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The exploitation of multicomponent nanocomposites with suitable hierarchical heterostructures is an attractive strategy to obtain high performance microwave absorption materials. In this work, a versatile strategy is proposed for synthesizing 1D hierarchical core-shell structure with Co-ZIF arrays derived carbon nanotubes (CNTs) coupled on cotton fiber (CF)-supported MXene shell (Co/CNTs-MXene@CF). The advantages of Co-ZIF arrays derived CNTs and MXene dielectric layer can be efficiently integrated to realize multiple electron transfer paths by the construction of the well-designed hierarchical structure. The designed heterogeneous composites consist of the interlayer MXene and CNTs grow sequentially from the outermost Co-ZIF nanosheet arrays with appropriate conductivity and abundant heterointerfaces, which can improve the conduction loss and interfacial polarization response. As expected, the elaborate 1D Co/CNTs-MXene@CF heterostructures exhibit the optimal reflection loss of −61.41 dB at 2.52 mm and effective absorption bandwidth reaches 5.04 GHz with a thickness of only 1.5 mm. The experimental results demonstrate that the optimized structure dramatically improves the electromagnetic wave attenuation behavior. This work illuminates a new design strategy for the preparation of multicomponent composites with reasonable hierarchical structure that enables high-performance microwave absorption materials.

Graphene-based metal-free aerogel is desirable for lightweight electromagnetic wave (EMW) absorbing materials. However, the weak van-der-Waals combination between graphene sheets, accompanied by the repulsion from surface oxygen-related polar groups, significantly hinder the transfer of electrons between the sheets, and lead to poor mechanical strength. These become bottlenecks for the further improvement of EMW absorption and have a huge impact on achieving multi-functions. Here, we used an iodine modification strategy to fabricate reduced graphene oxide (RGO) aerogel, in which graphene sheets are bridged by iodine cations (I+). Meanwhile, iodine promotes the conversion of epoxy groups to hydroxyl groups on graphene, thereby facilitating the adhension of I+ on the surface. These iodine cations rather than iodine anions are essential to strengthen the interconnection between graphene sheets, which enables the RGO aerogel to exhibit higher electrical conductivity, larger mechanical strength, higher thermal stability, and significantly improved EMW absorbing capability. With the improvement in conduction loss and impedance matching, the iodine-bridged RGO aerogel exhibits a maximium reflection loss of −52.8 dB and an effective absorption bandwidth of 7.2 GHz at 2 wt% filler loading, which are 3.8 and 1.5 times of pure RGO, respectively. Besides, the improved mechanical strength and resistance to temperature change benefit expanding the application fields of this aerogel.

Composition and structural design play a very influential role in the microwave absorption (MA) manipulation of ferrite/carbon composites. Here, by carefully choosing the dimensionality of the bio-carbon materials, the interfacial geometries and MA properties of ferrite/bio-carbon composites have been controlled effectively. The one dimensional (1D), two dimensional (2D), and three dimensional (3D) biomass-based carbon materials decorated with ZnFe2O4 (ZFO) particles were obtained respectively from carbon fibers (1D), tree leaves (2D), wheat straw (2D), peanut shell (3D) and orange peel (3D) by a simple two-step synthesis method. With increasing the bio-carbon's dimensionality from 1D, 2D to 3D, the ferrite/carbon composite's MA properties are promoted and the minimum reflection loss is enhanced from −9 dB to −45 dB. By changing the ZFO/3D-bio-carbon samples' thickness, a broad absorption range from 4 to 18 GHz can be covered. Moreover, the effective absorption bandwidth for ZFO/3D-bio-carbon can be modified up to 7.1 GHz, which covers the whole Ku band. These observations identified the important roles of the ferrite/carbon interface and dimensionality of carbon materials and provided an effective and low-cost route to design microwave absorption materials based on biomass-industrial waste composites.

