Zeolites have broad application prospects in adsorption, separation, catalysis, etc.. Improving their synthesis efficiency and reducing their production cost become a challenge. The synthesis rate of zeolite is low and the production period is long due to the prolonged nucleation and growth of crystals during the crystallization process. Furthermore, commercial high-quality zeolites are mainly synthesized with chemicals as raw materials, resulting in high costs. Therefore, it is significant to develop efficient and low-cost zeolite synthesis technologies. Some previous studies indicate that the use of free radicals could achieve a rapid synthesis of zeolites. Fly ash contains a large amount of silicon and aluminum elements. As a result, the synthesis of zeolite from fly ash reduces costs, and provides a feasible way for its high-value utilization. However, there is little work on the synthesis of zeolite from fly ash assisted by free radicals. It is thus necessary to explore the mechanism of free radical assisted synthesis of zeolite from fly ash, as well as the generation, types and properties of free radicals. Meanwhile, it is revealed that free radicals solve the problem of difficult activation of inert silicon and aluminum in fly ash. The theoretical basis is provided for the development of efficient and low-cost synthesis technology for the preparation of zeolite from fly ash assisted by free radicals, and a reference is provided for other coal based solid waste.

The existence of ·OH in zeolite synthesis systems was firstly discovered in 2016. ·OH was introduced into the synthesis system of NaA, Y, and ZSM-5 zeolites, thus greatly accelerating their crystallization process. This is a high-efficient method for zeolite synthesis besides a microwave method. Meanwhile, electron paramagnetic resonance (EPR) was used to determine hydroxyl radicals, and density functional theory (DFT) was used for the theoretical calculations to investigate the mechanism of hydroxyl radicals accelerating the synthesis rate of zeolite. The catalytic activity by ·OH is greater than that by OH^- for the depolymerization and polymerization of Si—O—Si and Si—O—Al bonds during the nucleation stage, especially in terms of depolymerization. With the continuous deepening of research, the promoting effects of other oxidizing active substances (i.e., reactive oxygen species, superoxide radicals, singlet oxygen, etc.) in zeolite synthesis were also discovered. Moreover, the introduction of free radical methods also opened up a new path for the synthesis of high-quality zeolites from some low-cost silicon aluminum sources with a lower activity. The problem of difficult activation of silicon and aluminum during the synthesis of zeolites from fly ash was discovered, and the positive effect of free radicals on the activation of inert silicon species was demonstrated through the simulation calculations. It is thus speculated that free radicals can improve the problems faced by coal-based solid waste synthesis of zeolite, represented by fly ash. However, little work on the relevant experimental research are made yet, and the further verification is needed. Therefore, free radical introduction methods suitable for fly ash synthesis of zeolite system were discovered, i.e., physical and chemical methods. Among them, adding initiators to produce free radicals in zeolite synthesis using chemical methods is a more feasible method. However, there exist still problems, i.e., some initiators unavailable for the alkaline environment of zeolite synthesis. The research on free radical generation methods suitable for zeolite synthesis environment will provide possibilities for constructing feasible methods for preparing zeolite from low-grade silicon aluminum sources, reducing the synthesis costs, and achieving the green development. Furthermore, some impurities existing in zeolization of fly ash are effectively removed by calcination and acid washing, thereby increasing its silicon and aluminum content, which is conducive to the synthesis of zeolites.

Mesoporous activated carbon as a kind of non-silica-based mesoporous functional material is widely used in many fields such as catalysis, electrochemistry, supercapacitors, biomedicine, and adsorption due to its small pore size (i.e., 2-50 nm), high specific surface area, large pore size and volume of porosity, easy to modify the surface, and good hydrothermal stability. The development of mesoporous materials benefits from the rapid application of mesoporous activated carbon as an adsorbent in the field of adsorption. However, mesoporous carbon is not as widely utilized as mesoporous silica, and mesoporous carbon materials become popular just in recent years.

