Cadmium manganese telluride (Cd_1-xMn_xTe, CMT) is an ideal material for room-temperature radiation detectors, which can be widely used in the fields of medical tests, radiation detection, and astrophysics. The higher partial pressure of Cd during the growth of CMT single crystals by the Bridgman method leads to severe volatilization of Cd, which in turn produces a high density of intrinsic point defects, such as Cd vacancies. This reduces the resistivity of the crystal and alters the conductive type of the crystal, making it difficult for the crystal to meet the requirements for device preparation. In this paper, CMT crystals were grown by a vertical Bridgman method with Te solution. The compositions were co-doped with In/V at 10¹⁷ atom/cm³ to compensate for the Cd vacancies and increase the crystal resistivity.

In addition, the electrical properties of Au, Ag, Al and In electrodes in contact with CMT semiconductors were also investigated.

Te (9N), Cd (9N), In (9N), Mn (5N), and V (5N) were used as raw materials in a pellet form (Sichuan Ehalf High Purity Materials Co., China). Cd_0.9Mn_0.1Te single crystals co-doped with In and V (doping concentrations of 2×10¹⁷ atom/cm³ and 3×10¹⁷ atom/cm³, respectively) were grown by a vertical Bridgman method with Te solution. The grown ingots were 95 mm in length and 30 mm in diameter, and a diamond wire cutting machine was used to cut wafers with a thickness of 2 mm at the head, middle and tail of Cd_0.9Mn_0.1Te:In/V ingots, and further cut single crystals of 10 mm×10 mm×2 mm. The head, middle and tail single crystals of Cd_0.9Mn_0.1Te:In/V ingots were tested for the crystal structure by a model D/M-2500 X-ray diffractometer, respectively. The optical properties of crystals were determined by Fourier transform infrared spectroscopy and UV-visible-near-infrared spectroscopy.

Four single-crystal samples in the middle of Cd_0.9Mn_0.1Te:In/V ingot were selected as CMT detector materials. Au, Ag, Al and In metal electrodes were deposited on the surface of the crystals by a model KYKY-SBC-21 vacuum evaporation machine. The four metals were deposited by using 4N-grade high-purity evaporation wires with a diameter of 0.5 mm and a length of 80 mm. In order to ensure a low background noise in the detector, a low leakage current of the crystal was required and the electrodes were passivated with hydrogen peroxide after preparation. Au and In electrode CMT detectors were annealed in a model OTF-1200X tubular annealing furnace at different temperatures (i.e., 350, 370, 390, 410 K and 430 K) for 1 h, respectively. The electrical performance of CMT detectors with different electrodes was tested by a model agilent model 4155c semiconductor parameter analyzer.

Cd_0.9Mn_0.1Te:In/V single crystal is a crystal structure of sphalerite, in which the diffraction peak (111) has the maximum intensity, indicating that the preferred crystal growth direction is the direction (111). The average IR transmittance of the single crystal in the middle of the ingot is 67.3%, which is the maximum value reported in the literature. The high IR transmittance of In and V co-doped Cd_0.9Mn_0.1Te crystals is attributed to the fact that the double dopant adequately compensates for the acceptor defect Cd vacancies and reduces the vacancy defect concentration.

The average roughness of Ag, Ag, Al and In electrodes deposited on the surface of CMT crystals are all below 20 nm. Based on the results of electrical performance tests, the ohmic coefficient of Au electrode is close to 1, and the ohmic contact performance of Al and Ag electrodes is poorer. The adaptability of different materials to the annealing temperature is different, the leakage current of Au electrode decreases as the annealing temperature increases to 390 K. The leakage current of In electrode decreases only slightly after annealing at 350 K, and the leakage current of In electrode is greater than that of the unannealed one after annealing at >370 K, indicating that there is a limitation of annealing on the improvement of the electrical properties of the In electrode.

The forbidden band width of Cd_0.9Mn_0.1Te:In/V single crystal was 1.52 eV, and the IR transmittance of the middle crystal was 67.3%, indicating that the middle crystal had superior optical properties. Al, Ag, In and Au electrode materials all formed ohmic contacts with the CMT, with the optimum electrical performance of Au and In electrodes. The optimum annealing temperatures for Au and In electrodes were 390 K and 350 K. Au and In electrodes were annealed at 390 K and 350 K, respectively. Au could be the most suitable electrode material for Cd_0.9Mn_0.1Te:In/V single-crystal radiation detectors.