Utilization of biomass waste and solid industrial waste, one of the basic solutions of green economy, has become an important topic in both chemical and materials science. Individual bio-carbon, magnetic oxides, and their composites have been used in making microwave absorbers. Here, by utilizing coffee waste bio-carbon and industrial waste MnFe2O4 particles, an efficient microwave absorber has been realized based on their composites. The microwave absorption performance as well as the magnetization of as-synthesized composites can be tuned by adjusting the particle size of MnFe2O4. The minimum reflection loss (RLmini) can be enhanced around 5 times from -7.7 dB to -38.80 dB at 9.8 GHz when mean particle size of MnFe2O4 in the composites is reduced from 9.7 down to 0.9 μm. Meanwhile, a wide effective absorption bandwidth (7.8–11.4 GHz) is achieved in this bio-industrial-waste composite. Such enhancement is explained from viewpoint of appropriate impedance matching as well as the synergetic effect between the bio-carbon and the MnFe2O4. Our work provides a route for the utilization of bio-carbon waste and industrial magnetic waste in the field of microwave absorption.

Developing lightweight and inexpensive absorbents with strong and broadband absorbing performance toward microwave radiation is a challenging but pressing task. Here we report that rice husk-derived silica-hybridized holey carbon fabricated by combining pyrolysis and plasma processing methods is active for the microwave absorbing. The obtained metal-free product is barely prepared from wasted biomass without any additive reagents addition. The results demonstrate at the thickness of 1.5 mm, its reflection loss reaches −43.0 dB at 13.36 GHz and the corresponding absorption bandwidth approaches 3.68 GHz (from 11.44 GHz to 15.12 GHz), over-performing most bare biomass-derived absorbents. The enhanced performance is attributed to the silica blocks existing on surface, which is inherited from the raw rice husk precursor and will construct abundant hybridized contact sites with the derived carbon matrix, thereby providing plenty of interfacial polarizations. Meanwhile, the post plasma treatment can generate rich tiny holes on the carbon matrix, and endow it with high surface areas associated with a great variety of defective sites, and hence regulating the dielectric loss of the final product. It is anticipated that these can represent a feasible addition to the family of wasted biomass-derived sustainable microwave absorbents.

Metal-free graphene-based nanocomposites with small organic molecules interaction are studied as a lightweight, wide bandwidth, and strong absorption microwave absorption material. During hydrothermal process, graphene oxide (GO) precursors are reduced and aggregated into 3D porous network structure. Meanwhile, anthraquinone molecules are intercalated and immobilized on RGO surface through noncovalent π–π stacking. For the obtained RGO@anthraquinone, noncovalent functionalization at interface can modify the electronic states and regulate the electrical conductivity of graphene substrate and its sheet-like structure can be largely maintained. Integrating the intrinsic 3D porous structure, good impedance matching, high conductive loss, and noncovalent interaction, the as-achieved RGO@anthraquinone composites exhibit excellent microwave absorption performance in the X and Ku band. Such as RGO@2-hydroxyanthraquinone (2-HAQ), its optimal absorption toward microwave can reach −54.2 dB at 12.8 GHz with a thickness of 3.0 mm, and its effective absorption bandwidth lower than −10 dB exceeds 7.0 GHz (from 10.96 to 18.0 GHz). When the thickness is controlled between 2.8 and 3.5 mm, the effective absorption bandwidth can cover the whole X and Ku bands (8.0–18.0 GHz). This opens ways to achieve new microwave absorbers with high-performance and provides more opportunities to activate MA behavior on carbon-based metal-free absorbers.

High magnetic field effects on the microstructure and magnetic properties of BaFe 12 O 19 hexaferrites synthesized hydrothermal method have been investigated. The obtained results indicate that the lattice constant decreases gradually as the magnetic field strength increases, which may be attributed to the lattice distortion resulted from the high magnetic field. Polycrystalline BaFe 12 O 19 samples prepared under magnetic field strength at zero and 5 T are single phase. It is found that application of external magnetic field during synthesis can induce orientated growth of the hexaferrite crystals along the easy magnetic axis. The magnetic properties can be effectively regulated by an application of high magnetic fields. It is observed that the BaFe 12 O 19 prepared under a 5 T magnetic field exhibits a higher room-temperature saturation magnetization (66.3 emu/g) than that of the sample (43.6 emu/g) obtained without magnetic field. The results can be explained as the enhanced crystalline, improvement of Fe 3+ ions occupancy and the oriented growth induced by the external magnetic field. The growing orientation of particles gives rise to increased coercivity due to the enhancement in shape anisotropy. It is expected that an application of magnetic field during the formation of magnetic nanoparticles could be a promising technique to modify magnetic properties with excellent performance.