This review represented recent development on the synthesis and preparation of mesoporous activated carbon materials by physical activation method, chemical activation method, hard template method, soft template method and sol-gel method. The common types of templating agents in the preparation of hard template method and soft template method were enumerated. Silica is widely used as a template, and a class of low-cost, easy-to-remove and environmentally friendly templating agents were derived. The application of excellent magnetic biochar in sol-gel method was analyzed. The physical properties of carbon materials synthesized from different carbon precursors under the condition of H₃PO₄ as an activator were summarized. The control of pore size structure and morphology during the preparation of mesoporous carbon materials obtained by different methods were discussed. The current status of various methods in the preparation of mesoporous activated carbon materials was introduced. The advantages and disadvantages of the various methods in the synthesis of mesoporous activated carbon materials were analyzed. The four types of methods for structural modification and functionalization of mesoporous activated carbon materials by elemental doping of nitrogen, boron, phosphorus and sulfur in non-metals, transition metal doping led by iron, lanthanum, neodymium and cerium-dominated rare metal doping and oxidative modification of surface functionalization were described. The physical properties of carbon materials synthesized from some of the metal doped carbon precursor templates were discussed. The key role of introduction in mesoporous activated carbon materials undergoing structural modification was indicated via the introduction of functional groups through catalytic oxidation by chemical reagents to overcome the intrinsic limitation of limited adsorption capacity. Also, recent development on the adsorption of heavy metal ionsin was mentioned. In addition to some common metal elements, some niche metals (i.e., cobalt) were utilized in doping. In the adsorption of heavy metal ions by mesoporous carbon materials, the sources of heavy metals in water body were introduced, and the application of mesoporous activated carbon materials before and after modification for the removal of heavy metal ions (i.e., mercury, lead, and chromium) in wastewater was briefly described. Compared to the conventional activated carbon adsorbents on the removal of organic pollutants (i.e., dyes, phenols and volatile organic compounds), the mesoporous carbon materials have advantages in the removal of mercury by mercury-sulphur binding, and heavy metals (i.e., lead and hexavalent chromium, etc.). The mechanisms (i.e., electrostatic interaction, ion exchange and surface complexation) in the adsorption process of mercury, lead, and chromium ions were summarized.

Solid-state lithium-ion batteries (SSLBs) are one of the most promising next-generation batteries due to their excellent safety, higher energy density and longer cycle life. Solid-state electrolytes (SSEs) with a high ionic conductivity, a wide electrochemical window, and good mechanical properties are the importance of the high-performance SSLBs. The organic polymer SSEs have some advantages of flexibility and good mechanical property, that makes them almost have no serious interfacial problems. However, the low ionic conductivity is a major drawback for most polymer SSEs. Inorganic SSEs show a high ionic conductivity, a good electrochemical stability, and a high thermal stability, but their main disadvantages are a weak mechanical property (i.e., brittle and fragile), a poor air stability and an inferior compatibility with metal lithium anode. Compared to inorganic and organic polymer SSEs, composite solid-state electrolytes (CSSEs) integrating the merits of organic polymers and inorganic electrolytes exhibit a good electrochemical performance and an excellent interface compatibility, which have attracted extensive attention in the SSEs research. This review detailly summarized the research progress on CSSEs in lithium batteries.

The CSSEs are usually composed of inorganic fillers, organic polymers and lithium salts. The inorganic fillers are classified into inert and active fillers. The inert fillers, such as SiO₂, Al₂O₃ and TiO₂, do not transport Li⁺ themselves, but can promote the ionic properties of polymer matrices. The active fillers conduct Li⁺ themselves including oxides (i.e., perovskite-type, garnet-type, NASICON-type), sulfides, and halides, etc.. Lithium salts used for the investigation of CSSEs include LiPF₆, LiBF₄ and LiN(CF₃SO₂)₂(LiTFSI), etc..

The first CSSE with an inert filler was prepared via introducing an Al₂O₃ into a matrix, thus improving the mechanical property of LiClO₄/PEO CSSEs at 100 ℃. SiO₂ and TiO₂ were a commonly used inert ceramic filler for the fabrication of CSSEs. The content, particle size and shape of metal oxide inert fillers affect the performance of CSSEs. The layered nano-sized claylike montmorillonite (MMT) as a passive filler was doped into polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP) polymer to prepare a ultraviolet (UV)-crosslinked MMT/PVDF-HFP membrane, having a room-temperature ionic conductivity of 1.6×10^-3 S/cm. Carbon materials were also served as inert fillers to prepare CSSEs.