Alkali-activated slag (AAS) cementitious material has attracted much attention due to its high early strength, good corrosion resistance, and low carbon emission. The microstructure of AAS has a decisive influence on its properties, which depends on the quantity and spatial distribution of the reaction products. It is thus of great significance for understanding the formation process of its microstructure to explore the distribution of reaction products in AAS system. In previous studies, the type of activator and the dosage of sodium oxide both have an effect on the microstructure of AAS. However, the underlying mechanism of sodium oxide content affecting the microstructure of AAS system via the product distribution is still unclear. In this paper, the dissolution behavior and product distribution characteristics of slag in sodium hydroxide solution with different concentrations were in-situ observed by a polarizing microscope. The dissolved ions, phase composition, microscopic morphology, distribution characteristics of reaction products, and pore structure of hardened AAS were also analyzed to elucidate the difference of reaction process of slag at different concentrations of sodium hydroxide solution.

Sodium hydroxide solutions with molar concentrations of 0.5, 2.0 mol/L and 4.0 mol./L were prepared. Slag was uniformly mixed with sodium hydroxide solution at a solid/liquid ratio of 1/100. 1-2 drops of the mixture were added into a single concave slide by a dropper. The excessive solution was removed with absorbent paper and the edges of the cover slip were sealed with paraffin. The prepared slide sample was placed on the stage of the polarizing microscope and independent slag particles were selected for the coming characterization. The area change rate of slag particles or reaction products was analyzed by a software named Image J. The surface morphology of slag and the distribution of reaction products were characterized by scanning electron microscopy, and the elemental analysis of different morphological substances was determined by energy-dispersive X-ray spectroscopy.

After the mixed samples were stayed for 1, 6 h and 48 h, pore solutions were obtained through centrifugation and filtration, and the reaction products in the precipitate were dissolved by a methanol-salicylic acid solution. The ion quantity was determined by inductively coupled plasma optical emission spectroscopy. After the mixture was stayed for 6 h and 48 h, residual solids were obtained after centrifugation. In the hydration of residual solids, the phase composition was analyzed by X-ray diffraction, and the reaction degree was determined by a selective dissolution method.

The alkali-activated slag pastes with different sodium oxide contents (i.e., 4%-8%) and a water-solid ratio of 0.4 were prepared. After standard curing for 3 d, the samples were broken, and then the hydration was terminated and dried. The dried samples were placed into the dilatometer, and the pore size distribution was determined by a model Auto pore IV 9500 mercury injection instrument.

At a low concentration of sodium hydroxide (sample N1), the ion dissolves slowly because of the slow depolymerization of slag. Since the saturation concentration is not reached, the dissolved ion continues to diffuse outwards, forming a new gel phase zone containing a great amount of water, which makes the initial dissolved precipitate products distributed in a wide range. After 48 h reaction, the area of this region is increased by 257.8%, compared to the initial area of slag. The main reaction products are C-(A)-S-H gel and hydrotalcite.

At a high concentration of sodium hydroxide (samples N2 and N3), [SiO₄]^4- and Ca²⁺ are dissolved in large quantities due to the rapid depolymerization of slag. Calcium hydroxide crystallizes out because its saturation index is greater than 0. Also, ion concentration rapidly reaches the solubility product (K_sp) of calcium silicate hydrate, forming a layer of dissolve-precipitate reaction products on the surface of slag particle. Therefore, the product distribution range of AAS system with a high concentration of sodium hydroxide is narrow. The area growth rates after 48-h reaction for samples N2 and N3 are 15.6% and 4.0%, respectively. The reaction products mainly consist of C-(A)-S-H gel, hydrotalcite, katoite and portlandite.

At the same curing age, AAS with a high sodium oxide content has a higher reaction degree and a lower porosity, compared to AAS with a low sodium oxide content. However, AAS with a high sodium oxide content has more macro-pores due to the difference in the distribution characteristics of reaction products.

The concentration of sodium hydroxide had an influence on the product distribution in AAS system. For the AAS system with a low concentration of sodium hydroxide, the ions dissolved slowly and spread outward continuously, forming a new gel phase around the slag, and then polycondensation and dehydration with the area increment rate of 257.8%. For the AAS system with a high concentration of sodium hydroxide, the slag quickly dissolved a large number of silicate and calcium ions, resulting in the saturation index of calcium hydroxide of greater than 0 and the formation of portlandite crystals. The distribution range of reaction products was relatively narrow with the area growth rate of less than 15.6% because the surface of the slag particles was quickly covered by reaction products. Although the hardened AAS paste with a high Na₂O content had a higher reaction degree and a smaller porosity, compared to AAS with a low Na₂O content, the size of pore was larger.

Magnesium phosphate cement (MPC) is a novel construction material that forms a gel material consisting primarily of insoluble phosphate salts after reaction of alkaline components with magnesia and soluble acid phosphate salts. However, the ceramic properties of MPC are significantly deficient in terms of fatigue resistance and toughness, and can lead to failure under vehicle loads. Short-cut basalt fibers can inhibit the initiation and propagation of concrete microcracks, but tend to wrap around and agglomerate during mixing. In addition, China has abundant island reef resources, and large quantities of concrete materials are required in various infrastructure construction processes. Transporting sand and fresh water from inland increases project costs, and extreme climate conditions can cause transportation inconveniences. Therefore, the use of seawater and marine sand from island reefs for road repair without damaging the environment can achieve a goal of localizing raw materials and reducing transportation burden. In this paper, effect of resin-modified basalt fiber on the workability, mechanical properties, fatigue resistance, microstructure, and engineering properties of seawater-sea sand MPC mortar was investigated.