In this article, the CoFe2O4/MoS2 composites have been well constructed via a facial hydrothermal method, from which the porous CoFe2O4 microspheres were embedded into MoS2 ultrathin nanosheets. As a typical two-dimensional transition metal sulfide, MoS2 with high electrical conductivity and flexible properties is expected to exhibit high dielectric loss and magnetic loss when combined with magnetic material CoFe2O4. Meanwhile, the unique hierarchical structure of as-synthesized MoS2 nanoflowers is conducive to scattering and reflection of electromagnetic waves, and endows designed composites with competitive microwave absorption properties. Notably, although the saturation magnetization of MoS2/CoFe2O4 composites is significantly decreased compared to pure CoFe2O4 microspheres, the coercivity still maintains a high value of 626.1 Oe. As expected, the results demonstrate that as-fabricated MoS2/CoFe2O4 composites do have superior microwave absorption properties in comparison with CoFe2O4 and MoS2. It is found that the complex permittivity is enhanced with increasing filling ratio from 45 wt% to 60 wt%, which is helpful for obtaining a moderate permittivity value. When the filling ratio is 50 wt%, the MoS2/CoFe2O4 composites exhibit a minimum reflection loss (RLmin) of − 53.1 dB at 12.08 GHz when the thickness is 2.5 mm. An effective absorption bandwidth less than − 10 dB of 6.61 GHz from 11.28 to 17.89 GHz is achieved with a thin thickness of 2.2 mm, almost covering the whole Ku-band. The improvement in microwave absorption properties can be ascribed to the synergistic effect of the magnetic CoFe2O4 and dielectric MoS2. The impedance matching characteristic and interfacial polarization are significantly optimized by inserting CoFe2O4 spheres onto the surface of MoS2 nanosheets. Considering the excellent performance of as-fabricated MoS2/CoFe2O4 composites, it is believed that the MoS2-based composites can be applied as a promising candidate of highly effective microwave absorbers with strong absorption intensity and broad absorption frequency.

The effect of indium doping on structural and magnetic properties of Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe1-xInx)12O22 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) prepared by the solid state reaction method was investigated. The Rietveld refinement method was used to analyze the X-ray diffraction patterns. The magnetic transition temperatures associated with the proper-screw spin phase to the collinear ferrimagnetic spin phase transition can be efficiently modulated by varying indium content. The magnetic transition temperature increases to a maximum with indium content x = 0.04 and then decreases with x, suggesting the possibility that electrically controlled magnetization reversal can be can be effectively tailored by varying indium content. The saturation magnetization at room temperature was decreased as increasing indium content, which can be explained as the metal ions occupation. It is worthy to note that the coercivity of In-doped samples was decreased drastically compared that of undoped sample, which is probably resulted from the reduction in anisotropy field with substitution of In3+ for Fe3+. The In-doped hexaferrite Ba0.5Sr1.5Zn2(Fe1-xInx)12O22 may be potential candidates for application in magnetoelectric devices.

In this work, Metal Organic Frameworks (MOF)-derived the necklace-like carbon nanofibers (CNFs)@carbonaceous Co/CoO composite is synthesized by wet chemical and pyrolysis method. The CNFs are penetrated through the derived carbonaceous Co/CoO frameworks which retain the ZIF-67's sizes. Due to their unique structure and the well controlling of experimental parameters, the optimum reflection loss value of −53.1 dB at 6.56 GHz is obtained, and the corresponding bandwidth below −10 dB (90% absorption) is up to 13.52 GHz with the thickness range of 2.0–5.0 mm. Due to the low density of CNFs and MOF-derived carbon in the composite, the as prepared CNFs@carbonaceous Co/CoO composite can act as a new member of lightweight and high-efficient EM wave absorbents.

