Magnesium phosphate cement (MPC) has attracted recent attention due to its rapid setting, high early strength, and excellent bonding performance, making it a promising material for rapid repair and strengthening of concrete structures. In composite repair systems, the interfacial behavior between MPC-based repair materials and Portland cement concrete (PCC) substrates plays a decisive role in the overall structural performance, durability, and failure mode. However, the interface between MPC and PCC is often characterized by microstructural heterogeneity, the mismatch of mechanical properties, and the presence of initial defects, significantly reducing interfacial fracture resistance, especially under complex loading conditions. Nano-modification is widely recognized as an effective strategy to enhance the mechanical properties and microstructure of cement-based materials. Nanoparticles of silica (NS) can accelerate hydration, refine pore structure, and improve interfacial bonding through physical filling and chemical coupling effects due to its extremely high specific surface area and high pozzolanic reactivity. Despite extensive studies on the mechanical performance and modification mechanisms of NS-modified MPC (NS-MPC), systematic investigations on the interfacial fracture behavior between NS-MPC and PCC under mixed-mode loading conditions remain limited. It is thus essential to clarify the interfacial fracture mechanism and fracture resistance of NS-MPC/PCC systems under different fracture modes. In this study, asymmetric semi-circular bending beam (ASCB) specimens were employed to comprehensively investigate the mixed-mode interfacial fracture behavior of NS-MPC/PCC interface. The combined effects of initial crack length and fracture mix on the interfacial bonding strength, fracture parameters and nano-modification were investigated.

NS-MPC was prepared with dead-burned magnesia (M), potassium dihydrogen phosphate (P), NS, borax retarder (Bo), and deionized water (W). An orthogonal experimental design L9(3⁴) was adopted to optimize the mix proportion, considering four factors (i.e., Mg/P mass ratio, water-to-cement ratio (W/C), borax content (Bo/M), and NS content (NS/C)). The compressive and flexural strengths at 3 h and 1 d were selected as evaluation indices. According to the standard GB/T 17671—2021, the specimens NS-MPC of 40 mm × 40 mm × 160 mm were prepared to conduct flexural and compressive strength tests. Based on the results of orthogonal analysis, the optimal mix proportion of NS-MPC was determined and further compared with conventional MPC at different curing ages.

The interfacial fracture performance was evaluated by ASCB test, and the pure mode Ⅰ, pure mode Ⅱ and mixed mode Ⅰ/Ⅱfracture were achieved via adjusting the support position. Different crack length ratios (i.e., a/R=0.1, 0.2, and 0.3) and mixed mode parameters were selected to systematically investigate the mechanical response of the NS-MPC/PCC interface under different fracture modes. The geometric factors of the ASCB specimens were calibrated by the finite element method to achieve the quantitative analysis of the interfacial fracture parameters.

The microstructure and elemental composition of the interface were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). After the samples were dried at a low temperature to terminate hydration and treated for conductivity, the interface morphology and the distribution characteristics of hydration products were analyzed under high vacuum conditions.

Based on the results of orthogonal experimental design, the mechanical properties of NS-MPC are systematically investigated. The optimal mix is determined to be M/P of 2.5/1, W/C of 0.14, Bo/M of 0.08, and NS/C of 0.04. NS-MPC exhibits significantly enhanced mechanical properties. The compressive and flexural strengths at 3 h increase to 47.3 MPa and 7.3 MPa, respectively, and increase to 76.5 MPa and 8.6 MPa at 1 d. From 7 to 28 d, the compressive strength increases slowly from 81.3 MPa to 88.7 MPa, and the flexural strength increases from 9.1 MPa to 9.4 MPa, which still maintains a high value. The flexural-to-compressive strength ratio of NS-MPC is 9%, which is higher than that of pure MPC (i.e., 5%). It is indicated that NS can improve the strength and the toughness.

The interface bonding strength of NS-MPC/PCC decreases with the increase of a/R. This is consistent across all the fracture modes (i.e., pure mode Ⅰ, pure mode Ⅱ, and mixed mode Ⅰ/Ⅱ). The interface bonding strength corresponding to pure mode II fracture is the maximum value, while that of pure mode I is the minimum value. The force-displacement response shows that the interface fracture process is dominated by brittle failure. The increase of crack length significantly reduces the peak load-bearing capacity and deformation ability, and promotes the crack to expand dominantly from the interface to bend and branch, especially at larger a/R rates.