Dead-burned magnesia, ammonium dihydrogen phosphate, borax retarder, highly active silica fume, and ultrafine low-calcium fly ash were used to prepare two groups of mortars with seawater sea sand or freshwater river sand. The modified basalt fiber was prepared, in which the surface of the modified fiber after coating with resin has a twist and wrinkle, which strengthens the bite force between the fiber and the mortar matrix. Different meshing structures were formed between the mortar and the end head (lengths of 23-25 mm, tensile strength of 2 900 MPa, Young modulus of 90 GPa). The basalt fiber with different volume fractions (i.e., 0%, 0.25%, 0.50%, 0.75% and 1.00%) was added to investigate the effect of fiber content on the matrix properties.

The workability (flowability, setting time), mechanical properties (compressive/flexural strength), and fatigue resistance (sinusoidal reciprocal loading: 0.6, 0.7 and 0.8) of the MPC mortar were investigated in accordance with the standard for test methods of basic properties of construction mortars (JGJ/T 70—2009). The heat release, mineral phase composition, microstructures, and pore structures of the MPC mortar were investigated by a hydration thermal analysis, X-ray diffraction, field emission scanning electron microscopy, and X-ray computed tomography. The field rapid repair tests were conducted to comprehensively evaluate the structural layer characteristics of the surface layer by three-dimensional ultrasonic scanning, falling hammer bending, rebound, and coring methods.

The hydration time of sea water-sea sand MPC mortar is short at a setting time for 30 min. The mortar can be compacted without vibration due to its workability available. However, the high dosage of modified basalt fibers has a challenge to fully wet the particle surfaces, increasing friction between particles and adversely affecting the workability of MPC mortar.

The strength development of sea sand MPC mortar progresses rapidly with a compressive strength of 22 MPa after 1 h. The addition of a small amount of modified basalt fiber can slightly enhance the compressive strength of the MPC matrix. The fibers act as bridges in the fracture zone, improving the flexural deformation capacity of the MPC mortar. At different stress levels, the samples with 0.75% fiber content exhibit a fatigue life approximately one order of magnitude higher than that of mortar without fiber addition.

In the hydration process of seawater/sea sand MPC mortar, a highly exothermic reaction occurs with the heat release primarily concentrated within the first hour, exhibiting a single peak. The crystalline phase content increases during the condensation and hardening process of MPC with major hydration products including struvite stone, sillimanite, and monticellite. Also, the introduction of seawater/sea sand leads to the formation of sulfate-chloride products. The hydration products of phosphate crystals form a strong bonding interface between the binder and an appropriate amount of modified basalt fibers. However, the incorporation of 1% fibers results in larger defects at the fiber-matrix interface, an increased internal porosity, and greater non-uniformity in pore distribution.

Based on on-site experiments, the reliability of seawater-sea sand MPC mortar in repair projects is confirmed. The mortar pouring is convenient, the process is simple, and the surface consolidates and hardens quickly. The results obtained after 1 h of pouring indicate that although the bond between the newly poured MPC mortar and the bottom crushed stone layer is relatively weak, the overall integrity within the new surface layer is good, and the density is high. The surface rebound values and maximum deflection values are distributed evenly, and the strength at the interface between the pouring surface and the old concrete pavement is relatively low.

The setting time of the early-strength MPC mortar could be controlled within 30 min. Fibers could improve the bending deformation capacity of MPC, and the fatigue life of the samples with 0.75% fiber content was increased by approximately an order of magnitude, compared to the samples without fibers. The hydration reaction of the mortar was a highly exothermic process, accompanied by an increase in crystalline phase content. The gel composed of struvite and modified basalt fiber had a strong bonding interface, while the porosity and pore variability increased with the increase in fiber content. Besides, the newly poured MPC surface layer had a high compactness in engineering application, and the distribution rebound values and deflection values was uniform, confirming the feasibility of fiber-reinforced sea sand/sea water mixed MPC system.