The effect of Mg substitution on structural, magnetic, and dielectric properties of Y-type hexaferrite Ba0.5Sr1.5Zn2-xMgxFe11AlO22 (x = 0, 0.4, 0.8, 1.2, 1.6, 2.0) prepared by the solid state reaction method was investigated. The X-ray diffraction patterns are analyzed by Rietveld refinement method and the hexagonal structure with R 3 − m was confirmed. The magnetic transition temperatures associated with the longitudinal conical to proper screw phase transition (T1) and proper screw to ferrimagnetic phase transition (T2) can be modulated by varying Mg content. For x ≤ 1.2 samples, the transition temperature T2 monotonically increases with increasing Mg substitution, suggesting the possibility that the helical spin order of Mg substituted Y-type hexaferrites is sustained up to higher temperatures than that of undoped samples. The saturation magnetization at room temperature increases to a maximum with Mg content x = 1.2 and then decreases with x. The variations of magnetic properties can be attributed to the difference in the preferential site for Zn and Mg and different distribution of Fe3+ ions over tetrahedral and octahedral sites. The results of magnetic field dependence of dielectric constant, i.e., magnetodielectric effect, at various temperatures imply that the doped samples show magnetically induced ferroelectricity up to 250 K. The intrinsic magnetodielectric effect is observed in all the samples. It is worthy to note that the magnetodielectric effect measured below 200 K increases with increasing Mg content, which is probably attributed to the variation of magnetic structures. The Mg-doped hexaferrites Ba0.5Sr1.5Zn2-xMgxFe11AlO22 may be potential candidates for application in magnetoelectric devices.

To design and synthesize materials for alkaline hydrogen evolution is favorable for industrial hydrogen cycle operation. In this study, we present a facile approach to synthesize free-standing ruthenium-beryllium (RuBe) nanosheets, which possess amorphous phase state and associated with holey structures due to the molten method. The two-dimensional RuBe nanosheets exhibit improved activity than pure Ru counterpart and comparable properties to commercial Pt toward hydrogen evolution reaction in both of alkaline and neutral electrolytes. Based on the experiments and density functional theory calculations, it is suggested that the adsorption and dissociation of water molecules on Ru-based catalyst are much enhanced with the assistance of Be modulation, which are essential for the improved hydrogen production capability under alkaline condition. This work broadens the Ru-based catalyst family and may provide new insights for electrocatalyst development.

Highly efficient, economical and environmentally friendly materials are important and remain a challenge in the renewable energy conversion and storage technologies. The oxygen evolution reaction has been envisaged on a two-dimensional graphyne (GY) nanosheet based on density functional theory framework. Local electronic/chemical environment on GY surface is significantly influenced and can be controlled by doping foreign atoms with different formats, which will contribute to its improved catalytic performance. Henceforth, free energy change diagrams, Raman spectra, natural bond orbital charge density, charge density difference, and other data have been calculated and discussed. It is suggested that boron doping at edge sites on GY is the ideal candidate for high OER activity, which is efficient as carbon-based electrocatalysts for water splitting and metal-air batteries.

Metal organic frameworks (MOFs) derived carbonaceous metal oxides and their composite have unique structures and superior properties, thus they have been widely used in various fields. In this study, we use Co based MOFs (ZIF-67) and GO as precursors, synthesize carbonaceous Co3O4/Co/RGO composite as high performance EM wave absorbing materials. The derived carbonaceous Co3O4/Co microframes retain the ZIF-67 nanoparticles’ structure are well dispersed onto the surface of RGO nanosheets. Due to their porous structures and the well controlling of electromagnetic parameters, the obtained composite exhibits a maximum absorption of −52.8 dB at 13.12 GHz, and the bandwidth corresponding to −10 dB (90% absorption) is up to 10.72 GHz (from frequency of 4.88–15.6 GHz) with a coating layer thickness range of 2.0–4.0 mm. Therefore, the synthesized MOF-derived carbonaceous Co3O4/Co/RGO composite is a new promising candidate as highly useful microwave absorbers.

