Statistical structure modeling can help to establish the glass formulation design models to meet the vitrification requirements of different types of high-level waste liquids due to its advantages of high efficiency and accuracy. Taking the glass transition temperature T_g, thermal expansion coefficient α and element leaching rate of Li, Na, B as target properties, we utilized a statistical structure simulation method for the development of nuclear waste glass curing formula. The results show that T_g, α and chemical stability of the glasses can be well simulated with the statistical structural data. It is also indicated that the data predicted by the model are in a reasonable agreement with the measured results at a simulation desirability 0.94. Statistical structure modeling can assist to establish the formula database of the high-level liquid waste vitrification.

Geopolymers have a low immobilization efficiency to oxyanions, such as Se(VI) and Cr(VI). Effects of Ca, Mg and Fe(II) additives on the immobilization of Se(VI) and Cr(VI) in geopolymer were thus investigated. The results indicate that the leaching amount of Se or Cr ions is greater than 60% for the geopolymers without any additives. CaO or Fe(II) has a limited depressive effect on Se(VI) or Cr(VI) leaching from geopolymers, and the corresponding leaching amount of Se(VI) or Cr(VI) is still greater than 40%. However, the leaching amount of Se(VI) or Cr(VI) is lower than 10% for the geopolymers with the addition of MgO. According to the LCF fitting results, Cr(VI) can also exist in the geopolymer network through electrostatic interaction as Se(VI). Besides, MgO or CaO can promote Fe(II) to release its reducibility, thereby reducing approximately 15% of Cr(VI) to Cr(III). Se(VI) can have a bonding interaction with Ca. Fe(II) does not present its reducibility during the solidification of Se(VI). To some extent, MgO, CaO and Fe(II) have a synergistic effect on the leaching of Se(VI) and Cr(VI) from geopolymers. In addition, the mechanical strength of geopolymers with or without these additives can satisfy a requirement for industrial landfill.

Zeolite chabazite (CHA) membranes with a higher Si/Al mole ratio in the zeolite framework were prepared to improve their stability and separation performance. Pure zeolite CHA membranes were synthesized with imidazolium-based ionic liquids (ILs) as a structure-directing agent, which could improve the Si/Al ratio in the framework. ILs could be used repetitively at least 3 times for the synthesis of high-crystallinity zeolites. Under the optimized synthetic conditions, a continued zeolite CHA membrane obtained from an initial gel containing 1-buthyl-3-methylimidazolium bromide ([Bmim]Br) on the mullite tubular supports has a high water flux of 6.3 kg/(m²·h) with a high ion rejection (100%) for pervaporation (PV) separation of 3.5% (in mass fraction) NaCl aqueous solution at 75 ℃. The effects of temperature and feed concentration on the desalination performance of ILs-CHA membranes were also investigated. The water flux increases to 10.3 kg/(m²·h), and their salt rejections are 100% when the operating PV temperature increases at 90 ℃. Zeolite CHA membranes prepared have the superior separation performance even for desalination of 10% NaCl aqueous solution. Furthermore, the ILs-CHA zeolite membrane has a stable separation performance with a stable water flux as well as a high salt rejection in 3.5% NaCl aqueous solution at 75 ℃ for 3.5 d.

In order to solve a problem of Sn-loss and reduce the thickness of MoS₂ during the sulfurization process, the oxygen containing Cu-Zn-Sn precursor thin films were prepared on Mo-coated soda lime glasses via magnetron sputtering ZnO/SnO₂/Cu. The results show that the Sn-loss and the formation of MoS₂ are well inhibited by the utilization of SnO₂ and ZnO. The single-phase CZTS absorbed thin films with the smooth surface, dense grains and good crystal structure can be prepared at 590 ℃. Also, the CZTS solar cells from oxygen containing precursors annealed at 590 ℃ have an optimum power conversion efficiency (PCE) of 5.12% with an open circuit voltage of 590 mV, a short circuit current density of 22.09 mA/cm² and a fill factor of 39.28%.

