As one of microwave absorbing materials, SiC nanowires have a good microwave absorbing property, a wide microwave absorbing bandwidth and a low density. However, the poor impedance matching condition and low conductivity of SiC affect the improvement of its microwave absorbing property. To adjust the electronic structure of SiC and improve its electromagnetic properties, La³⁺ doped SiC nanowires were synthesized via carbothermal reduction at 1 600 ℃ with silicon powder, activated carbon and La₂O₃ powder as raw materials. The results show that doping La³⁺ can increase the aspect ratio and stacking fault density of SiC nanowires, and enhance their ability to form three-dimensional network structure and interface polarization, and improve their dielectric properties. At 2-18 GHz, the real part of permittivity increases from 3.08-13.48 (x = 0) to 3.33-19.75 (x = 1.0%), and the imaginary part of permittivity increases from 3.45-6.98 (x = 0) to 5.03-11.56 (x = 1.0%). Also, La³⁺ doping improves the conductivity of SiC nanowires and enhances its conductivity loss. SiC nanowires doped with 1.0% La³⁺ achieve a minimum reflection loss (R_L) of -31.29 dB with the thickness of 2.0 mm and the effective absorption bandwidth with R_L<-10 dB of 7.18 GHz due to the simultaneous enhancement of interface polarization and conductivity loss of SiC nanowires. The electronic structures of SiC nanowires and La³+doped SiC nanowires were analyzed via the first-principle calculations. The results show that the band gap of SiC nanowires decreases after La³⁺ doping, verifying the enhancement of their conductivity. La³⁺ doping can increase the stacking fault density of SiC nanowires and solve a problem that the stacking fault density decreases. The results of this study can provide an idea for the synthesis of SiC nanowires with a high electromagnetic absorbing capability.

Metal-supported solid oxide fuel cells have promising applications. However, there is no the corresponding cost-effective preparation technology. Yttria stabilized zirconia (YSZ) electrolyte of solid oxide fuel cell was fabricated on a meatal substrate via high-efficiency and low-cost atmospheric plasma spraying (APS). The relationship between depositional particle morphology and coating structure under heating matrix conditions was investigated. The mechanical properties of electrolyte and cell out performance were evaluated. The results indicate that YSZ deposition particles on the heated substrate are fully spread. However, some microcracks appear in the splats, leading to some vertical cracks and interlamellar unbonded-interfaces inside the coating, the porosity is 7.16%, and nanoindentation hardness and elastic modulus of YSZ electrolyte are (13±1.04) GPa and (188.5±2.59) GPa, respectively. The maximum open voltage of cell with YSZ electrolyte deposited by APS is 0.97 V, thus improving the density. Nevertheless, the cell out performance is quite considerable with a peak power density of 850 mW/cm² at 900 ℃. After the optimization of equipment iteration or combined with the post-treatment process, APS can be used to obtain alarge-scale and low-cost preparation of dense YSZ electrolytes.

Cu₂ZnSnS₄ has good photocatalytic application prospects due to its high absorption coefficient in a visible light range and high carrier mobility, but the limited photocatalytic activity and catalytic stability restricts its practical applications. Cu₂ZnSnS₄ nanomaterial was prepared by a hydrothermal method with zinc chloride, tin chloride, copper chloride and thiourea as precursors, and PEG400 and OP10 as surfactants. The microstructure of the as-prepared Cu₂ZnSnS₄ nanomaterial was characterized and the influence of surfactant on the optical band gap and the photocatalytic degradation performance of the samples was determined by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy, respectively. The results show that three kinds of Cu₂ZnSnS₄ materials prepared all have a kesterite micro-phase, and the addition of PEG400 and OP10 into the precursor results in the variation of the microstructure, stoichiometric ratio and optical band gap of the materials, consequently determining their photocatalytic properties. After methylene blue degradation for 50 min, Cu₂ZnSnS₄ nano-powder synthesized with PEG400 has an optimum photocatalytic degradation rate (i.e., 95.7%). It is indicated that the photocatalytic activity and stability of Cu₂ZnSnS₄ nanomaterials can be improved by reducing the optical bandgap and enhancing the crystallinity, thus paving a promising approach to improve its photocatalytic performance.