The fracture parameter analysis indicates that the interface fracture toughness is highly sensitive to the fracture modes and a/R. As the mix of fracture increases, the effective fracture toughness shows an overall downward trend. The most unfavorable fracture condition occurs in the mixed mode I/II fracture, where the interface crack resistance is the lowest. Pure mode I fracture causes a damage to the interface, and the larger crack length significantly weakens the crack resistance of the pure mode II interface.

The microscopic analysis reveals that the interface of approximately 20 μm wide is formed between NS-MPC and PCC. The hydration products K-struvite can occur in the interface. Moreover, elements Mg, P, and Si appear certain degrees of infiltration and enrichment on the both sides of the interface. The addition of NS effectively improves the interface reaction activity and microstructure densification.

NS-MPC demonstrated significantly enhanced compressive and flexural strength, indicating that NS could effectively promote the hydration reaction and structural densification. The results of the ASCB test indicated that the bonding strength of the NS-MPC/PCC interface decreased as a/R increased. The interface fracture process showed a significant nonlinear characteristic. The pure mode I fracture was the most unfavorable. The mixed fracture analysis revealed the nonlinear relationship between the effective fracture toughness and the mixity of fracture. The SEM images and EDS spectra further confirmed that NS enhanced the chemical bonding and crack resistance at the interface via promoting the formation and filling of Si-P-Mg composite hydration products in the interface.

Proton-conducting solid oxide fuel cells (H-SOFCs) require highly active oxygen electrodes to enhance their electrochemical performance and stability at intermediate and low temperatures. However, conventional oxygen electrode materials often suffer from high thermal expansion coefficients and insufficient catalytic activity at reduced temperatures, making them unsuitable for H-SOFC applications. Misfit-layered oxides (MLOs) can offer a promising solution due to their unique structural and catalytic properties. In this study, a series of Na_0.15X_2.85Co₄O_9-δ (X=Ca, Sr, Ba; abbreviated as NCC, NSC, and NBC) materials were synthesized by a glycine-nitrate combustion method. These materials possess a misfit-layered structure ([X₂CoO_3-δ] and [CoO_2-δ] layers), which reduces their thermal expansion coefficients and enhances the catalytic activity of oxygen electrodes at intermediate and low temperatures. Among the Na_0.15X_2.85Co₄O_9-δ materials, NSC exhibits the optimum performance (i.e., an electrical conductivity of 57.1 S·cm^-1 at 700 ℃ in 5% (in volume fraction) H₂O atmosphere, and an area-specific resistance (ASR) of 0.19 Ω·cm² at 650 ℃ in an NSC|BZCYYb (BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ)|NSC symmetric cell, with only a ~2% increase in ASR after 100 h at 600 ℃). In a full-cell test with NSC|BZCYYb|Ni-BZCYYb, the oxygen electrode achieves power densities of 1273 mW·cm^-2 and 362 mW·cm^-2 at 650 ℃ and 500 ℃, respectively, and demonstrates a stable operation for 165 h at a constant current density of 0.54 A·cm^-2 at 600 ℃. This work demonstrates that the misfit-layered Na_0.15Sr_2.85Co₄O_9-δ material has a significant promising application in H-SOFCs.

In this study, three materials of the misfit-layered Na_0.15X_2.85Co₄O_9-δ (NXC, X=Ca, Sr, Ba; abbreviated as NCC, NSC, NBC) system were synthesized by a glycine-nitrate combustion method. These materials featured an alternating stacking structure composed of [X₂CoO_3-δ] and [CoO_2-δ] layers. The NXC series electrode materials were obtained via calcination in a muffle furnace at 800 ℃ for 2 h, followed by grinding. The intrinsic properties of the materials (i.e., electrical conductivity and thermal expansion coefficient) were characterized. Electrode slurries were prepared via grinding the materials, which were then screen-printed onto BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) electrolyte pellets to fabricate NXC|BZCYYb|NXC symmetric cells. These symmetric cells underwent temperature sensitivity, humidity sensitivity, and stability tests. The material with the optimal comprehensive performance was selected to construct NXC|BZCYYb|Ni-BZCYYb full cells. The full cells were characterized by current density-voltage measurement, electrochemical impedance spectroscopy (EIS) at 650-500 ℃, and relaxation time (DRT) analysis.