Developing cathode materials with superior electrochemical activity is of great importance to the application of intermediate-temperature solid oxide fuel cell (IT-SOFC). In this paper, Bi_1-xCa_xFeO_3-δ (BCFx, x=0.1, 0.2 and 0.3) compounds were synthesized via solid-state reaction as a cathode material for IT-SOFC. The phase structure, electrical conductivity, oxygen transport performance, and the electrochemical performances of these compounds were evaluated. The as-prepared BCFx compounds show a single-phase perovskite structure. Among the BCFx materials, Bi_0.8Ca_0.2FeO_3-δ (BCF0.2) oxide has the maximum electrochemical catalytic activity. The polarization resistance of BCF0.2 cathode on symmetrical cell is 0.06 Ω·cm² at 750 ℃ in air. Meanwhile, the maximum peak power density of Ni-(Y₂O₃)_0.08(ZrO₂)_0.92(Ni-8YSZ) anode-supported single cell reaches 730 mW·cm² at 750 ℃. As is indicated by the electrical conductivity relaxation, the favorable oxygen reduction reaction catalytic activity of BCF0.2 can be ascribed to the higher oxygen bulk diffusion and surface exchange coefficient. The results of oxygen reduction kinetics reveal that the dissociation of adsorbed molecular oxygen is a limiting step for oxygen reduction reaction on BCF0.2 cathode.

Calcium silicate hydrate (C-S-H) gels shrink upon drying and swell upon on wetting due to the specific water sensitivity, making that the pore structure of cement-based material depends on its water content. The representativeness and accuracy of the pore structure characteristics and its development obtained in a totally dry state are questionable because of the influence of drying preconditioning. To explore the evolution of pore structure of cement-based materials with respect to water to cement (w/c) ratio, several typical white cement mortars were investigated by low-field nuclear magnetic resonance (LF-NMR) and mercury intrusion porosimetry (MIP). Meanwhile, their permeability coefficients to water were also measured. The results show that the discrete pore size distribution (PSD) achieved by LF-NMR in a water-saturated state can be used to predict the water permeability through a classical Kozeny-Carman model based on the parallel cylindrical pores. The effect of w/c ratio on the pore structure of water-saturated mortars is consistent with that on the water permeability. However, the PSD curves measured by MIP scatter remarkably, which cannot reflect the effect of w/c ratio on the pore structure of mortars. As a result, the pore structural characteristics obtained in a dry state are limited, which makes the typical pore classifications questionable. Since the pore structure plays a fundamental role in interpreting almost all the properties of hardened cement-based materials, it is essential to detect the more relevant pore structure in a water-saturated state through LF-NMR to avoid the effect of drying preparation.

SnO₂ is widely investigated as one of anode materials for lithium-ion batteries due to its natural abundance, low discharge potential (less than 1.5 V) and high theoretical capacity. However, the low electrical conductivity and large volume expansion (300%) during Li⁺ insertion/extraction results in the poor cyclability and rate capability of SnO₂, thus restricting its practical applications. In this study, SnO₂@C/rGO nanocomposites were prepared by an one-step hydrothermal method with SnCl₂, L-ascorbic acid and GO as reactants. The L-ascorbic acid-derived amorphous carbon served as a spacer to inhibit the stacking of rGO sheets and acted as a coupling agent to strongly anchor SnO₂ nanoparticles on the rGO sheets. The as-obtained SnO₂@C/rGO nanocomposite delivers a specific capacity of 731 mA·h/g after 180 cycles at a current density of 0.1 C (1 C= 783 mA/g) and a high reversible capacity of 410 mA·h/g at a large current rate of 5 C. This study provides a promising route for the preparation of high-performance SnO₂ anode materials.

