due to internal and external factors, such as light, temperature, and moisture, is still a key issue to address. The current world-record efficiency of PSCs is based on organic hole transport materials, which are usually susceptible to degradation from heat and diffusion of dopants. A simple solution would be to replace the generally used organic hole transport layers (HTLs) with a more stable inorganic material. This review article summarizes recent contributions of inorganic hole transport materials to PSC development, focusing on aspects of device performance and long-term stability. Future research directions of inorganic HTLs in the progress of PSC research and challenges still remaining will also be discussed. Full article

The high thermal conductivity and good insulating properties of boron nitride (BN) make it a promising filler for high-performance polymer-based thermal management materials. An easy way to prepare BN-polymer composites is to directly mix BN particles with polymer matrix. However, a high concentration of fillers usually leads to a huge reduction of mechanical strength and optical transmission. Here, we propose a novel method to prepare polyethylene/boron nitride nanoplates (PE/BNNPs) composites through the combination of electrostatic self-assembly and hot pressing. Through this method, the thermal conductivity of the PE/BNNPs composites reach 0.47 W/mK, which gets a 14.6% improvement compared to pure polyethylene film. Thanks to the tight bonding of polyethylene with BNNPs, the tensile strength of the composite film reaches 1.82 MPa, an increase of 173.58% compared to that of pure polyethylene film (0.66 MPa). The fracture stress was also highly enhanced, with an increase of 148.44% compared to pure polyethylene film. Moreover, the addition of BNNPs in PE does not highly reduce its good transmittance, which is preferred for thermal management in devices like light-emitting diodes. This work gives an insight into the preparation strategy of transparent and flexible thermal management materials with high thermal conductivity. Full article

With the demand for low contact resistance and a clean interface in high-performance field-effect transistors, two-dimensional (2D) hetero-phase homojunctions, which comprise a semiconducting phase of a material as the channel and a metallic phase of the material as electrodes, have attracted growing attention in recent years. In particular, MoTe₂ exhibits intriguing properties and its phase is easily altered from semiconducting 2H to metallic 1T′ and vice versa, owing to the extremely small energy barrier between these two phases. MoTe₂ thus finds potential applications in electronics as a representative 2D material with multiple phases. In this review, we briefly summarize recent progress in 2D MoTe₂ hetero-phase homojunctions. We first introduce the properties of the diverse phases of MoTe₂, demonstrate the approaches to the construction of 2D MoTe₂ hetero-phase homojunctions, and then show the applications of the homojunctions. Lastly, we discuss the prospects and challenges in this research field. Full article

We report the first direct synthesis of graphene on SiO₂/Si by hot-filament chemical vapor deposition. Graphene deposition was conducted at low pressures (35 Torr) with a mixture of methane/hydrogen and a substrate temperature of 970 °C followed by spontaneous cooling to room temperature. A thin copper-strip was deposited in the middle of the SiO₂/Si substrate as catalytic material. Raman spectroscopy mapping and atomic force microscopy measurements indicate the growth of few-layers of graphene over the entire SiO₂/Si substrate, far beyond the thin copper-strip, while X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy showed negligible amounts of copper next to the initially deposited strip. The scale of the graphene nanocrystal was estimated by Raman spectroscopy and scanning electron microscopy. Full article

Bi_1−xSm_xFe_0.98Mn_0.02O₃ (x = 0, 0.02, 0.04, 0.06; named BSFMx) (BSFM) films were prepared by the sol-gel method on indium tin oxide (ITO)/glass substrate. The effects of different Sm content on the crystal structure, phase composition, oxygen vacancy content, ferroelectric property, dielectric property, leakage property, leakage mechanism, and aging property of the BSFM films were systematically analyzed. X-ray diffraction (XRD) and Raman spectral analyses revealed that the sample had both R3c and Pnma phases. Through additional XRD fitting of the films, the content of the two phases of the sample was analyzed in detail, and it was found that the Pnma phase in the BSFMx = 0 film had the lowest abundance. X-ray photoelectron spectroscopy (XPS) analysis showed that the BSFMx = 0.04 film had the lowest oxygen vacancy content, which was conducive to a decrease in leakage current density and an improvement in dielectric properties. The diffraction peak of (110) exhibited the maximum intensity when the doping amount was 4 mol%, and the minimum leakage current density and a large remanent polarization intensity were also observed at room temperature (2Pr = 91.859 μC/cm²). By doping Sm at an appropriate amount, the leakage property of the BSFM films was reduced, the dielectric property was improved, and the aging process was delayed. The performance changes in the BSFM films were further explained from different perspectives, such as phase composition and oxygen vacancy content. Full article