Among the three materials, NCC and NSC both exhibit well-formed phases, whereas NBC produces a significant amount of the secondary phase BaCoO_3-δ. The thermal expansion coefficients (TECs) of NCC and NSC are relatively low, while that of NBC is notably higher due to the high TEC of the secondary phase. In terms of electrical conductivity, NSC demonstrates the optimum performance among the three materials, achieving 40.8 S·cm^-1 at 500 ℃ in dry air, which is significantly superior to those of NCC and NBC. At 650 ℃, the polarization resistances (R_p) of NCC and NSC both are 0.190 Ω·cm², while NBC exhibits a higher R_p of 0.252 Ω·cm², indicating that Ca- and Sr-doped electrodes possess comparable charge transfer capabilities at elevated temperatures, whereas the Ba-doped material performs slightly worse. Also, NSC displays a superior performance in both humidity sensitivity and stability tests. Based on the analysis above, NSC in the NXC series with the maximum conductivity, catalytic activity, and stability is selected as an oxygen electrode for the NSC|BZCYYb|Ni-BZCYYb full cell for subsequent testing. NSC exhibits excellent performance and stability, delivering power densities of 1273, 1095, 704, 362, 170 mW·cm^-2 and 91 mW·cm^-2 at 650-400 ℃. Moreover, it demonstrates a stable operation for 165 h at an applied current density of 0.54 A·cm^-2, confirming its potential as an oxygen electrode for H-SOFCs.

This study synthesized a series of misfit-layered Na_0.15X_2.85Co₄O_9-δ (NXC, X=Ca, Sr, Ba; abbreviated as NCC, NSC, and NBC) oxygen electrode materials by a glycine-nitrate combustion method. The influences of elements Ca, Sr, and Ba on the crystal structure and electrochemical properties were systematically investigated. Among the synthesized materials, Na_0.15Sr_2.85Co₄O_9-δ (NSC) demonstrated optimal electrochemical performance and stability. It exhibited an electrical conductivity of 57.1 S·cm^-1 at 700 ℃ in a 5% H₂O+95% air atmosphere. The NSC symmetric cell showed the lowest area-specific polarization resistances (ASR) of 0.190, 0.323, 0.590 Ω·cm², and 0.911 Ω·cm² at 650-500 ℃, along with excellent long-term stability. These superior characteristics were further confirmed in NSC|BZCYYb|Ni-BZCYYb full-cell tests, achieving high power densities of 1273, 1095, 704, 362 mW·cm^-2 at 650-500 ℃, respectively. Moreover, the cell maintained stable operation for 165 h at an applied current density of 0.54 A·cm^-2, demonstrating a remarkable stability. These results indicated that the triple-conducting (H⁺/O^2-/e^-) misfit-layered NSC material could be a highly promising oxygen electrode candidate for intermediate-to-low temperature solid oxide cells.

Terahertz (THz) waves, typically spanning the frequency range from 0.1 to 10 THz, possess unique characteristics such as low photon energy, broad bandwidth, and strong penetration through nonpolar materials, enabling important applications in wireless communication, biomedical sensing, and nondestructive evaluation. Efficient manipulation of the amplitude, frequency, and phase of THz radiation is essential for the development of high-performance functional devices. Metasurfaces composed of subwavelength artificial meta-atoms provide a versatile platform for THz wavefront engineering through tailored electromagnetic responses. However, most reported THz metasurfaces operate in the linear regime and rely on propagation or geometric phase, which limits their functionality to the fundamental frequency and prevents the integration of frequency conversion and wavefront control. Second-harmonic generation (SHG) offers an effective approach for extending the accessible THz spectral range. Conventional nonlinear crystals, however, suffer from low nonlinear efficiency and stringent phase-matching requirements in this frequency region, which restrict device miniaturization and integration. Resonant artificial microstructures in semiconductors provide an alternative nonlinear mechanism through strong local electromagnetic field enhancement, where the Lorentz-force-driven nonlinear current gives rise to an effective second-order response. Nevertheless, the phase of nonlinear radiation remains difficult to control independently of the radiation amplitude. Therefore, establishing a deterministic relationship between the resonance phase and the nonlinear radiation phase is critical for nonlinear wavefront engineering. In this work, a GaAs-based metasurface is designed to correlate the resonance phase at the fundamental frequency with the phase of the second-harmonic radiation, enabling phase-engineered nonlinear wavefront construction.