Lithium sulfur batteries have attracted recent attention as the secondary batteries with a high specific energy, a long lifespan, and a high safety. Inhibiting the shuttle effect of polysulfides and improving reaction kinetics become challenges. The chemical interactions between polar metal compounds and polysulfide ions (i.e., polarity polarity interactions, Lewis acid-base interactions, and sulfur bond chain reactions) have some advantages in inhibiting the shuttle effect of polysulfide ions. In addition, many metal compounds exhibit an electrocatalytic activity during the conversion of polysulfides, promoting the conversion rate of polysulfide ions during charging and discharging, suppressing the uneven deposition of insoluble sulfides Li₂S₂/Li₂S on the electrode surface, and thus achieving a goal of improving the utilization rate of active substances, inhibiting shuttle, and reducing the loss of active substances. The inherent conductive properties of conductive polymers are conducive to electron conduction, and their soft and elastic properties can effectively buffer the volume expansion of active substances during charge and discharge processes. The functional groups rich in them have a strong affinity for LiPSs and can inhibit shuttle effects. In this paper, Fe₂O₃@PPy composite materials were prepared via in-situ growth of polypyrrole on Fe₂O₃ nanosheets by acid etching.

Fe₂O₃ nanosheets were modified by a simple one-step method with polypyrrole to prepare high-performance lithium sulfur battery composite cathode materials. Fe₂O₃ nanosheets were placed in a solution of p-toluenesulfonic acid, and the surface was exposed to Fe³⁺ by acid etching. Fe³⁺ acted as an oxidant to promote the oxidation polymerization reaction of pyrrole monomers on the surface of the nanosheets. Also, p-toluenesulfonic acid was doped into the molecular structure of polypyrrole to obtain Fe₂O₃@PPy composite nanosheets. A series of Fe₂O₃@PPy composite nanosheets were prepared via adjusting the etching environment and the feeding amount of Fe₂O₃ nanosheets to control the modification amount of polypyrrole.

The in-situ growth method induced by acid etching was used to modify the surface of α-Fe₂O₃ nanosheets with polypyrrole, in which p-toluenesulfonic acid played an etching and doping role. Fe³⁺ ion etched on the surface of Fe₂O₃ nanosheets is used as an oxidant, allowing pyrrole to polymerize and grow on the surface of Fe₂O₃ nanosheets. P-toluenesulfonic acid is doped into the molecular structure of polypyrrole as a para anion, resulting in Fe₂O₃@PPy composite nanosheets. The obtained Fe₂O₃@PPy nanocomposites combine the catalytic active sites exposed by Fe₂O₃ nanosheets with a high conductivity and a high specific surface area of polypyrrole. This increases the chemical adsorption of polysulfides and inhibits their shuttle, and accelerates the conversion of soluble LiPSs to insoluble products, greatly improving the utilization rate of sulfur, helping to improve the ion/electron transfer rate of nanosheets, and enhancing the reaction kinetics of electrode materials. Fe₂O₃ nanosheets form reinforced chemical bonds with LiPSs and promote the conversion of polysulfides, which effectively alleviates the shuttle effect of polysulfides, and improves the Coulomb efficiency, cycle stability and capacity retention of batteries. Polypyrrole enhances the conductivity of Fe₂O₃ nanosheets, their surface ion and electron conductivity, and improves Li⁺ diffusion kinetics. At a molar ratio of p-toluenesulfonic acid to Fe₂O₃ of 12∶1, Fe₂O₃@PPy composite nanosheets exhibit a superior electrochemical performance. The discharge specific capacities of the S@Fe₂O₃@PPy-3 cathode at 0.1, 0.2, 0.5 C and 1.0 C are 734.7, 576, 468.7 mA·h·g^-1 and 405.2 mA·h·g^-1, respectively. At a current density of 0.1C, S@Fe₂O₃@PPy-3 cathode can recover more reversible capacity with a discharge specific capacity of 519.5 mA·h·g^-1, having a superior rate performance. S@Fe₂O₃@PPy-3 provides an excellent cycling performance, maintaining a capacity of 414.5 mA·h·g^-1 even after 500 cycles at a high rate of 1 C with a capacity retention rate of 86.2%. This material can be used to the development of power batteries.

The synergistic effect of Fe₂O₃ and PPy on the electrochemical performance improvement of lithium sulfur batteries was effective. According to the change in the relative content of polypyrrole on the surface of Fe₂O₃ nanosheets, the conductivity of Fe₂O₃ nanosheets improved with the increase of polypyrrole content. However, the excess polypyrrole nanoparticles covered the surface of Fe₂O₃ nanosheets at the excessive polypyrrole, leading to a decrease in active sites and in battery performance. In summary, as a carrier for sublimation of sulfur, Fe₂O₃@PPy could promote the adsorption of polysulfides and alleviate their shuttle effect, improving the utilization rate of sulfur in lithium sulfur batteries.

The existing fluorescence regulation of Ni²⁺-doped GCs is studied, having a great potential in broadband amplifiers, tunable lasers, non-invasive sensing, infrared night vision sources, and infrared medical diagnosis. Numerous studies indicate that 1) the NIR emission band and bandwidth of Ni²⁺ can be regulated via controlling the types (oxides, fluorides) and modes (single phase or dual phase) of crystals in GCs; 2) the luminescence intensity of Ni²⁺ can be further enhanced by energy transfer through sensitizers such as Nd³⁺, Yb³⁺, Cr³⁺, etc..; 3) the luminescence intensity of Ni²⁺ can be also enhanced by optical field regulation, such as using noble metal nanocrystals to improve the collection efficiency of pump light.