In recent years, nanosized spinel-type ferrites emerged as an important class of nanomaterials due to their high electrical resistivity, low eddy current loss, structural stability, large permeability at high frequency, high coercivity, high cubic magnetocrystalline anisotropy, good mechanical hardness, and chemical stability [...] Full article

A suitable dispersion of carbon materials (e.g., carbon nanotubes (CNTs)) in an appropriate dispersant media, is a prerequisite for many technological applications (e.g., additive purposes, functionalization, mechanical reinforced materials for electrolytes and electrodes for energy storage applications, etc.). Deep eutectic solvents (DES) have been considered as a promising “green” alternative, providing a versatile replacement to volatile organic solvents due to their unique physical-chemical properties, being recognized as low-volatility fluids with great dispersant ability. The present work aims to contribute to appraise the effect of the presence of MWCNTs and Ag-functionalized MWCNTs on the physicochemical properties (viscosity, density, conductivity, surface tension and refractive index) of glyceline (choline chloride and glycerol, 1:2), a Type III DES. To benefit from possible synergetic effects, AgMWCNTs were prepared through pulse reverse electrodeposition of Ag nanoparticles into MWCNTs. Pristine MWCNTs were used as reference material and water as reference dispersant media for comparison purposes. The effect of temperature (20 to 60 °C) and concentration on the physicochemical properties of the carbon dispersions (0.2–1.0 mg cm⁻³) were assessed. In all assessed physicochemical properties, AgMWCNTs outperformed pristine MWCNTs dispersions. A paradoxical effect was found in the viscosity trend in glyceline media, in which a marked decrease in the viscosity was found for the MWCNTs and AgMWCNTs materials at lower temperatures. All physicochemical parameters were statistically analyzed using a two-way analysis of variance (ANOVA), at a 5% level of significance. Full article

Metal–organic frameworks (MOFs)-derived materials with a large specific surface area and rich pore structures are favorable for catalytic performance. In this work, MOFs are successfully prepared. Through pyrolysis of MOFs under nitrogen gas, zinc-based catalysts with different active sites for acetylene acetoxylation are obtained. The influence of the oxygen atom, nitrogen atom, and coexistence of oxygen and nitrogen atoms on the structure and catalytic performance of MOFs-derived catalysts was investigated. According to the results, the catalysts with different catalytic activity are Zn-O-C (33%), Zn-O/N-C (27%), and Zn-N-C (12%). From the measurements of X-ray photoelectron spectroscopy (XPS), it can be confirmed that the formation of different active sites affects the electron cloud density of zinc. The electron cloud density of zinc affects the ability to attract CH₃COOH, which makes catalysts different in terms of catalytic activity. Full article

In the past decade, perovskite materials have attracted great scientific and technological interest due to their interesting opto-electronic properties. Nanostructuring of the perovskites, due to their reduced dimensions are advantageous in offering large surface area, controlled transport and charge carrier mobility, strong absorption and photoluminescence, and confinement effects. These features, together with the unique tunability in composition, shape, and functionalities in addition to the ability to form efficient, low-cost, and light-active structures make the perovskite nanostructures efficient functional components for multiple applications, ranging from photovoltaics and batteries to lasing and light-emitting diodes. The purpose of this Special Issue is to give an overview of the latest experimental findings concerning the tunability in composition, shape, functionalities, growth conditions, and synthesis procedures of perovskite structures and to identify the critical parameters for producing materials with functional characteristics. Full article

Polymer nanodielectrics characterized by good flexibility, processability, low dielectric loss and high dielectric permittivity are materials of interest for wearable electronic devices and intelligent textiles, and are highly in demand in robotics. In this study, an easily scalable and environmentally friendly method was applied to obtain polysiloxane/nanosilica nanocomposites with a large content of nanofiller, of up to 30% by weight. Nanosilica was dispersed both as individual particles and as agglomerates; in nanocomposites with a lower amount of filler, the former prevailed, and at over 20 wt% nanosilica the agglomerates predominated. An improvement of both the tensile strength and modulus was observed for nanocomposites with 5–15 wt% nanosilica, and a strong increase of the storage modulus was observed with the increase of nanofiller concentration. Furthermore, an increase of the storage modulus of up to seven times was observed in the nanocomposites with 30 wt% nanosilica. The tensile modulus was well fitted by models that consider the aggregation of nanoparticles and the role of the interface. The dielectric spectra showed an increase of the real part of the complex relative permittivity with 33% for 30 wt% nanosilica in nanocomposites at a frequency of 1 KHz, whereas the loss tangent values were lower than 0.02 for all tested nanodielectrics in the radio frequency range between 1 KHz and 1 MHz. The polysiloxane–nanosilica nanocomposites developed in this work showed good flexibility; however, they also showed increased stiffness along with a stronger dielectric response than the unfilled polysiloxane, which recommends them as dielectric substrates for wearable electronic devices. Full article