The metasurface consists of gold split-ring resonators patterned on a silicon-doped n-type GaAs epitaxial layer grown on a semi-insulating GaAs substrate. Under normal incidence of an x-polarized THz wave, the resonant current in the metallic ring generates a localized magnetic field perpendicular to the surface and a strongly enhanced electric field in the split gap. The electric field drives free carriers in the n-GaAs layer, while the localized magnetic field exerts a Lorentz force on the moving carriers, resulting in a nonlinear current oscillating at twice the fundamental frequency. Three-dimensional full-wave simulations based on the finite-element method were carried out to optimize the structural parameters and analyze both the linear resonance and nonlinear time-domain response. An anisotropic conductivity tensor was introduced to describe the magneto-electric coupling induced by the Lorentz force. Four meta-atoms with equally spaced resonance phases were designed, and an additional π phase shift was obtained by rotating the structures by 180°, resulting in eight discrete nonlinear phase states covering the full 0-2π range. The samples were fabricated using metal-organic chemical vapor deposition, photolithography, magnetron sputtering, and lift-off processes. The nonlinear response was characterized using a home-built strong-field terahertz time-domain spectroscopy (THz-TDS) system, in which the second-harmonic signal was extracted by spectral filtering and detected via electro-optic sampling.

Frequency-domain simulations show that all metasurface structures exhibit pronounced resonances near 0.8 THz, ensuring that the nonlinear phase comparison is performed under nearly identical linear response conditions. At the resonance frequency, strong local electric and magnetic field enhancements are observed, providing the physical origin for the Lorentz-force-driven nonlinear current. Time-domain simulations and experimental measurements confirm the generation of a cross-polarized second-harmonic signal at 1.6 THz. The four designed meta-atoms provide a phase interval of 0.25π, and the corresponding rotated structures introduce an additional π phase shift, resulting in eight discrete nonlinear phase states with nearly uniform spacing over the entire 0-2π range. Although slight amplitude variations exist among different unit cells, the measured phase evolution follows the designed linear dependence, indicating that the nonlinear phase can be effectively modulated through the resonance phase. Based on the experimentally extracted complex responses of the meta-atoms, an equivalent surface current model was employed to reconstruct the far-field radiation. By arranging the discrete phase elements according to the helical phase distribution, the reconstructed far-field exhibits a doughnut-shaped intensity profile and a continuous azimuthal phase variation of 2πl, which are the characteristic features of vortex beams. These results confirm that the experimentally obtained nonlinear phase library enables nonlinear helical wavefront construction through ordered spatial arrangement of the meta-atoms.

A nonlinear metasurface capable of phase-engineered terahertz second-harmonic radiation has been designed and experimentally demonstrated. By correlating the resonance phase at the fundamental frequency with the phase of nonlinear radiation, eight discrete nonlinear phase states covering the full 0-2π range were achieved through meta-atom design and structural rotation. Based on the experimentally extracted complex responses, nonlinear helical wavefronts were reconstructed through ordered spatial arrangement of the phase elements. The results verify that nonlinear wavefront engineering can be achieved through the cooperative strategy of meta-atom design and ordered arrangement. This approach enables the integration of frequency conversion and wavefront shaping within a planar artificial structure and provides a feasible route for phase engineering in nonlinear THz metasurfaces as well as for integrated structured-light sources in THz communication, imaging, and information processing.

Hierarchical porous nitrogen-doped carbon-supported Mo₂C particle composite materials (Mo₂C@PCN-X) were constructed by an anti-solvent method and a subsequent in-situ pyrolysis process with ammonium molybdate tetrahydrate and ammonium citrate as precursors, and sodium chloride as a template. The nitrogen-doped carbon pore structure and Mo₂C loading in Mo₂C@PCN-X were regulated via adjusting the addition ratio of ammonium molybdate tetrahydrate. The results show that the number of hollow cavities in Mo₂C@PCN-X increases with the increase in the amount of ammonium molybdate tetrahydrate added, providing abundant storage space for lithium polysulfides (Li₂S_n, n=4-8) and restricting the diffusion of LiPS through physical interactions. Furthermore, the Mo₂C particles exhibit significant adsorption capacity and catalytic activity toward LiPS, accelerating the conversion of soluble Li₂S_n to solid-state Li₂S₂/Li₂S, thereby effectively suppressing the shuttle effect. The S@Mo₂C@PCN-1.5 cathode delivers a high reversible discharge capacity of 1207 mA·h·g^-1 at 0.1 C and maintains 517 mA·h·g^-1 at 1.0 C. After 200 cycles, this cathode demonstrates a low per-cycle decay rate of merely 0.1%, exhibiting superior cycling stability compared to pristine S@PCN.