However, Ni²⁺-activated transparent GCs still have some challenges. The doping concentration of Ni²⁺ in microcrystalline glass and microcrystalline glass fibers is relatively low, usually less than 0.2% (in mole fraction), resulting in low NIR absorption coefficients; The matrix glasses that can carry Ni²⁺ activation are still limited. Exploring multi-component glass matrices that can precipitate new types of crystal phases is one of the main tasks; Residual Ni²⁺ at the glass phase or glass-crystal phase interface still accounts for a large proportion. Some strategies are needed to ensure that most Ni²⁺ enters the target crystals, further improving its infrared optical performance; The gain coefficient of Ni²⁺-doped microcrystalline glass/fiber is relatively low (<0.3 cm^-1) due to the limited volume ratio of nanocrystals in the glass (i.e., crystallization rate) and the influence of surface/interface defects of nanocrystals. Meanwhile, efficient positive feedback cannot be formed due to the lack of high-quality resonant cavities, resulting in only room-temperature luminescence of Ni²⁺, and no laser emission is achieved yet. The prerequisite for achieving laser emission is to obtain laser materials with sufficient gain.

The Purcell effect can accelerate the radiation relaxation process of luminescent materials, resulting in an increased radiation probability and a correspondingly increased quantum efficiency of photoluminescence. Based on whispering gallery mode (WGM) glass microspheres, light can be confined in the micron-scale cavity for a long time based on the principle of total reflection. Therefore, it has an extremely high quality factor (i.e., ≥10⁵) and minimal mode volume (i.e., ≤10³ μm³), which can fully utilize the Purcell effect to enhance the interaction between light and matter. With the unique advantages of the WGM glass microsphere cavity, the preparation of a new Ni²⁺-doped microcrystalline glass microsphere laser provides an effective way to break through the physical bottleneck of room-temperature Ni²⁺ laser emission and develop low-threshold, ultra-broadband near-infrared multi-wavelength micro-lasers.

In this review, the application of diamond materials in deep space exploration (detectors), portable power supplies (isotope batteries), spacecraft thermal control (heat conduction and near-field thermal radiation devices), spacecraft health monitoring (quantum sensors), and optical windows (optical sensor windows were proposed). To represent the application advantages of diamond in the extreme field of aerospace, it is necessary to continue efforts in at least the following aspects. First, 2-inch large-area array polycrystalline diamond arrays are reported to have a good ultraviolet detection performance, and it is possible to effectively synthesize large-area heteroepitaxial single crystal diamond for diamond detectors with better electrical properties. Second, diamond isotope cells and near-field thermal radiation devices both are based on the construction of diamond semiconductor heterojunctions, but the effective diamond N-type doping technology has not yet been broken through. It is thus necessary to further develop the effective diamond doping technology based on new principles. Finally, diamond quantum sensing technology has the advantages of multi-parameter sensing, but how to distinguish the output signal under different field signal excitations and reduce the interference in the face of multi-source targets needs to be further investigated.

The importance of environmental protection leads to the development on new energy hydrogen production technology. High-temperature solid oxide hydrogen production technology is widely investigated because of its non-polluting production process and close to 100% hydrogen production efficiency. However, the solid oxide electrolytic cell (SOEC) cannot be commercialized because of its short effective service life, in which the electrode degradation effect caused by the uneven distribution of reactant water vapor is one of the important reasons for the short life span of the SOEC. The flow inhomogeneity of the conventional parallel flow channel significantly affects the reaction efficiency and service life of solid oxide electrolytic cells, and the flow uniformity is dependent on the geometry of the SOEC flow channel. For the flow characteristics of the conventional Z-type solid oxide electrolytic cell, the molar fraction of water vapor gradually decreases from the two ends to the middle region, which affects the performance of SOEC. To improve the uniformity of water vapor distribution from the structure, a new channel structure was designed to change the width of the channel in accordance with a certain cross-sectional area ratio. The cross-sectional area of the channel from the two ends to the middle could be gradually increased to enhance a supply of water vapor in the middle region, so as to make the overall distribution of water vapor in the SOEC more uniform, eliminate the electrode degradation effect and prolong the service life of the solid oxide electrolytic cell.