The existing NO_x post-treatment techniques of diesel vehicle exhaust have a poor performance during the cold start, passive NO_x adsorbent (PNA) is thus proposed. In this paper, Pd/ZSM-5 PNA was obtained by loading 1% Pd onto ZSM-5 zeolite in Si/Al ratio of 11.5 via incipient wetness impregnation and ion exchange, respectively. The effect of reaction atmosphere (with or without O₂ and H₂O) on the adsorbed-released NO_x performance of PNA with two Pd loading methods was investigated. The mechanism of the factors affecting the structure properties, Pd species state and acid properties of Pd/ZSM-5 was analyzed by X-ray diffraction, N₂ adsorption-desorption isotherm, transmission tlectron microscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy and NH₃-temperature programmed desorption, respectively. The O₂ effect in the pretreatment atmosphere was further evaluated. The results show that there are more NO active adsorption sites with O₂ in pretreatment and reaction atmosphere during incipient wetness impregnation, thus improving the NO adsorption capacity of Pd/ZSM-5. In addition, O₂ promotes the release of NO_x at a lower temperature (~200 ℃), and an incipient wetness impregnation method reduces the release temperature to 430 ℃, which is conducive to the material regeneration. H₂O inhibits NO adsorption, but promotes NO_x release capacity at a higher temperature. This work can provide a reference for the design of high-performance Pd/zeolites. High adsorption-release capacity is the important prerequisite for the development of high-performance PNA.

Mordenite is highly active for the carbonylation of dimethyl ether reaction, and the regulation of its acid sites is an effective way to improve its catalytic performance. In this paper, a series of mordenite was subjected to the post-treatment of oxalic acid solution. The changes in the structure and acid sites were characterized by X-ray diffraction, N₂ adsorption-desorption, scanning electron microscopy, NH₃-temperature-programmed desorption and Py-infrared spectroscopy, respectively. The results show that the overall relative crystallinity and crystal phase of mordenite remain stable. However, the acid wash post-treatment can effectively remove parts of the acid sites through "etching" or complexation, especially those located in the twelve-membered ring channels. Meanwhile, it can create a certain amount of mesopores inside the particles, leading to an increase of the mesopore volume. The catalytic test results of dimethyl ether carbonylation reaction indicate that the sample treated with a suitable concentration of oxalic acid solution can effectively improve the dimethyl ether carbonylation activity. The dimethyl ether conversion significantly increases, despite the methyl acetate selectivity only slightly decreases. However, parts of the active sites responsible for the carbonylation reaction are removed when treated with high-concentration oxalic acid solution, resulting in a decrease in the catalytic activity. This research provides a simple and effective method for the regulation of the acid sites in mordenite and the improvement of its dimethyl ether carbonylation activity.

The osteogenic activity and mechanical properties of the bone repair scaffold are important for its clinical application. Mg-M/HT porous composite scaffold was prepared with hardystonite (Ca₂ZnSi₂O₇, HT) with good mechanical properties as a matrix and Mg-doped biodegradable mesoporous bioactive glass (MBG) as a coating. The effect of Mg doping on the microstructure and osteogenic activity of the M/HT composite scaffold was investigated. The microstructures of the composite scaffolds were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The osteogenic activity of the scaffolds was investigated with human bone marrow mesenchymal stem cells (hBMSCs). The results show that Mg doping can reduce the mesoporous order of MBG to a certain extent, but Mg-M/HT composite scaffold still has a uniform and ordered pore structure. Compared with M/HT scaffold, Mg-M/HT scaffold has higher intracellular focal adhesion proteins and integrins, as well as alkaline phosphatase, calcium nodules and osteocalcin expression, indicating that Mg doping can promote the osteoblast activity of M/HT scaffold. Mg-M/HT scaffold has a potential application in the field of bone tissue repair.