The CSSEs with active fillers were synthesized via adding active fillers to polymers. Li_0.5La_0.5TiO₃ (LLTO) is a typical perovskite-type active filler. The reduction of Ti ions in LLTO with lithium was prevented as combining LLZO with polymers, and the LLZO CSSEs exhibited a wide electrochemical window and a good stability. For instance, a PVDF polymer CSSEs with LLTO nanowires delivers a room temperature ion conductivity of 5.8×10^-4 S/cm, an electrochemical window of 5.2 V, and a mechanical strength of 10 MPa. The cell of Li|PVDF/LLTO-15%/Li⁺|LiFePO₄ (LFP) has a superior Coulomb efficiency of approaching 100% after 200 cycles. The garnet-type active filler Li₇La₃Zr₂O₁₂ (LLZO) and Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) were divided into zero-dimensional nanoparticles, one-dimensional nanowires and nanotubes, two-dimensional nanosheets, and three-dimensional structures according to the geometric structures. For instance, a LLZTO/PEO CSSEs was prepared by dispersing a zero-dimensional LLZTO powder into acetonitrile solution of PEO/LiTFSI. The room-temperature ion conductivity and electrochemical stability window of LLZTO/PEO CSSEs are 4.76×10^-4 S/cm and 4.75 V, respectively. The multi-mixing CSSE membrane consisting of LLZTO, PEO, PVDF-HFP, and LiTFSI has a high ionic conductivity of 1.05×10^-4 S/cm at 35 ℃, an electrochemical window of 5.2 V, and a high Li⁺ transference number of 0.52 at 60 ℃. A three-dimensional PVDF/LLZO/LiClO₄ CSSEs was obtained by adding 3D coral-like LLZO nanofiller into PVDF/LiClO₄. This CSSE membrane structured 3D interconnected framework has an enhanced ionic conductivity of 1.51×10^-4 S/cm at room temperature. The assembled battery delivers a capacity retention of 95.2% after 200 cycles at 1 C. The NASICON-type Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) and Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) ceramics as active fillers were added into PEO and PVDF-HFP polymers. A PVDF-HFP/LiTFSI CSSE containing 50% (in mass fraction) LAGP displays the maximum ionic conductivity of 9.2×10^-4 to 9.6×10^-4 S/cm at room temperature. After 50 cycles, the cell with PVDF-HFP/50% LAGP/LiTFSI CSSE remains 141.3 mA·h/g and a capacity retention rate of 89.5%.

Besides, sulfide fillers were investigated. However, sulfides are instability in air because it intrinsically tends to react with moisture to generate toxic H₂S gas. The CSSEs prepared with sulfide fillers improve asulfide stability and offer a high ion conductivity. For instance, adding sulfide active filler Li₁₀GeP₂S₁₂ (LGPS) to PEO polymer can prepare a PEO/LGPS/LiTFSI CSSE membrane with a stability in air. The CSSE has an ionic conductivity of 1.18×10^-4 S/cm at room temperature. After 150 cycles at 0.5 C, the cells using PEO/LGPS/LiTFSI as a membrane demonstrates superior capacity retention and rate performance.

To meet high-voltage cathodes and lithium metal, CSSEs with bi-layered or multi-layered structures maximize the synergistic effect of each layer without or withless sacrificing their properties, particularly for adjustable interphase. A bi-layer structure used Li_6.4La₃Zr₂Al_0.2O₁₂/PEO/LiTFSI and I₂/PEO/LiTFSI CSSE layers to contact with cathode and anode, respectively. After 500 cycles at 0.2 C, the LFP||Li cell maintains a specific capacity of 146.20 mA·h/g. A sandwich structure CSSE with PAN/PVDF-80% (in mass) LLTO/PEO was prepared by a casting method, having an ionic conductivity of 2.81×10^-4 S/cm and an electrochemical window of 4.92 V. The assembled battery delivers the Coulomb efficiency of 99.2% and a capacity retention rate of 88% at 0.5 C after 500 cycles.

The mechanism of ion transport in CSSEs has not yet clarified due to itscomplexity. The current well-known ion transport pathways in CSSEs include polymer matrix, inorganic active fillers and interfacial regions between polymer matrix and active fillers. Among them, the ion-transport pathway at the interfaces is relatively complex, and more efforts are needed to reveal the mechanism.