The total cross-sectional area of the entire flow channel remained unchanged. Based on the characteristic of the water vapor mole fraction of the conventional Z-type flow channel that decreases regularly from the two sides to the middle, a control variable method was adopted according to a certain ratio of the width of the flow channel to calculate the size of the cross-sectional area of each channel. Different water vapor mole fractions of the different flow channels were used. A three-dimensional model of a Z-type flat plate solid oxide electrolysis cell with uniform and non-uniform channel widths was proposed. The continuity equation, momentum equations, energy equation, species transport equation coupled with the Nernst equation and the BV equation were numerically solved by a software named COMSOL to simulate the water vapor molar fraction, local current density, pressure drop, temperature and heat production power in the flow channel. The flow field characteristics of the conventional Z-type flow channel and the improved channel structure were obtained via simulating the process of solid oxide electrolysis of water.

The non-uniformity coefficient at electric current densities from 1 000 A/m² to 8 000 A/m² at different channel width ratios (i.e., 1.000 0, 0.957 0, 0.920 0, 0.887 6, and 0.858 6) are simulated. The lowest inhomogeneity coefficients of the solid oxide electrolytic cell are obtained at all current densities when the channel width ratio is 0.920 0. Also, the non-uniformity increases with the increase of current density. When the current density is 8 000 A/m², the non-uniformity coefficient is 0.152 for the traditional channel, but the non-uniformity coefficient for the optimized channel is 0.030 4 at a channel width ratio of 0.920 0, indicating that the distribution of water vapor mole fraction in the solid oxide electrolysis cell is the most uniform, with the difference in water vapor molar fractions between the middle and two end channels is only 10.2%. The hydrogen production rate is increased by 7%, compared to the traditional channel. Meanwhile, as the water vapor distribution becomes more uniform, the temperature difference of the solid oxide electrolytic cell decreases from 105.9 K to 97.2 K. The temperature uniformity is also significantly improved, thus reducing the electrode degradation effect and the risk of thermal stress concentration due to the electrochemical heat.

Changing the width ratio of Z-type channel could affect the distribution of water vapor. In the absence of water vapor in the middle region of the Z-channel, the flow field uniformity of the Z-channel optimized at a width ratio of 0.920 0 could be greatly improved. The main reason was that the cross-sectional area of the flow channel in the middle region was proportionally expanded, so that more water vapor was provided to the part lacking water vapor in the middle, and the electrolytic capacity of the electrolytic cell could be developed. The effect of electrode degradation was eliminated. This study indicated that the flow field inhomogeneity of the parallel flow channel itself could be mitigated via changing the geometry of the solid oxide electrolytic cell, which was more advantageous in terms of reprocessing cost and effectiveness rather than adding a flow distributor or using metal foam filling to improve the flow field distribution uniformity.

As an important source of strength in cement-based materials, the structural characteristics of C-S-H gel in microscale can determine its macroscopic applications in different fields. This review represented the typical structures of C-S-H gel at different stages and introduced the inherent connection between structure and performance. The precise control of different C-S-H structure using hydrothermal synthesis was introduced, and the influence of synthesis factors on its composition, morphology, and structure was described. The basic research on the synthesis of C-S-H gel in relevant fields was summarized. This review summarized the relationship between the structure and performance of C-S-H gel as well as the exploration of the prospects for the engineering application of C-S-H gel. This review provided a theoretical reference for fully understanding the hydration mechanism of cement and developing high-performance, environmentally friendly building materials. At present, the research on the essence and mechanism of C-S-H gel is still relatively weak, and there are still many problems to be solved and further explored:

1. This review mainly summarized the influence of synthetic C-S-H gel doped with cement-based materials on the overall performance, but could not realize an integrated study of "structure-performance-application" of C-S-H gel. It is necessary to deeply analyze the influence of the structure and performance of cement hydrated C-S-H gel on the matrix, and further improve the growth regulation and performance application of C-S-H gel in cement concrete.

2. In the process of hydrothermal synthesis of C-S-H gel, the influence and law of key variables such as Ca/Si ratio, alkali ion, reaction time and temperature on the particle size are not determined yet. In the future, it is necessary to continuously debug the experimental environment and parameters to explore a relationship between the particle size and properties.

Titanium (Ti)-based implants are one of the most commonly used materials in orthopedic surgery. Although Ti-based implants have good biomechanical properties and biocompatibility, their non-antibacterial shortcomings lead to orthopedic implant-related infections that seriously affect the effect of surgery and postoperative recovery. and serious cases need a second operation and increase the pain and cost of patients. Some studies reported metal or antibiotic antibacterial coatings on Ti-based implants, but they have some disadvantages (i.e., heavy metal coatings can cause damage to the human body, and excessive use of antibiotic coatings can lead to drug resistance). It is thus necessary to investigate the preparation of coatings with good antibacterial properties and biological activities on the surface of Ti-based implants, so as to provide an effective solution to the problem of bone implant-related infection in clinic. Magnesium (Mg) is a major element in human body. Some studies reported that Mg and its compounds have good antibacterial and biocompatibility.

