Nowadays, electromagnetic interference receives great attention for wireless communication and charging, electronic device, and modern weapons. Materials and the various novelty structures are required and designed to absorb the emitted electromagnetic wave energy and to minimize reflection of the electromagnetic wave in certain direction. Development of graphene-based electromagnetic absorption materials are reviewed, consisting of composition materials with other carbon materials, nano-metal materials, ferrite materials, polymer materials, and non-metallic materials. The electromagnetic absorption mechanisms is briefly described and the influences of microstructure, fraction and loss mechanism on the absorption properties are discussed. The future of graphene-based electromagnetic absorption materials is also prospected.

Dendritic fibrous nano-silica (DFNS), especially the sphere-shaped with three-dimensional (3D) center- radial channels and hierarchical pores, possess higher specific surface areas, larger pore volumes, higher pore permeability, more accessible internal spaces, etc. Guest substances (e.g., ultrasmall nanoparticles) can be loaded onto and transported in the radial nanochannels, or can even react with the chemically active sites in these nanochannels. As a result, DFNS can serve as promising platforms to construct novel nanocatalysts, adsorbent materials, and delivery systems for genes, proteins or drugs. A majority of investigations about DFNS have demonstrated that silica nanospheres with this special topography have inherent superiorities over traditional mesoporous MCM-41 or SBA-15, and can be perfect alternatives. Nevertheless, reviews on DFNS are limited, and there still exist plenty of issues that need to be probed into. Therefore, this comprehensive review provides a critical survey on DFNS’ structural characteristics, commonly used structural models, novel structures, real-time applications, etc. We sincerely expect that this paper could give material scientists and chemists certain inspiration to accelerate DFNS family’s booming evolution.

Ni doping woodceramics were prepared from papermaking black liquor lignin and NiCl₂·6H₂O, which sintered at 1200℃ and then activated with KOH. The Ni doping activated graphite woodceramics presents 3-D net structure with foam formation. X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscope, specific surface area tester, and electrochemical workstation were employed to characterize the samples. The results show that Ni constructs the framework of woodceramics, and catalyzes graphitization of amorphous carbon. The sample displays obvious graphitization tendency, and graphene lamellar structure is found. The lattice spacing is close to the lattice parameter of ideal graphite. Meanwhile, activating treatment can effectively form hierarchical porous and increase the quantity of micropores and ultramicropore. The pore diameter mainly concentrats at 3.60 nm, and the specific surface area increases from 359 m²·g^-1 to 856 m²·g^-1, as the sample activated at 800℃ for 3 h. Additionally, activation improves the electrochemical performance of Ni doping woodceramics, whose specific capacitance is 153.8 F·g^-1 at 20 mV·s^-1 scanning rate, 2.2 times higher than that of non-activated sample.

As one of the most widely used oxide in many fields, Y₃Al₅O₁₂(YAG: Yttrium Aluminum Garnet) has attracted extensive attention. However, due to its high melting point and complex mechanism for phase selection, accurate knowledge of thermo-physical properties for YAG melt, is much desired. Using an advanced aerodynamic levitation laser-melting technique, here the viscosity, surface tension and density were carefully evaluated on both thermodynamically stable, and metastable supercooled YAG melts in the temperature scope from 1750 K to 2650 K. The results indicate that density of YAG melts has a higher sensitivity than that of Al₂O₃ melts upon temperature change; and YAG melts have one time higher average line thermal expansion coefficient compared to the Al₂O₃ melts. Al₂O₃ melts’ surface tension is almost constant on temperature in the wide temperature scope, while YAG melts have a distinct decrease in surface tension following temperature increase. As to the viscosity-temperature relation, in the supercooled scope, YAG melts have a more obvious rise in viscosity upon cooling.