15 g of sodium chloride was dissolved in 50 mL of deionized water. Afterwards, 1.5 g of ammonium molybdate tetrahydrate [(NH₄)₆Mo₇O₂₄·4H₂O] and 4.786 g of ammonium citrate (C₆H₁₇O₇N₃) were sequentially added to the solution, followed by continuous stirring until complete dissolution. The mixed solution above was rapidly poured into 400 mL of industrial ethanol and vigorously stirred for 5 min. After precipitation, the NaCl@C₆H₁₇O₇N₃-1.5 precursor was obtained by filtration and drying. Also, NaCl@C₆H₁₇O₇N₃-0, NaCl@C₆H₁₇O₇N₃-1.0, and NaCl@C₆H₁₇O₇N₃-2.0 precursors were prepared via varying the addition amount of ammonium molybdate tetrahydrate (0, 1 g, and 2 g), respectively, based on the above procedure. The NaCl@C₆H₁₇O₇N₃-X (X=0, 1.0, 1.5, and 2.0) precursors were heated in a tube furnace to 450 ℃ at a rate of 5 ℃·min^-1 under an Ar-H₂ (10%, in volume fraction) mixed atmosphere for 2 h, and then continuously heated to 800 ℃ at the same rate and held for another 2 h. After cooling to room temperature, NaCl-Mo₂C@PCN-X powders were obtained. The powders were washed for three times with deionized water to remove the NaCl template (with template recovery), and dried at 70 ℃ to obtain Mo₂C@PCN-X composites and PCN support materials. Mo₂C@PCN-X was mixed with sulfur powder at a mass ratio of 3∶7, ground uniformly with a small amount of ethanol and dried. The mixture was heated in a tube furnace to 155 ℃ at a rate of 5 ℃·min^-1, held for 12 h, and then further heated to 200 ℃ and held for 20 min to remove the excess sulfur on the surface of Mo₂C@PCN-X. After natural cooling, the S@Mo₂C@PCN-X composite cathode material was prepared. In addition, S@PCN composite cathode material was also prepared as a control sample using PCN as a substrate according to the procedure above.

The analysis of micro-morphologies of PCN and Mo₂C@PCN-X composites shows that the number of elongated pore structures increases from Mo₂C@PCN-1.0 to Mo₂C@PCN-1.5, but decreases significantly from Mo₂C@PCN-1.5 to Mo₂C@PCN-2.0 as the addition amount of (NH₄)₆Mo₇O₂₄·4H₂O increases, possibly due to the collapse of excessive pore structures. Abundant pore structures are beneficial for the storage and transport of electrolytes. Compared with other samples, Mo₂C@PCN-1.5 exhibits a larger specific surface area and pore structure, which can provide more internal voids for sulfur loading and inhibit the dissolution of Li₂S_n. Meanwhile, the smaller pore diameters can enhance the adsorption capacity of carbon materials for polysulfides. Compared with pure carbon materials, the specific surface area of composites with added ammonium molybdate tetrahydrate increases significantly. This is likely because during the precursor preparation process, ammonium molybdate tetrahydrate crystallizes on the sodium chloride template after adding ethanol. In the subsequent carbonization process, ammonium molybdate tetrahydrate crystals extract carbon from the carbon material to form molybdenum carbide. In this process, the vacancies of extracted carbon form micropores, and unreacted molybdate leaves some micropores after washing. These micropores provide a larger specific surface area for the carbon material. However, the specific surface area decreases with the increase in the addition amount of ammonium molybdate tetrahydrate, possibly because the excessive addition causes larger crystal grains to form on the sodium chloride template. The larger grains extract too much carbon during the reaction, leading to the collapse of generated micropores. The adsorption capacity of the support materials for polysulfides is intuitively determined by visual experiments and UV-VIS absorption spectroscopy. After adsorption by Mo₂C@PCN-1.5, the solution color significantly fades, and the absorption peak intensities of Li₂S₆ and Li₂S₄ decrease significantly, indicating that the Mo₂C@PCN-1.5 support material can strongly adsorb polysulfides. The results of symmetrical battery and deposition experiments demonstrate that Mo₂C@PCN-1.5 with appropriate molybdenum carbide catalysis exhibits better polysulfide conversion kinetics. The electrochemical performance analysis of full batteries confirms that Mo₂C@PCN-1.5 has superior cycling and rate performance, as well as high sulfur loading capacity. As a cathode substrate, Mo₂C@PCN-1.5 is more conducive to promoting the retention of polysulfides and the utilization of active materials.