Ti sheets were cleaned and immersed in an electrolyte containing sodium chloride and magnesium chloride (pH=9.5) and applied a DC voltage of 3.0 V for 0-12 h to obtain magnesium hydroxide [Mg(OH)₂] coatings. After deposition, Mg(OH)₂ coatings were calcined in a muffle furnace at a heating rate of 2 ℃/min at 650 ℃ for 6 h to obtain magnesium oxide (MgO) coatings. The phases of each group of samples were analyzed by X-ray diffraction (XRD), the surface morphology was analyzed by scanning electron microscopy (SEM) and the composition of surface elements was analyzed by energy dispersive spectroscopy (EDS). The in-vitro antibacterial properties of the samples were evaluated according to the standard ISO22196—2011. The bacterial liquid was resuscitated, diluting it to 1 × 10⁵ cfu/mL (cfu is colony-forming units). The samples were firstly sterilized by drying, then 300 μL bacterial solution (i.e., Staphylococcus aureus and Escherichia coli) was then dropped onto each sample and incubated in a constant temperature incubator (at 37 ℃) for 24 h. After diluting the coating plate, the colony number was analyzed and converted to antibacterial rate. The in-vitro cytotoxicity of each sample was evaluated according to the standard ISO10993.5. After dry heat sterilization, the samples were placed in a 24-well plate (no sample cell suspension in the control group and complete culture medium in the blank group). 1mL mouse osteoblast suspensions (OB-6; 5 000 cell/mL) were dropped onto each sample and then incubated in a cell culture box (5% CO₂ at 37 ℃) for 1 d, 3 d or 5 d. After the completion of culture, the absorbance value was detected by a method named CCK-8 and converted to a cell survival rate.

Mg(OH)₂ coating was prepared on titanium surface by an electrochemical deposition method, and MgO coating was obtained after calcination. Granular matter [Mg(OH)₂ and MgO] are uniformly distributed on the surface of each group, and the particle density and coverage rate increase with deposition time. Mg(OH)₂ and MgO coatings all have a good antibacterial activity against Staphylococcus aureus and Escherichia coli. The antibacterial rates increase with deposition time. When deposited for≤3 h, the antibacterial rate of MgO is higher than that of Mg(OH)₂. After deposited for ≥6 h, the bacteriostatic rate of both is close to 100%. The cytotoxicity of Mg(OH)₂ and MgO coatings increases with the deposition time, and the toxicity of the two groups (i.e., deposited for 0.5 h and 1.0 h) decreases with the culture time, and the toxicity of the other three groups (i.e., deposited for 3 h, 6 h and 12 h) increases with the culture time. At 5 d, the survival rates of Mg(OH)₂ and MgO samples deposited for 0.5 h are 152% and 90%, and the survival rates of the two groups of samples deposited for 12 h are 2% and 6%, respectively.

The surface morphology and thickness of Mg(OH)₂ and MgO coatings changed with the deposition time. The cytotoxicity and antibacterial rate of the coatings were enhanced with the deposition time. It was speculated that there was a dose-effect relationship between them and the coating. The results showed that Mg(OH)₂ coating could be prepared by electrochemical deposition, and the MgO coating could be obtained after calcination. Mg(OH)₂ and MgO coatings deposited for 1 h had good comprehensive properties.

Biomass as a near-zero emission and novel energy source is regarded as an optimal alternative to fossil fuels. Biomass gasification technology is extensively used due to its superior efficiency in energy utilization, environmental congeniality, and sustainability. However, tar as a predominant by-product of this process presents some formidable challenges, i.e., combustion difficulties, potential clogging of boiler flue gas ducts, damage to gas-operating machinery, and health risks. These issues constitute a significant impediment to the industrial deployment of biomass gasification technology. Addressing the efficient processing of tar is pivotal for the extensive utilization of biomass gasification. The strategy of employing catalysts for the catalytic reforming of tar to produce hydrogen is emerging as an effective solution, characterized by lower requisite temperatures and enhanced conversion rates. Biomass-derived carbon with its cost-effectiveness, high specific surface area, and outstanding thermal stability is projected to have a significant potential in the transformation of biomass tar. Nevertheless, the suboptimal metal loading capability in the catalyst preparation from biomass carbon results in a reduced catalytic activity and an inferior hydrogen selectivity during the reforming process. Furthermore, there is a notable deficiency in research pertaining to the tar produced in actual production processes. Consequently, there is an urgent need for comprehensive investigations into the mechanism of hydrogen generation via catalytic reforming using biomass-based carbon catalysts.