Ti₃C₂ MXene is a novel two-dimensional carbide with an accordion-like lamellar structure. The flakes of Ti₃C₂ MXene can slide or stack under tension or compression, which can change the number and length of internal conductive paths and directly affect the output electrical signals. Thus, Ti₃C₂ MXene can be used as sensing materials to measure the change of stress/strain. Combined with the elastic substrates, this material is used to make flexible sensors to monitor the motions and health signals of human-beings. This paper described the working principle of flexible stress/strain sensors made by Ti₃C₂ MXene composites. Recent methods to prepare the sensors were reviewed, i.e., electrospinning, filtration/coating, impregnation, screen printing, freeze drying, and freeze thawing. The key factors of the methods, i.e., flexible substrate, sensing parameters, sensor structure, detection limit, cycle times, sensing rage, responsive time and gauge factor, were represented. Some applications of the MXene-based sensors were discussed. Finally, the promising development of Ti₃C₂ MXene flexible sensors was outlooked and the problems to be solved were summarized.

Carbon foam composites with a unique porous structure can be widely used in the fields of thermal insulation, energy storage, and absorption. In order to improve their mechanical and thermal-insulation properties, carbon foam composites were modified. Silica (SiO₂) aerogels reinforced carbon foam composites were prepared via compression molding and carbonization with zirconium modified phenolic resin as a carbon origin, SiO₂ aerogels as a reinforcement, and phenolic hollow microspheres as a closed phase. The effect of SiO₂ aerogels amount on the microstructure, compressive and oxidation resistance of carbon foam composites was investigated by scanning electron microscopy, universal testing machine, specific surface area analysis and pore size distribution measurement, respectively. The thermal conductivity of pure carbon foam and modified carbon foam composites were characterized by laser-flash thermal conductivity measurement, and their high-temperature heat transfer behavior was then analyzed. The results show that SiO₂ aerogels disperse in the ligaments or on the surface of microspheres, and barely contribute to cell structure of carbon foams. When the SiO₂ aerogels amount is 2% (in mass fraction), the maximum compressive strength and specific compressive strength both reach 19.39 MPa and 42.17 MPa·cm³/g, respectively. Compared to the pure carbon foam, the compressive strength and specific compressive strength of carbon foam are increased by 106.7% and 79.8%, respectively. A proper addition of SiO₂ aerogels can restrict the heat transfer path and internal radiative heat transfer. When the SiO₂ aerogels amount is 5%, carbon foam composites have the optimum thermal insulation and oxidation resistance. The thermal conductivity at 800 ℃ is 0.447 W/(m·K), which is 38.9% lower than that of pure carbon foam. The optimum oxidation resistance can be obtained, i.e., the mass loss of 18% during the isothermal oxidation at 700 ℃ for 30 min.

Hexavalent chromium (Cr(VI)) has attracted much attention due to its high toxicity. In order to improve the efficiency of Cr(VI) removal by adsorption, core-shell structured polyethyleneimine (PEI) functionalized composite nanoparticles (Fe₃O₄@SiO₂-NH₂) were synthesized to remove Cr(VI) in water. The chemical structure, morphology and magnetic properties of the nanoparticles were investigated. The effects of initial concentration, contact time, solution pH value and inorganic anions on the Cr(VI) adsorption efficiency were analyzed. The results show that Fe₃O₄@SiO₂-NH₂ has an excellent performance in removing Cr(VI), and its maximum adsorption capacity is 251.83 mg/g. The adsorption process is pH value-dependent, spontaneous, and endothermic. Fe₃O₄@SiO₂-NH₂ is protonated, and the adsorption of Cr(VI) is completed due to the electrostatic attraction. Also, according to the results by X-ray photoelectron spectroscopy, part of Cr(VI) can be reduced to low-toxic Cr(VI). Fe₃O₄@SiO₂-NH₂ has a good reusability after removing Cr(VI) in water, and the duration for effective magnetic separation after the removal is just 50 s.