Attapulgite is a rod like silicate clay minerals with a 2∶1 type chain layered nanostructure, and the length of rod crystal is 0.5-5.0 μm. It is a non-renewable natural nanomaterial. The layered crystal structure of the attapulgite chain endows it with special physical and chemical properties, including adsorption, colloidal, and cation exchange properties. Attapulgite is widely used in agriculture, environmental protection, chemical industry, and other fields due to its superior properties. The breakthrough in key common technologies for the dissociation of crystal beams in palygorskite rods enables the expansion of palygorskite from conventional applications to high-tech applications. Attapulgite as a non-toxic natural mineral material has good biocompatibility, abundant reserves, and low price. It has an enormous application potential in the field of high value-added biopharmaceuticals. This review summarized recent research work on the application, the structure and properties of attapulgite.

The first part summarized the research progress of the application of attapulgite in the field of biological antibacterial, elaborated on the possible antibacterial mechanisms of attapulgite composite antibacterial materials, compared the preparation methods and antibacterial properties of different attapulgite based composite antibacterial materials, and gave that one of the research hotspots for attapulgite based composite antibacterial materials is to explore a simple and green preparation method.

The second part summarized the application of attapulgite in the field of feed additives, represented the preparation of three different attapulgite based feed additives and their respective advantages and disadvantages, and pointed out that the relevant products are used in production practice, and listed some typical production process diagrams of the products.

The third part represented the application of palygorskite in drug carriers. Attapulgite based drug carriers are mainly in the form of hydrogels and nanofibers. At present, there is no research on the application of attapulgite based drug carriers in vivo. The main reason is that the safety of palygorskite in vivo is unknown, and it is also stable, making it difficult to enter the blood and urinary circulation system as a drug carrier. However, the prepared attapulgite sustained-release tablets can be discharged through the digestive system and have great application prospects.

The fourth part represented the application of attapulgite in composite scaffold materials. Although attapulgite based composite scaffold materials have a good osteogenic induction in vitro, their osteogenic induction in vivo is still unclear, and the mechanism of osteogenic induction in vitro is still unclear.

The fifth part summarized the application of attapulgite in wound healing. Attapulgite based wound dressings have a good usability. Mixed dimensional attapulgite seems to have better usage effects and is expected to become a novel generation of hemostatic materials.

Bi₂Te₃ based alloys have attracted considerable attention in low-temperature thermoelectric materials due to their superior electrical transport properties and low thermal conductivity. However, the conversion efficiency of thermoelectric power generation or refrigeration devices made of Bi₂Te₃-based alloys is still low. It is thus crucial to further improve the thermoelectric figure of merit zT of Bi₂Te₃ based materials. There are some correlations between lattice thermal conductivity and electrical performance parameter. Reducing the lattice thermal conductivity by phonon engineering becomes an important method to increase zT without deteriorating the electrical performance. This review summarized the main research progress in recent years to optimize the thermoelectric properties of Bi₂Te₃ based materials by phonon engineering, such as nano-modification, superlattice structure, nanocomposing, doping and adding dislocation arrays. The effect of the optimization method on the specific heat capacity, phonon group velocity and phonon mean free path was discussed. The specific heat capacity, phonon group velocity or phonon mean free path of Bi₂Te₃ based materials can be significantly reduced by the optimization methods. As a result, the lattice thermal conductivity of Bi₂Te₃ based materials is significantly reduced, leading to a significant increase in the thermoelectric properties.

Nano-modification: The interface density is increased via low dimensionalization and grain refinement, resulting in an enhanced scattering of low-frequency phonons, reduced phonon mean free path and phonon group velocity, significantly reducing the lattice thermal conductivity. Nowadays, the grain size and morphology of Bi₂Te₃-based alloys can be precisely controlled by mechanical milling, MBE method, hydrothermal method, chemical vapour deposition and wet chemical method. Bi₂Te₃ nanostructures with a ultra-low grain size can be prepared. However, heat conduction cannot be completely prevented even at rather small sizes due to the incomplete suppression of low-frequency phonons. Therefore, it is difficult to improve zT by a single low-dimensionalisation and grain refinement method. The specific surface area can be increased either by combining the phases of different nanostructures to form a heterogeneous interface or by introducing special nanostructures such as twins and nanopores, which can strongly scatter the low-frequency phonons caused by lattice mismatch and lattice vibration, and further reduce the lattice thermal conductivity.