To reveal the mechanism of the inert gehlenite (C₂AS) phase in sulfoaluminate cement clinker at a low Al₂O₃/SiO₂ ratio, a series of clinkers were prepared at different calcination temperatures and holding time as well as a fixed Al₂O₃/SiO₂ ratio of 2. The evolution of C₂AS was investigated by X-ray diffraction combined with the Rietveld method and thermogravimetry-differential scanning calorimetry. The results show that C₂AS is produced by the reaction of CaO, SiO₂ and Al₂O₃ at 950-1 200 ℃. C₂AS is mainly produced by the reaction of CA and CaO decomposed from C₄A₃$ with the residual SiO₂ when the temperature exceeds 1 200 ℃. It is indicated that the kinetics of the C₂AS formation above 1 200 ℃ is mainly controlled by the diffusion of Ca²⁺, and the activation energy of the reaction is (305±20) kJ/mol. This study provides a a guidance for the use of low-grade bauxite in the calcination of sulfoaluminate cement clinker.

Silicon dioxide (SiO₂) membrane has attracted much attention in the field of separation and purification due to its high-temperature resistance and adjustable pore size. However, the amorphous structure on the surface leads to the mutual restriction of permeability and selectivity, which affects the results of separation. A SiO₂@ZIF-8 composite membrane was prepared with SiO₂ membrane as abase membrane and modified with metal organic framework material (ZIF-8). The effects of synthesis condition of ZIF-8, addition amount of ZIF-8 and temperature of raw material solution on the dehydration inaqueous ethanol solution mixture under pervaporation conditions were investigated. The results show that the regular channel structure in ZIF-8 can provide additional channels for water molecule transport, the water content on the permeate side of the composite membrane is 99.5 %, the permeate flux increasesto 9.6 kg/(m²·h) and the separation factor is 1 973. A relationship between membrane permeation flux and temperature follows the Arrhenius equation. The apparent activation energy of water molecules in the composite membrane is higher, and the water flux increases faster with the increase of temperature, indicating a better separation effect. SiO₂@ZIF-8 composite membrane can effectively improve the defects of amorphous network structure of silica film, which has a broad application prospect in the dehydration of organic solvent by pervaporation.

Membrane separation technology has attracted extensive attention in the fields of seawater desalination and wastewater treatment due to its unique advantages, such as low energy consumption, high separation efficiency, and no phase transition. In this paper, graphene oxide (GO) and dopamine modified halloysite (D-HNTs) composite films were prepared via vacuum filtration with commercial nylon microporous film as a base film. The optimum ratio of film formation was obtained via examining a pure water flux, a hydrophilic performance, and a retention performance of composite films. The application of composite film in the field of liquid filtration was presented. The results show that the interlayer transport channel of composite film becomes greater with increasing the proportion of D-HNTs in composite film. Among them, at a mass ratio of GO∶D-HNTs of 6∶4, GO film formation is complete, the corresponding rejection rate of methylblue is 97.28%, and the pure water flux reaches 123.14 L/(m²·h) under a transmembrane pressure of 0.1 MPa. In addition, a pollution experiment was also carried out for 3 cycles with bovine serum albumin as a pollutant. The water flux recovery rate of composite film can reach >96%, indicating the superior anti-fouling performance.

To investigate the effect of CO gas partial pressure on the morphology and quantity of one-dimensional SiC catalyzed by copper, one-dimensional silicon carbide (SiC) with different morphologies was synthesized by a catalytic reaction method with silicon powder and phenolic resin as raw materials, and copper tartrate as a catalyst precursor. The samples were characterized by X-ray diffraction, field emission-scanning electron microscopy and transmission electron microscopy. The effects of catalyst, atmosphere and temperature on the morphology of SiC were investigated. The results indicate that the worm-like one-dimensional SiC is formed without a catalyst at 1 400 ℃. The Cu-catalyzed one-dimensional SiC with a chain-bead structure was synthesized under an argon atmosphere at 1 200 ℃, and the Cu-catalyzed one-dimensional SiC with a core-shell structures was synthesized under a CO atmosphere at 1 200 ℃. The growth mechanism of worm-like SiC is the reaction of gaseous phase CO and liquid phase Si to form a solid-phase SiC (i.e., V-L-S mechanism), and the growth mechanism of SiC with a chain-bead structure and a core-shell structure is the direct reaction of vapor phase SiO and CO to form solid-phase SiC (i.e., V-S mechanism). The results of this work can provide a theoretical basis for the in-situ formation of one-dimensional SiC ceramic reinforced phases with different morphologies in carbon-containing refractories.