The microstructure and magnetic properties of Mg-doped Ba0.5Sr1.5Zn2Fe12O22 hexaferrites synthesized by the solid state method are investigated. All the undoped and doped samples show a sharp screw proper spin phase to collinear ferrimagnetic spin phase transition above room temperature, and transition temperature increases distinctly with Mg doping. It is noteworthy that all the samples exhibit another magnetic phase transition at a lower temperature T1, which is associated with the longitudinal conical to the proper screw phase transition. The transition temperature T1 can be modulated by varying Mg content, indicating that the longitudinal conical spin phase is stabilized by the Mg-substitution. The saturation magnetization at room temperature increases to a maximum with Mg content x = 0.8 and then decreases with x. The variations of magnetic properties can be ascribed to the difference in the preferential site for Zn and Mg and different distribution of Fe3+ ions over tetrahedral and octahedral sites. It is worth noting that the range for the intermediate-III phase increases significantly as x increases to 2.0, suggesting that Mg-doped samples may be display field-induced ferroelectric order at temperature close to RT and in wide magnetic-field regions. The room-temperature M-H curves at lower applied field indicate that magnetic-field-induced ferroelectric phase can be stabilized at zero magnetic field by the substitution by Mg2+ for Zn2+. The Mg-doped hexaferrites Ba0.5Sr1.5Zn2Fe12O22 may be potential candidates for applying in magnetoelectric devices.

Transparent and conductive Ta doped BaSnO 3 (BaSn 1−x Ta x O 3 , BSTO) films with x = 0–0.15 were epitaxially grown on MgO single crystalline substrates by a pulsed laser deposition method. The effects of Ta ions incorporation on the microstructure, electrical and optical properties of BSTO films were investigated. X-ray diffraction measurements indicate that the out-of-plane lattice parameters increase gradually with Ta concentration increasing, and the films are relaxed due to the large lattice mismatch between the films and substrate. Atomic force microscopy images reveal that all the films have smooth surface and low roughness. X-ray photoelectron spectra of BSTO films confirm that the Ta ions are presented in the +5 state. The lowest room-temperature resistivity and the highest carrier concentration and Hall mobility were observed in BSTO film at x = 0.07, with the values of 2.525 mΩcm, 5.024 × 10 20 cm −3 , and 4.921 cm 2 /Vs, respectively. Temperature dependent resistivity behavior shows that the BSTO films with low doping content exhibit metal-semiconductor transition at low temperature. The optical transmittances of all BSTO films are more than 80% in the visible region. The optical band gaps were found to increase from 3.52 to 4.23 eV with the increase of Ta doping content and can be attributed to the Burstein-Moss effect. Thus, the superior electrical and optical properties of Ta doped BaSnO 3 films are comparable to that of La and Sb doped BaSnO 3 films, and have potential applications in the optoelectronic devices.

Multiferroic Y-type Ba2Mg2Fe12O22 (BMFO) hexaferrite, spinel Ni0.5Zn0.5Fe2O4 (NZFO) ferrite, and multi-walled carbon nanotubes (MWCNTs) ternary composites have been successfully fabricated via one-step sol-gel method followed solvothermal method. The electron microscopy analysis exhibits that platelet-like BMFO and quasi-spherical NZFO grains are surrounded by dispersed MWCNTs. The magnetic and microwave absorption (MA) performances are hugely associated with the mass ratio of BMFO to NZFO phase. The saturation magnetization of composites increases from 24.2 to 69.0 emu/g, while permittivity declines apparently with increasing NZFO content. It is easy to infer that the addition of NZFO phase may be beneficial to balance the relative permittivity and permeability of BMFO@NZFO/MWCNTs, which can endow the strong reflection loss of the composites. When the mass ratio of BMFO to NZFO is 3:1, the absorber shows the minimum reflection loss of −36.1 dB at 14.3 GHz with a relatively thin thickness of 1.8 mm, and effective absorption bandwidth (less than −10 dB) of 4.1 GHz. When the mass ratio is reduced to 1:3, the minimum reflection loss reaches to −40.8 dB at 10.6 GHz with an absorber thickness of 2.5 mm, and the effective absorption bandwidth is achieved in the frequency range from 8.0 to 11.9 GHz which covers almost the whole X band (8.0–12 GHz). For the two composites mentioned above, the effective absorption bandwidth covers almost the entire frequency range by changing the absorber thickness from 1 mm to 5 mm. Very interestingly, the effective absorption band shifts to the low frequency by adding NZFO, attributing to adequate exchange-coupling interaction between BMFO and NZFO phases. These mentioned results demonstrate that composites consisting of multiferroic Y-type hexaferrite, spinel ferrite and carbon material have a potential application in high-performance MA materials integrating vigorous absorption intensity, broad absorption bandwidth and thin thickness.