Bi₂Te₃-based superlattice structure: Furthermore, in the microscopic and mesoscopic scales, the superlattice structure generated by artificially controlling the ordered arrangement of atomic layers of Bi₂Te₃-based materials is considered as the optimum candidate material to achieve the 'phonon glass-electron crystal' thermoelectric material standard. Especifically, the quantum well structure in the thin film superlattice produces an intense boundary scattering effect and a quantum confinement effect on phonons, resulting in a decrease in the mean free path and group velocity of phonons, greatly reducing the thermal conductivity of Bi₂Te₃-based thermoelectric materials. The bulk superlattice structure of the Bi₂Te₃-based alloy relies on its complex crystal structure and acousto-optic coupling effect, causing a low cut-off frequency of phonon mode and an intense phonon resonance scattering, and resulting in a low intrinsic thermal conductivity. In addition, the low phonon group velocity caused by chemical bond softening and lattice anharmonicity is also a reason for the low intrinsic thermal conductivity of the bulk superlattice structure of Bi₂Te₃-based alloy.

Nanocomposites, doping modification and dislocation arrays: Nanocomposite and doping modification are the main approaches to improve the thermoelectric properties of Bi₂Te₃-based materials. In the nanocomposite process, the nanoparticles dispersed in the thermoelectric material do not enter the matrix lattice, but attach onto the surface of the matrix grain, forming a heterogeneous interface with the matrix. Also, introducing nanoparticles increases the grain boundary density, resulting in a further scattering of low frequency phonons. Doping modification is achieved by doping elements entering the Bi₂Te₃ lattice, replacing Bi site (or Te site) or entering the van der Waals gap for interstitial doping. This process can introduce multiple scattering centers such as grain boundaries, point defects, in-situ precipitates and dislocations into Bi₂Te₃-based alloy, enhancing a multi-scale scattering of phonons and effectively reducing the mean free path of phonons. Combined with the preparation process such as sintering, the dislocation array is increased, which leads to a higher scattering intensity of intermediate frequency phonons, further reducing the lattice thermal conductivity.

With the rapid growth of population and the development of industry, the lack of clean water resources becomes increasingly prominent. For the shortage of clean water resources, China as a country rich in seawater resources vigorously promotes seawater desalination technology, which has gradually developed into a strategic industry. Compared with the existing desalination technologies such as multi-effect distillation, multi-stage flash evaporation, reverse osmosis membrane, electrodialysis and so on, the desalination technology based on the principle of solar photothermal conversion has unparalleled advantages, i.e., environmental-friendly, high efficiency and low cost. Solar-driven steam generation (SSG) could be widely applied in seawater desalination, sewage treatment and other fields, which is of great significance in acquiring pure water and solving the problem of water resource shortage.

Ultra-high solar steam conversion efficiency could be achieved by increasing photothermal conversion efficiency, water transfer rate and heat management of the SSG system. In recent years, the evaporation models underwent a gradual transition from using photothermal particles dispersed in volume water to interface water evaporation with porous insulation layer or 1D or 2D water transport channels to the hydrophilic gel evaporation structure. It is reported that TiN hyperbranched nanowires have a better solar light absorption and a higher specific surface area to evaporate water rather than TiN nanoparticles and nanotubes. Its solar water evaporation rate and solar thermal conversion efficiency are 1.525 2 kg·m^-2·h^-1 and 94.01%, respectively, under 1 kW·m^-2 simulated solar irradiation. Zhu et al. demonstrated that a carbon foam with a three-dimensional interconnected porous structure enables a sufficient diffusion of vapor with a convective flow and realizes an evaporation rate of 10.9 kg·m^-2·h^-1. Solar-driven steam-electricity system expands the functionary of SSG, providing an innovative pattern for the electricity supply for tiny electronic devices, flexible wearable devices and remote area. Solar-driven steam-electricity system is mainly divided into integrating electricity generation module and self-powered electricity generation module. In SSG and PV cell integration modules, Xu et al. experimentally demonstrated that a prototype hybrid tandem solar device with WTIL can generate electricity with a power output of 204 W·m^-2 and purify water at 0.80 kg·m^-2·h^-1 under 1-sun illumination. Deng et al. realized that the evaporation rate of the prepared TEC in seawater electrolyte is 1.1 kg·m^-2·h^-1, and the solar vapor conversion efficiency of the TEC is 60% with a peak output power of 0.5 mW·m^-2. In self-powered electricity generation modules, Guo et al. presented a device prototype for enhanced power generation from ambient humidity, the device to ambient humidity can produce voltages of 0.78 V and a current of 7.5 μA, both of which can be sustained for more than 10 d. In this review, we summarized recent research work on the solar-driven steam-electricity system, and analyzef the advantages and disadvantages of different electricity generation modules.