In this work, a Mo₂C@PCN-X composite material with a hierarchical pore structure was constructed by a green and facile anti-solvent strategy. The results showed that the introduction of the precursor (NH₄)₆Mo₇O₂₄·4H₂O had a regulatory effect on the crystallization behavior of the NaCl template, inducing the carbon component in the Mo₂C@PCN-X composite to form a hierarchical pore structure with additional cavities, and the cavity density was positively correlated to the molybdenum source concentration. When Mo₂C@PCN-X was used as a host for LSB batteries, the three-dimensional interconnected pores of the PCN matrix could promote electrolyte infiltration and adsorb soluble Li₂S_n (n=4-8) through physical action. Moreover, the Mo₂C particles loaded on its surface could enhance the chemical adsorption of Li₂S_n by the Mo₂C@PCN-X host material through d-p orbital hybridization, while reducing the energy barrier for Li₂S deposition/decomposition. However, Mo₂C could agglomerate as the loading amount increased, reducing the specific surface area of the material. Therefore, under the same conditions, the S@Mo₂C@PCN-1.5 positive electrode exhibited the optimum reversible discharge capacity and capacity retention rate during cycling. The crystallization regulation mechanism could provide an idea for the controllable preparation of porous carbon-based composites. Future research could focus on reducing the particle size of Mo₂C through strategies such as surface functional modification, so as to provide a theoretical reference for the design of positive electrode materials for high-energy-density LSBs.

At present, large-scale homogeneous fabrication of multi-level ordered structures remains challenging, and it is difficult to maintain structural integrity and ordering consistency during mass production. Long-term service performance in high-salinity, oily and complex actual water environments lacks systematic verification, and problems such as salt deposition, pore blockage and interfacial fouling easily cause performance degradation. In addition, most porous ordered materials exhibit insufficient mechanical toughness against water scouring and dry-wet cyclic aging, while the mismatch between high evaporation capacity and limited condensation efficiency has become a prominent system-level constraint. Corresponding future research directions are proposed as, advancing the diversification of functional units to construct multi-mechanism photothermal libraries; innovating diversified ordered configurations by learning from natural bionic structures; realizing controllable assembly of third-level macroscopic ordered architectures. At the same time, future studies should address engineering bottlenecks such as scalable preparation, long-term stability and mechanical durability, and fully exploit photothermally induced kinetic enhancement effects to expand application scenarios in high-salinity wastewater, oily sewage, sludge dehydration and radioactive water purification. This review systematically clarifies the regulation mechanism of multi-level ordered structures in energy conversion and mass transport, summarizes existing challenges and future development paths, and provides solid theoretical support and rational design guidance for the development of high-efficiency, stable and engineerable photothermal evaporation materials and decentralized water resource allocation systems.

Centered on structural design of organic functional crystals and starting from the fundamentals of spin dynamics, this review represents key spin-relaxation mechanisms in organic materials, including SOC, exchange interaction, and HFI, and summarizes representative spin-related phenomena such as organic magnetic-field effects, spin transport, and organic magnetism. On this basis, this review highlights how crystal order, polymorphism, molecular packing, and conformational differences regulate spin behavior, and summarizes how isotope effects, atom substitution, and cooperative interactions in multicomponent systems affect spin effects. Meanwhile, this review introduces spin behaviors at heterojunction interfaces and the physical mechanisms of chirality-induced spin selectivity in chiral materials, together with commonly used strategies for constructing chiral structures. Effective regulation of spin effects in organic functional crystals relies on coordinated advances in structural design, chemical-composition control, and device-structure optimization. Future studies should place a greater emphasis on the quantitative characterization of structural parameters, discriminative verification of spin-relaxation mechanisms, and statistical reliability in multicomponent and interfacial systems. It is expected to realize efficient and stable organic spintronic devices via integrating molecular design, crystal engineering, interface modulation, and device-structure optimization, supporting flexible electronics and low-power information devices as well as emerging spin-functional integration.