Lightweight, inexpensiveness, easy synthesis, associated with high and broadband absorption are the intensive pursuit for advanced microwave absorbents. Herein, we employ a facile preparation to create holey structures on the wasted biomass-derived carbon materials by air-calcination. All of the carbon absorbents derived from wasted corn cobs, bagasse and grapefruit peels exhibit controlled holey structures on their surfaces, demonstrating the universality of this strategy. The obtained metal-free products are fabricated from bare wasted biomass, without any additional reagents addition. Benefiting from the holey structure generation, more incident microwaves can be consumed due to the increased surface areas and polarization centers for the microwave radiation. The performance measurements suggest the achieved sample could reach a minimum reflection loss value of −47.0 dB at 14.1 GHz and an effective absorption bandwidth (lower than −10 dB) of 5.5 GHz. It is anticipated that this facile holey generation method can be extended to more wasted biomass-derived carbon materials for more sustainable applications.

Bio-derived dielectrics have drawn extensive attention for microwave absorption and shielding because of renewability and environmental friendliness. In this work, foam-like bio-carbon has been obtained from wheat straw waste and its microwave absorption performance has been studied. By controlling the precursor ratio of KOH, the optimized morphology of bio-carbon has been realized. The 3D carbon foam obtained at 600 °C with KOH and biomass ratio 1:1 (AC-600 (1:1), presents decent microwave reflection loss. Especially, with a low absorber ratio (10 wt%), the effective absorption bandwidth (RL

Here, we synthesized LaNiO3 microspheres by a simple hydrothermal synthesis and subsequent annealing process. The LaNiO3 microspheres are characterized by TG-DSC, XRD, FESEM, TEM and VAN. Noticeably, owing to the effective synergism between significant dielectric loss and optimum impedance match, LaNiO3 microspheres exhibit significantly remarkable attenuation capability and wide-band respond. Therefore, the possible mechanism of microwave absorption enhancement is carefully investigated. A minimum reflection loss intensity −30.6 dB of LaNiO3 microspheres can be achieved and a broad effective absorbing bandwidth (reflection loss reaches −10.0 dB) of 4.72 GHz (8.16–12.88 GHz) at the thickness of 2.0 mm. Furthermore, the overall effective bandwidth is obtained up to 14.5 GHz from 3.5 GHz to 18 GHz, covering more than 90% of the measured frequency range. It is expected that the LaNiO3 microspheres could be used to design efficient microwave absorption materials.

Reduced graphene oxide (RGO) nanosheets normally possess large specific surface area, good electrical conductivity, and low density, but their unsatisfactory intrinsic complex permittivity and poor impedance matching severely hinder the further application in microwave adsorption. In this work, borophene nanosheets (BNS), the lightest 2D material, are proposed as an efficient activator to improve the microwave absorbing performance on RGO. BNS are assembled and immobilized on RGO surface through the interfacial covalent interaction, to construct a new metal-free 2D hybrid absorbent. These incorporated BNS serves as the joining site and channel in the framework to facilitate electrons hopping and migration between RGO layers. As a result, conductive loss mechanism is well enhanced, which is the major contribution to its dielectric property, conferring high impedance matching on the absorbent. As expected, the as-obtained 2D metal-free hybrid demonstrates microwave absorbing parameters that approach those of the most active absorbents, with the minimum reflection loss reaching −53.3 dB and the broadest effective absorption bandwidth of 6.16 GHz, at a low filler loading of 3 wt%.