Nano-structured tungsten oxide (WO₃) thin films were deposited at room temperature by glancing angle reactive magnetron sputtering and then annealed at 450℃ in air. The films were characterized by field-emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). The WO₃ thin film deposited by DC magnetron sputtering at 80° glancing angle exhibited oblique nano-column structure, while deposited by pulsed DC magnetron sputtering at the same angle exhibits nano-pore structure. After annealing at 450℃ for 3 h, the oblique nanocolums are conjunct with each other but the nano-pore structured remains with bigger pore size. XRD analysis reveals that WO₃ thin films deposited at room temperature demonstrate amorphous structure. The amorphous structure will transfers to monoclinic phase after annealing at 450℃ for 1 h. Transmittance difference between colorization and bleaching of nano-structured WO₃ thin film reaches 60% at wavelength of 600 nm. Electrochromic properties of nano-structured WO₃ thin films are highly reversible.

Effects of different heat-treatment process on the crystallization, phase composition and content, and microstructure of 19MgO-23Al₂O₃-53SiO₂-4TiO₂-2.5B₂O₃ (wt%, M-A-S-T-B) were studied by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The influence of different nucleation and crystallization time on the microwave dielectric properties were discussed as well. The results showed that, based on the controlled crystallization mechanism of glass, MgSiO₃ phase was precipitated adequately for M-A-S-T-B samples heat-treated at 850℃/2 h + 950℃/2 h, and also, the α-cordierite, xMgO-yAl₂O₃-zSiO₂ and α-SiO₂ phases could be precipitated from matrix phase. Additionally, with the increase of nucleation time, types of crystalline and phase content were found no discernible changes in the M-A-S-T-B glass-ceramics. While crystallization time increased to 20 h, the crystallized volume fraction of the glass increased, leading to the improvement of the quality factor (Q×f) and the obvious precipitation of granular grains. However, the dielectric loss slightly increased and the relative density of specimens decreased with further increase of crystallization time (30 h). Wherein, the M-A-S-T-B glass-ceramic sample heat-treated at 850℃/2 h + 950℃/20 h exhibited the excellent microwave dielectric properties of ε_r ~ 3.85, Q×f ~ 12740 GHz (at 13.973 GHz) and τ_f ~-5.37×10^-6/℃.

Pd-doped organic-inorganic hybrid SiO₂ (POS) sols were synthesized by using 1,2-bis(triethoxysilyl) ethane (BTESE) and palladium chloride as precursors. POS membranes were fabricated via dip-coating process followed by calcination in the water vapor environment. The microstructure of POS powders was characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), N₂ adsorption-desorption, and transmission electron microscope (TEM). Effect of the molar ratio of Pd to Si (n (Pd/Si)=0.1, 0.5 and 1) on separation performance and hydrothermal stability of POS membranes was investigated. Results showed that with the increase of Pd doping amount, H₂ permeance of POS membranes increased while the permselectivity of H₂/CO₂ decreased. After exposing to 100 kPa steam atmosphere for 180 h, H₂ permeance and H₂/CO₂ permselectivity of the POS membrane prepared with n (Pd/Si) of 1 reached 1.62×10^-7 mol·m^-2·s^-1·Pa^-1 and 13.6, respectively. This result indicated that as-prepared POS membrane exhibited good H₂ permeance, H₂/CO₂ permselectivity and hydrothermal stability.

VO₂(B)/ZnO nanorods hierarchical heterogeneous composite was synthesized by solution growth method on VO₂(B) nanorods surface. Effects of ZnO seeds’ solution concentration on microstructure and NH₃ gas sensing properties of composite structures were investigated. X-ray diffractometer and scanning electron microscopy were used to characterize the crystal structure and surface morphology of the samples. NH₃ gas sensing properties of the composite was measured by the gas testing system at different temperatures and gas concentrations. The results show that ZnO grows on VO₂(B) surface and changes its shape from nanoparticle to nanorod as the ZnO seeds’ solution concentration increasing from 0.002 mol/L to 0.03 mol/L. ZnO nanorods radially grows on the VO₂(B) nanorod surface and branch-shaped hierarchical heterogeneous VO₂(B)/ZnO composite structures are formed when the solution concentration is 0.01 mol/L. The composite exhibits high gas response and outstanding selectivity at room temperature. The response value reaches 5.6 while the response time is reduced to 2 s at room temperature. This excellent NH₃ gas sensing performance is related to the highly dense VO₂(B)/ZnO hetero-junction and hierarchical structure. The present results may provide more information for design and fabrication of low power and high sensitive NH₃ gas sensors at room temperature.