Power splitters with low loss, compact footprint, and high stability are essential building blocks in modern on-chip photonic integrated systems for optical interconnection, signal routing, and dynamic optical power management. Conventional on-chip power splitters rely on phase matching and modal interference, and therefore usually suffer from splitting-ratio drift, increased loss, and enhanced crosstalk under bandwidth dispersion, fabrication errors, and bending-induced defects, making it difficult to maintain stable and consistent performance in large-scale integration. Photonic topological insulators (PTIs) exhibit remarkable advantages in suppressing backscattering, tolerating sharp bends, and maintaining robustness against defects due to their unique topologically protected edge-state transport, thus providing an effective route for the design of high-performance power splitters. However, the existing topological power splitters still regulate the splitting ratio via modifying geometric parameters, reconfiguring topological interfaces, or changing the coupling path length, so continuous dynamic tuning within a fixed structure remains difficult after fabrication, which restricts their application in reconfigurable integrated photonic systems. To overcome this limitation, this work was to propose a liquid-crystal-assisted topological power splitter based on coupled valley photonic crystal waveguides. From the perspective of functional units and ordered architectures, the device used petal-shaped VPC unit cells as the functional units and utilized zigzag topological interfaces together with backward-coupled waveguides as the ordered splitter architecture, thereby enabling continuously tunable power distribution through external-field-controlled liquid-crystal molecular reorientation, while preserving topological robustness.

A petal-shaped VPC unit cell was designed as a functional unit of the device. The spatial inversion symmetry was broken and a topolo gical bandgap was opened under transverse-magnetic (TM) polarization via changing the rotation angle from α of 0° to α of ±30°. Two topologically distinct domains (denoted as VPCA and VPCB) were then arranged into zigzag AB and BA interfaces, forming an ordered architecture that could support valley-locked edge states. On this basis, a topological power splitter consisting of two parallel topological waveguides and one rectangular coupling region was constructed. The coupling distance (d) was 4a and the coupling length (L) was 170a. A nematic liquid crystal (LC) was introduced into the air holes in the boundary waveguide and coupling regions. A line source polarized along the out-of-plane direction was placed at Port 1 to excite the edge state in WG1. The numerical simulations were conducted to calculate band structures, projected interface bands, transmission spectra, power-flow distributions, and electric-field distributions. In the numerical model, the liquid crystal was treated as a uniaxial anisotropic medium, and its optical response was described by an orientation-dependent permittivity tensor associated with director rotation in the XZ plane. The ordinary and extraordinary refractive indices were taken as n_o of 1.45 and n_e of 1.75, respectively. The LC-controlled section length was denoted by w, and its influence on the output power ratio was investigated at a fixed operating frequency of 193.4 THz. To evaluate topological robustness, six defects belonging to three representative defect types were introduced into the structure.

Based on this mechanism, effective backward coupling is realized between two adjacent topological waveguides in opposite propagation directions, and the simulated power-flow distribution shows a coupling loop consisting of forward transport in WG1, backward transport in WG2, and local vortex-mediated energy flow. To verify whether the coupling effect can be still preserved after introducing liquid crystal (LC), the transmission spectra of the two cases without and with LC filling in the boundary-waveguide and coupling regions are compared. The results show that effective coupling maintains in both cases, while the operating frequency range shifts after introducing LC. In the LC-filled case, nearly complete power transfer from WG1 to WG2 is achieved at 193.1-193.6 THz, and the total transmission efficiency reaches 93% as L=170a. When the LC orientation changes fromθ of 90° to θ of 0°, the coupling band shifts from 192.5-194.1 THz to 185.8-187.2 THz. At a fixed operating frequency of 193.4 THz, increasing the LC-controlled length w continuously reduces the effective coupling region, decreases the output power from WG2, and increases the transmitted power in WG1, thereby enabling continuously tunable power splitting in a fixed structure. In addition, the transmission spectra and output power ratios remain nearly unchanged under the representative defect types, defect numbers, and defect distributions, indicating that the proposed device maintains a good robustness against structural perturbations.

An LC-assisted topological power splitter based on coupled valley photonic crystal waveguides was proposed and numerically demonstrated from the perspective of functional-unit engineering and ordered-architecture design. The device could achieve robust edge-state transport, effective inter-waveguide coupling, and continuously tunable power distribution within a fixed structure via combining petal-shaped valley photonic crystal unit cells, zigzag topological interfaces, the ordered architecture of backward-coupled waveguides, and external-field-controlled molecular reorientation of nematic liquid crystal. The results showed that the proposed splitter could reach a total transmission efficiency of 93%, realize continuously tunable power splitting via adjusting the LC-controlled length, and maintain stable transmission and power-distribution performance under the representative defect conditions. This work could provide a feasible strategy for reconfigurable on-chip power routing, dynamic optical interconnection, and actively tunable topological photonic devices.