The catalytic conversion of greenhouse gases, such as carbon dioxide and methane, into high-value-added chemicals/fuels (i.e., formic acid, methanol, ethylene, etc.) is recognized as a cost-effective tactic for achieving the "dual-carbon" purpose. It provides an alternative to fossil fuels, and also offers novel approaches to environmental dilemmas such as global warming. Catalysts with an extensive specific surface area and plentiful surface active sites are capable of absorbing and aligning reactant molecules, including CO₂ and methane, in an orientated manner. This reduces the energy required to activate the reaction, thereby enhancing the efficiency and selectivity of CO₂ reduction and methane activation reactions. Developing novel catalysts with low cost, high catalytic activity, good long-term stability, and high product selectivity becomes popular to improve the efficiency of energy catalytic conversion. Perovskite composite oxides are a promising nanomaterial with superior redox performance, high stability, facile structural regulation, and rich active sites, offering some advantages for developed catalysts. For the advantageous properties of perovskite composite oxides in catalytic reactions, it is crucial to comprehensively investigate the catalytic mechanism of these oxides in CO₂ reduction and methane activation, promote the development of high-performance perovskite composite oxide catalysts, and accelerate global efforts towards achieving carbon peak and carbon neutrality. Therefore, there is an urgent need to summarize the research progress on perovskite composite oxides for CO₂ reduction and methane activation. This review represented the thermocatalytic, photocatalytic, electrocatalytic, and synergistic catalysis applications of perovskite composite oxides, with summarizing their catalytic performance in CO₂ reduction and methane activation.

Perovskite composite oxide catalysts have a potential in facilitating thermally catalyzed CO₂ reduction and methane activation reactions. In particular, some rare-earth-based perovskite composite oxide catalysts serve a crucial function in this regard. The morphology, compositional structure, and surface adsorption properties of perovskite composite oxide catalysts are modulated via optimizing the preparation method and doping/substitution of metal elements. This leads to an increase in the oxygen vacancies and active sites of the catalysts, thereby improving their catalytic performance in thermocatalytic reactions. Compared to the photocatalytic and electrocatalytic materials, thermaocatalytic material yields a faster reaction rate, but the catalyst is susceptible to coking and carbon deposition at elevated temperatures. In addition, perovskite composite oxide catalysts demonstrate the superior effectiveness in the processes of photocatalytic reduction of CO₂ and activation of methane. The energy band structure of the perovskite composite oxide photocatalyst are adjusted via doping with transition and rare-earth metals, optimizing morphology, regulating oxygen vacancy, loading cocatalysts, and constructing heterogeneous structures, etc.. This can broaden the light absorption range, reduce the reaction activation energy, promote the photogenerated carrier separation, inhibite the electron-hole pair recombination, and improve the reactant adsorption on the photocatalyst surface. This leads to the improved production rate, yield, and selectivity of the product. Photocatalysis offers environmentally friendly and controllable processes, yet it is limited due to its low reaction rate and selectivity for product formation. Also, perovskite composite oxide catalysts demonstrate a significant potential for electrocatalytic CO₂ reduction and methane activation reactions. Perovskite composite oxides constitute a commendable class of electrocatalytic cathode materials showcasing exceptional ionic conductivity and redox properties. Scientists further enhance the conductivity of the materials by elemental doping at A/B sites and constructing oxygen vacancy to facilitate electron transfer, thereby improving the electrocatalytic performance of perovskite composite oxides. The electrocatalytic reaction offers some advantages like efficiency, cleanliness, and high product selectivity. Nonetheless, the reaction performance is extensively impacted underits reaction conditions (i.e., electrodes, electrolyte solution, etc.). In recent years, the combination of two or more catalytic technologies through synergistic catalysis has attracted much attention alongside the progress of catalytic research. Synergistic catalysis incorporates the benefits of individual catalytic technologies, while overcoming their inherent drawbacks, leading to the more effective and stable catalytic reactions. Synergistic catalytic techniques also allow catalysts that are not suitable for an individual catalytic reaction to be applied to a synergistic catalytic reaction under appropriate imposed conditions. Currently, perovskite composite oxide catalysts are still in their infancy for synergistic catalysis reactions, and researchers have not thoroughly examined the reaction conditions, basic principles, and interactions of various catalytic methods involved in synergistic catalysis reactions yet. The further exploration is required to generate more stable and efficient catalysts for synergistic catalysis reactions.