(1-x)(Bi_0.5Na_0.5)_0.935Ba_0.065TiO₃-xBiScO₃ (BNBT-xBS) lead-free ceramics were fabricated by conventional ceramic sintering process and modified by BiScO₃. Effects of BiScO₃ content on microstructure, energy storage, field-induced strain and dielectric properties of BNBT-xBS ceramics were investigated. The results indicated that the structure of BNBT-xBS ceramics without impurity phase transferred from the co-existence phase of rhombohedral and tetragonal phase to pseudo-cubic phase. Average grain size of BNBT-xBS ceramics grew slightly with increment of doping content. The long-range ferroelectric order of BNBT-xBS ceramics was destroyed by BiScO₃, which resulted in weak polarization. Meanwhile, the phase transition of BNBT-xBS ceramics was observed from a typical ferroelectric phase to relaxor phase. BiScO₃ dopants improved energy storage and strain performance of ceramics as well, whose maximum energy storage density and high strain were 0.46 J/cm³ and 0.25% at 70 kV/cm. The dielectric constant decreased with doping content increasing. Relaxor ferroelectric characteristics were also verified by temperature-dependence dielectric spectra. The resistance of BNBT-xBS ceramics illustrated a negative temperature coefficient and excellent electrical insulativity below 450℃.

Bottom-up assembly of nanoparticles into new materials with sub-wavelength features has become an important means to manipulate and utilize light. Here, we report a novel nano-assembly technology, named silicon oil two-step dehydration method. This method utilizes the rheological and confinement effects of the oil-water interface and enables the assembly of 15 nm titanium dioxide (TiO₂) nanoparticles into macroscopic hemispherical optical lenses with high refractive index and high transparency. The TiO₂ lens can be large-scale produced with this method. Moreover, the assembly process and mechanism are analyzed in details. In addition, this method can also achieve uniform composites of TiO₂ nanoparticles with other nanomaterials, such as gold (Au) nanoparticles, Au nanorods, Au nanocubes or graphene oxide, enabling the preparation of TiO₂/Au or TiO₂/graphene oxide composite devices. Among them, after the recombination of TiO₂ nanoparticles, the surface plasmon absorption peak of Au nanoparticles, Au nanorods or Au nanocubes have a significant red shift, indicating that this assembly method provides an effective way for the preparation of functional composite optoelectronic devices in the future.

CdS/TiO₂ heterojunction films have attracted much attention in the field of photocatalysis due to their excellent photocatalytic performance under visible light irradiation. However, the CdS/TiO₂ films prepared by the conventional methods may exhibit loose interface, leading to poor transport of photogenerated carriers in the interface. In this study, CdS/TiO₂ heterojunction films were successfully prepared by in-situ transformation (TiO₂→CdTiO₃→CdS). Morphologies and structures of as-prepared films were characterized by XRD, SEM and TEM. Results show that CdS formed on the surface of TiO₂ nanoparticle, and the interface of CdS/TiO₂ heterojunction was compact. Their photoelectrochemical (PEC) performance was investigated by electrochemical working station．Results indicate that the CdS/TiO₂ films prepared by in-situ method, whose photocurrent density was as high as 9.8 mA∙cm^-2 at 0.4 V (vs. RHE), present higher PEC activity than those prepared by successive ionic layer adsorption and reaction (SILAR). The electrochemical impedance spectroscopy (EIS) results show that the in-situ synthesized CdS/TiO₂ films own lower charge transfer resistance, which reveals that the in-situ formed compact interface can reduce the charge transfer resistance in the CdS/TiO₂ interface, restrict the recombination of photo-induced carriers, and further enhance the PEC performance.