Over a long period of time, single iron oxide (Fe2O3) or cobalt oxide (Co2O3) has been extensively studied for magnetic absorbing materials. Recently, some nanoscale compounds composed of two ferrites have been reported for better electromagnetic absorbing properties because of collectively corporation. However, there are few reports about other magnetic absorbing materials. In addition, morphology control for better absorbing performance remains challenging. Here, the monodispersed, uniform rod-shaped FeCO3/CoCO3 microparticles are successfully synthesized by a facile one-step solvothermal method for the first time. The experimental results show that the reflection loss (RL) value of the paraffin composites with thickness of 2.0 mm is less than −10 dB in the frequency range of 6.72–15.92 GHz and the minimum RL value of −31.86 dB at 12.88 GHz is obtained, which demonstrates that the as-prepared FeCO3/CoCO3 microparticles have excellent magnetic and microwave absorbing properties.

Many nanomaterials have been widely reported for removal of toxic inorganic metal ions. However, some nanoscale adsorbents are subject to serious aggregation. For example, it is very difficult to directly synthesize the monodispersed Fe(OH) 3 nanomaterials. Here, through using the monodispersed hierarchical γ-Al 2 O 3 nanoflowers as adsorbent supports, the Fe(OH) 3 colloid nanoparticles have been well deposited onto the surfaces of the hierarchical γ-Al 2 O 3 nanostructures to form γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures via an electrostatic attraction without forming large aggregates. The γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures have high specific surface areas and large pore volumes, which are used as adsorbents to remove anion species of As(V) and Cr(VI) from aqueous solution. The maximum capacities of the monodispersed γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures for As(V) and Cr(VI) are determined at 61.99 mg g −1 and 24.13 mg g −1 , respectively, which are higher than those of the other metal oxide nanostructures reported. In addition, the adsorption rates of As(V) and Cr(VI) onto the monodispersed γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures are rather fast. The γ-Al 2 O 3 /Fe(OH) 3 hierarchical micro/nanoflower structures show high adsorption capacity for removing anion species of As(V) and Cr(VI), demonstrating a promising potential in environmental remediation.

In this work, Bi 2 MoO 6 /multi-walled carbon nanotube (MWCNT) hybrid was prepared through a facile hydrothermal process. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS) and N 2 adsorption–desorption isotherms were used to investigate the morphology, crystal structure, optical properties and specific surface area of Bi 2 MoO 6 /MWCNT nanocomposite. It was shown that Bi 2 MoO 6 nanoparticles were well-deposited on the outer surface of Bi 2 MoO 6 /MWCNT. Photocatalytic properties of as-prepared photocatalysts were investigated under 410 nm LED light irradiation for photodegradation of methylene blue. The corresponding the apparent pseudo-first-order rate constant k app of Bi 2 MoO 6 /MWCNT is 0.087 min −1 , which is 4.4 times and 17.4 times more than that of pure Bi 2 MoO 6 and P25 photocatalyst, respectively. Moreover, photodegradation mechanism of Bi 2 MoO 6 /MWCNT was provided.

The band engineering of visible-light-driven photocatalysts is a promising route for harnessing of effective solar energy to perform high chemical reactions and to treat environmental pollution. In this study, two narrow band gap semiconductor nanomaterials, graphitic carbon nitride (g-C3N4) and Bi2MoO6, were selected and coupled to form series of g-C3N4/Bi2MoO6 photocatalysts. Their structure, light absorption wavelength range, charge transport properties and energy level were investigated. Through perfect manipulation of their composition, enhanced photocatalytic activity of the Z-scheme g-C3N4/Bi2MoO6 photocatalysts with efficient reduction of recombination of photogenerated electrons and holes was achieved. The optimized Z-scheme g-C3N4/Bi2MoO6 photocatalysts with 25 wt%g-C3N4 showed apparent pseudo-first-order rate constant kapp as high as 0.0688 min−1, which was 4.8 times and 8.2 times higher than that of g-C3N4 and Bi2MoO6 photocatalyst, respectively.