Hydrophobic modification of cement-based coating is beneficial to improving its protective effect, but it leads to poor dispersion of coating, weakening of physical properties and durability of coating. In this paper, a highly stable/hydrophobic modified polyacrylate emulsion was prepared by using hydroxy-containing polydimethylsiloxane (PDMS) as a second oil phase, and a high durability polymer cement-based protective coating was further constructed. The modified emulsions with good stability and hydrophobicity can be obtained by matching the molecular weight and dosage of PDMS and emulsifying the shear rate. Little stratification occurs after 30 d, the contact angle of latex film is increased by 24.9%, and the water absorption is decreased by 28.94%. The prepared polymer cement-based coating has superior mechanical properties, hydrophobicity, UV aging resistance, seawater and alkali immersion resistance, and the chloride ion permeability coefficient is only 0.193×10^-6 mm²/s. In addition, the modification mechanism of emulsion and the durability enhancement mechanism of coating were also analyzed.

In marine environment, complex environmental factors such as temperature and dry-wet cycles accelerate the transmission process of chloride in concrete, thus affecting the durability of concrete structures. It is of great significance to strengthen the research on the durability evaluation of concrete in this special corrosive environment. At present, a single index (i.e., chloride diffusion coefficient) is usually used to quantify the influence of environmental factors on the durability of concrete, which cannot comprehensively reflect the influence of environmental factors on the chloride ion transport process. Based on the Fick second law, we derived an analytical solution of the total amount of chloride ions entering the concrete from the diffusion flux, as the accumulated content of chloride. For the cumulative content of chloride, the quantitative index 'l value' of concrete chloride permeability was established, and then the comprehensive evaluation method of concrete durability was constructed when the two typical marine environmental factors of temperature and dry-wet cycle were concerned. The influence of environmental factors such as temperature and dry-wet cycle on the l value of concrete was analyzed. A linear relationship between the 28-d apparent chloride diffusion coefficient D₂₈ and the maximum monthly average temperature T_max and a linear relationship between the age coefficient m and the annual temperature difference ΔT_y were revealed. Subsequently, a simplified calculation formula for the quantitative index l value of concrete chloride ion permeability with respect of effects like dry-wet cycle and temperature was proposed. This formula is suitable for evaluating the influence of complex environmental factors (i.e., temperature and dry-wet cycle) on the concrete chloride permeability.

Ocean is a largest carbon reservoir in the Earth, and the total production of marine shellfish in China is huge. Most of shellfish only utilizes their edible value, and shells are randomly stacked or buried as a solid waste. To improve the utilization rate of shellfish waste, the effect of NaAlO₂ on the hydration process, solid-liquid phase composition, pore structure and mechanical property of the shell powder-calcium aluminate cementitious system was investigated. The results show that NaAlO₂ enables accelerating the hydration process, shortening the setting time, and slightly improving the compactness and mechanical properties of the hardened matrix. NaAlO₂ affects the solid-liquid phase composition. Adding NaAlO₂ increases the alkalinity of the pore solution and improves the reactivity of CaCO₃, leading such a cementitious system to the formation of a stable phase (i.e., monocarboaluminate (C₄AcH₁₁)) with a reduced amount of the unstable phase (i.e., calcium aluminate hydrate (CAH₁₀)). The samples with 3.75‰ and 5.00‰ of NaAlO₂ produce 13.0% and 13.6% of C₄AcH₁₁, respectively, and no CAH₁₀ phase occurs after cured for 28 d. The crystallite size of the microcrystalline AH₃ phase grows, which compromises the cementitious property because NaAlO₂ increases the alkalinity. The excessive NaAlO₂ leads to a decreased mechanical property. Mussel shell-based carbonaluminate cementitions materials hold promise in marine civil engineering construction.