To improve the rate performance of LiFePO₄ cathode material, LiFePO₄ nanoplates were synthesized via one-step glycol-based solvothermal process. Additionally, carbon was employed to coat LiFePO₄ with glucose served as carbon source. The morphologies and electrochemical properties of the as-prepared materials were characterized by XRD, BET, SEM, TEM, cyclic voltammetry, etc. Results showed that LiFePO₄ nanoplates had the size of approximately 150 nm×100 nm×60 nm, displaying a short b-axis. The rate performance of LiFePO₄ nanoplates was enhanced with the increment of carbon content, and the sample containing 6.4wt% carbon (LF0.2) exhibited the most outstanding electrochemical performance, which delivered discharge capacities of 157.3 mAh/g and 132.6 mAh/g at 0.2C and 10C rates, respectively. Meanwhile, excellent cycling stability of LF0.2, 80.2% capacity retention after 500 cycles at 5C rate, was observed.

Graphene/hydroxyapatite (rGO/HAp) composite bioceramics were fabricated by plasma activated sintering using hydroxyapatite (HAp) as matrix and graphene (rGO) as reinforced phase. The effects of rGO addition on phase structure, bioactivity and fracture toughness of HAp ceramics matrix were systematically investigated. The results indicate that the incorporation of rGO is beneficial to promoting the bioactivity of HAp ceramics. Meanwhile, hardness and fracture toughness of composite bioceramics initially increase and then decrease significantly with rGO concentration increasing. The hardness and fracture toughness of the specimen with rGO loading of 2wt% reach 6.97 GPa and 0.84 MPa•m^1/2, which display ~11.5% and ~37.3% improvements as compared to pure HAp ceramics, respectively. It is demonstrated that the pull-out effect of rGO is the major reason for enhancing the mechanical properties of composite ceramics.

Micro/meso-porous SiOC ceramics with high surface area and narrow pore size distribution were prepared by the low temperature phase separation method (namely water vapor assisted pyrolysis) followed by etching in hydrofluoric acid (HF) solution. The cross-linked body was made from hydrogen-containing polysiloxane (PHMS), tetramethyl-tetravinylcycletetrasiloxane (D₄^vi) and Pt-complex by thermal cross-linking. Phase compositions, chemical bonds, microstructures, and specific surface area of the prepared SiOC ceramic were investigated by XRD, FT-IR, SEM, and BET, etc. Water vapor can promote the precursor to produce Si-O-Si bonds, SiO₂-rich clusters, and SiO₂ nanocrystals in SiOC ceramics. All of these species act as pore-forming substrate and can be etched away by HF. Water vapor injection and pyrolysis temperature have important effects on phase compositions, microstructures and specific surface area of SiOC porous ceramics, which have a maximum specific surface area of 1845.5 m²/g and pore size distribution of 2.0-10 nm at pyrolysis temperature of 1300℃.

Avoiding the use of templates and employing natural minerals as raw materials could promote the cost-efficient preparation of mesoporous materials. This work demonstrated a template-free route to process natural halloysite into mesoporous silica with high specific surface area (SSA) up to 767 m²/g and pore size of about 5 nm. The halloysite was successively calcined, alkali-treated and acid-treated. The transformation of calcined halloysite into crystalline sodium aluminosilicate (zeolite LTA) by longtime alkali-treating, was found to be the key for obtaining high-SSA mesoporous silica in the final acid treatment. The optimized mesoporous silica showed a monolayer adsorption capacity as high as 741 mg/g for methylene blue, suggesting its great potential in adsorption applications.