Carbonyls iron powders (CIPs)/Fe3O4 composites have been prepared by a simple hydrothermal method through controlling the pH value of the reaction system. The obtained products were characterized by X-ray diffraction (XRD), Raman spectrum, scanning electron microscopy (SEM), superconducting quantum interference device magnetometer (SQUID), thermogravimetry–differential thermal analysis (TG–DTA), etc. The microwave absorption properties of the CIP/Fe3O4 composites were measured by vector network analysis (VNA). A wide region of microwave absorption was achieved due to the high permeability of CIP/Fe3O4 composites (pH = 13). When the matching thickness is 2 mm, the reflection loss of the sample exceeding −10 dB was obtained at the frequency range of 8.7–15.0 GHz, with an optimal reflection loss of about −38.1 dB at 11.5 GHz. A possible mechanism of the improved microwave absorption properties of the composites was discussed.

The granular composites of (1−x)La0.7Sr0.3MnO3/xSrFe12O19 [(1−x)LSMO/xSFO] were prepared. The magnetic, electrical, and magnetoresistive properties of the composites were investigated systematically. Two magnetic transitions originating from LSMO and SFO are observed for x=0.05, 0.10, and 0.20. The addition of hard-magnetic SFO ferrite leads to the increased substantially resistivity of the composites and the shift of insulating-metallic transition temperature TIM correlated with LSMO. Enhanced low-field magnetoresistance (LFMR) in the composites can be mainly attributed to the enhanced spin disorder and spin-dependent tunneling at LSMO grain boundaries induced by the interaction between LSMO and SFO ferrite. The transport mechanisms in detail are analyzed in LSMO/SFO composite system.

On basis of the redox reaction between MnO 4 − and Mn 2+ , a facile hydrothermal method combined with the adjustment of pH value in the reaction system has been employed to synthesize single-crystal γ-MnOOH nanorods, and square-like Mn 3 O 4 nanoparticles. Additionally, single-crystalline β-MnO 2 and Mn 2 O 3 nanorods can be obtained after subsequent calcinations of the as-prepared γ-MnOOH nanostructures at 300 °C and 600 °C, respectively. Furthermore, electrochemical property of as-obtained β-MnO 2 is also studied.

The precursor manganese carbonate was synthesized via a hydrothermal reduction route. After decomposition of the above precursor, α-Mn2O3 and MnO could be successfully obtained under the atmosphere of air and argon, respectively. The morphology of α-Mn2O3 and MnO was directly determined by that of precursor MnCO3. It is found that the pH is the vital factor affecting the morphology of precursor MnCO3. The products were characterized by X-ray diffraction and scanning electron microscopy.

A low temperature surfactant-assisted hydrothermal synthesis route has been successfully developed for the preparation of high quality chalcostibite (CuSbS2) nanorods. The surfactant concentration is a key factor influencing the quality (size, shape) of the final products. A possible mechanism is proposed for the formation of chalcostibite nanorods. Several techniques including XRD, SEM, TEM and XPS were used to characterize the as-prepared chalcostibite nanorods.

Semiconducting Tin(II) monosulfide nanowires, nanorods and nanoparticles were successfully selectively prepared using SnCl 2 ·2H 2 O and thiourea (Tu) as the raw materials by appropriately choosing different alkaline solution as reaction media. The SnS nanowires are uniform with diameters 30–70 nm and lengths 3–10 μm, the nanorods are about several micrometers long with average width of 60–200 nm and the nanoparticles have an even diameter of about 5–10 nm. Compared to the previous reports, the present method is relatively simple, without using complex apparatus, and manipulated conveniently, which may be favorable for industrial application in the future.

La 0.6 Sr 0.4 MnO 3 (LSMO) particles were prepared by the sol–gel method with and without an external magnetic field (H ext = 4 kOe). Structural and magnetic properties were investigated. X-ray powder diffraction results show that both samples are single-phase. Field-emission scanning electronic microscopy shows that the mean particle size of LSMO particles synthesized under H ext = 4 kOe is larger than that of the sample without an external magnetic field. The enhanced magnetic properties are attributed to the magnetic-field effect.

Cerium (IV) oxide films were deposited on silicon substrates by nebulization of a 0.01 M solution of cerium acetylacetonate in a 50% ethanol–water mixture followed by pyrolysis in flowing air. The films were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. On the basis of the experimental evidence, the technical conditions were selected. Appropriate control of the ratio of pulse time to interval time was found to be necessary for obtaining high quality and greater crystallite size cerium (IV) oxide thin films.