An apricot shell powder with a granularity of 100-150 mesh was utilized as a feedstock for char production. A biomass char carrier was obtained via carbonizing this material at 350 ℃ for 30 min. Subsequently, the biomass char carrier was impregnated and stirred in a 1 mol/L KOH solution for 3 h, followed by a filtration process, with an impregnation ratio of 1 g of char carrier to 10 mL of KOH solution. The impregnated material was firstly calcined at 300 ℃ for 2 h, and then at 800 ℃ for 1 h 30 min. For post-activation, the biomass char underwent oxidative modification. It was washed to a pH value of 7, impregnated with a 15% hydrogen peroxide solution for 3 h, further washed until the pH value was 7, and then dried the post-filtration. Nickel and cobalt were chosen as metals for loading by impregnation. A 100 mL solution of 1 mol./L Ni(NO₃)₂ and Co(NO₃)₂ was prepared, and a mixture of cobalt nitrate and nickel nitrate was configured in a ratio of 1∶4 to produce a 100 mL mixed solution. This solution was then impregnated with the prepared char carrier in a water bath at 90 ℃ for 4 h and filtered. After drying for 12 h, the material was calcined at 800 ℃ for 4 h.

For the experiment, a cold trap method was employed to collect tar at the outlet of a straw gasifier under atmospheric pressure. The experiment primarily utilized a vertical tube furnace, enabling the catalytic reforming of tar inside a quartz tube. A catalyst bed was placed inside the tube furnace. A basket containing tar was set in the quartz tube in the heating furnace. In the tube furnace, the tar transformed into a gaseous phase and passed through the catalyst bed, undergoing a reforming reaction with the catalysts on the bed. The reaction products entered two conical flasks containing dichloromethane at the lower part of the tube furnace. These flasks were placed in an ice bath pot to collect the residual tar, and after drying, the gases were collected in gas bags for gas chromatographic analysis. The prepared catalyst was characterized by specific surface area analysis, scanning electron microscopy and X-ray diffraction.

The XRD patterns indicate that during thermal treatment, nickel forms metal-carbon complex compounds with surface carbon, while cobalt results in cobalt oxide formation on the biomass char surface. The SEM images revealed a porous structure on the Ni/C surface, with metal-carbon complexes causing indentations on the char carrier, evidenced by visible surface metal particles. A distinctive feature of Co/C compared to nickel-based catalysts is the presence of etched grooves on the surface. The EDS analysis showed an even distribution of nickel on the Ni/C surface with a localized enrichment, alongside some surface collapse. The nickel loading on the catalyst surface is 12.01%. Cobalt displays a more uniform distribution on Co/C, indicating a fewer cobalt oxide enrichment sites.

The experimental results with and without catalysts for tar catalytic reforming demonstrate that catalyst addition increases a tar reforming efficiency and H₂ and CO contents in syngas. Tar reforming conversion rate increases from 36.12% to 76.67%, and H₂ and CO contents in syngas increase from 22.76% and 28.80% to 25.62% and 32.78%, respectively, while CO₂ content decreases from 27.11% to 17.45%. The results for the temperature impact on tar catalytic reforming reveal that an hydrogen yield initially increases and then decreases having the maximum value at 700 ℃. Tar conversion rate gradually increases from 76.67% to 94.95% with increasing the temperature, finally stabilizing after 800 ℃. An optimal steam/tar ratio (i.e., m_Steam/m_Tar) is 3 based on hydrogen yield, production, and tar conversion rate. Similarly, an optimal tar/catalyst ratio (m_Tar/m_Catalyst) is 2. Comparing single metal catalysts with Ni-Co/C catalyst for tar catalytic reforming, Ni-Co/C composite catalyst has a higher hydrogen yield in the gaseous products (i.e., 72.86%) with reduced production rates of C₂H₄, CO and CO₂.

The preparation of carbon-based metal catalysts consists of two stages, i.e., the preparation of the char carrier and metal loading. The optimal temperature for preparing apricot shell char carrier was 350 ℃. Through KOH activation, its specific surface area increased from 5.502 m²/g to 1 124.16 m²/g, with the formation of abundant mesopores and micropores. Subsequently, H₂O₂ oxidation of the activated char carrier effectively enhanced the oxygen-containing acidic groups on its surface. The char carrier, prepared through carbonization, activation, and oxidative modification, exhibited a well-developed mesoporous and microporous structure suitable for efficient metal loading. On the surface of nickel-based catalysts, complex metal-nickel and carbon compounds formed, whereas cobalt- and iron-based catalysts formed metal oxides. The catalyst surfaces showed a good integration of metal with the carbon carrier, with uniform distribution. The carbon-based catalysts with a large specific surface area and a developed mesoporous structure were suitable for tar catalytic reforming. The results indicated that under nickel-based catalyst conditions, a hydrogen yield of 91.52 g H₂ per 1 kg of tar could be obtained at the optimal parameters for hydrogen production from tar catalytic reforming (i.e., 800 ℃, m_Steam/m_Tar of 3 and m_Tar/m_Catalyst of 2). Cobalt-based catalysts exhibited a stronger catalytic activity and a higher hydrogen selectivity, compared to nickel-based catalysts. However, nickel- and cobalt-based catalysts both demonstrated a lower catalytic activity, compared to the Ni-Co/C composite catalyst.