With the ever-increasing industrial demand for high energy density lithium-ion batteries, lithium-rich manganese-based layered oxide cathodes have attracted much attention due to their high specific capacity and low cost. However, their practical application is hindered by critical drawbacks including low initial Coulombic efficiency, irreversible oxygen release, and severe voltage fade. In this paper, bulk-engineered lithium-rich manganese-based layered oxides with a full concentration gradient were prepared by a room-temperature ammonia plasma interfacial modification strategy. In contrast to direct ammonia sintering, ammonia plasma modification could construct a stable spinel-amorphous composite nano-bifunctional motif ordered interface on the cathode surface that endowed fast Li⁺ transport kinetics. This bulk-surface functional motif ordering design concept could provide a novel and effective strategy for improving the overall electrochemical performance of lithium-rich oxide cathodes.

A precursor of cobalt-free full-concentration gradient twin-domain lithium-rich manganese-based layered oxide cathode material was synthesized by a co-precipitation method. After washing for impurity removal and vacuum drying, the precursor was uniformly mixed with 3% (in mole fraction) excess Li₂CO₃ for lithium supplementation and sintered to prepare the cobalt-free gradient lithium-rich manganese-based layered oxide cathode material (GLLOs). To investigate the modification effects of different treatment methods under ammonia atmosphere, the equal mass of GLLOs was subjected to direct ammonia sintering and ammonia plasma modification, respectively. The crystal structure, micro-morphology, electrochemical performance, ion transport kinetics, and transition metal valence state evolution of the materials before and after modification were determined by systematic characterizations including X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, electrochemical measurements, and kinetic analysis, respectively. Furthermore, the regulatory differences of ammonia treatment in different states on the performance of GLLOs and their intrinsic action mechanisms were revealed.

Two distinct ammonia-based treatments (i.e., direct ammonia sintering and ammonia plasma technology) have different impacts on the GLLOs' surface structure, valence variation, electrochemical performance, and stability. Direct ammonia sintering forms a rock salt-amorphous interface with more significant Mn valence reduction, improving initial efficiency and rate capability, while degrading cycling stability. Ammonia plasma constructs a stable spinel-amorphous interface facilitating Li⁺transport, with a milder Mn valence change, effectively stabilizing interfacial reactions and structure to remarkably enhance long-cycle performance and mitigate voltage decay.

The formation of rock salt and spinel phase functional units on GLLOs surface stems from ammonia-induced TM valence reduction, triggering Li leaching, oxygen vacancy formation, and TM migration to Li layers that drive layered-to-spinel/rock salt transformation. Direct ammonia sintering requires prolonged heating with limited ammonia decomposition, most nitrogen intermediates adsorb on the material surface, causing excessive TM migration and a rock salt-N-rich amorphous interface. Ammonia plasma enables a rapid ammonia decomposition into nitrogen intermediates for quick modification, forming a spinel-amorphous interface that enhances Li⁺ transport, inhibits oxygen loss, electrolyte corrosion, and stabilizes cycling via short-time treatment.

In this work, twin-domain lithium-rich manganese-based layered oxide cathodes with bulk full-concentration gradient were interface-modified via direct ammonia sintering and ammonia plasma treatment. The effect of interface modification method on the surface structure, electrochemical performance, TMs valence, kinetics, and stability was investigated. Ammonia nitridation could form a 2-3 nm N-containing amorphous interface, alleviating oxygen vacancies and enhancing oxygen redox reversibility. Ammonia plasma, operating at room temperature for minutes, could decompose into nitrogen active species under high electric field, constructing a spinel-amorphous composite interface favorable for Li⁺ transport. It could avoid Mn over-reduction and spinel-to-rock salt transformation, maintaining TMs reversibility. A robust bulk-surface synergistic stabilization system was established via integrating the bulk full concentration gradient twin-domain design with the surface composite nano-bifunctional motif ordering construction, remarkably boosting the electrochemical performance of the cathodes (i.e., the capacity retention of 81.5% after 900 cycles at 1 C, accompanied by a low voltage decay of only 0.21 mV/cycle). Controllable ammonia decomposition could facilitate a stable interface formation, offering a novel pathway to boost the comprehensive performance of LLOs.

This review introduces recent progress on the field of VEH based on ATIs. It respectively introduces VEH implemented in airborne sound and elastic wave systems based on topological edge states. VEH is realized due to the field enhancement effects induced by zero-dimensional localized states such as higher-order topological corner states and BICs. The multi-modal collaborative energy harvesting mechanisms oriente toward broadband and multi-frequency responses, further extending to high-throughput VEH based on large-area topological interface states. These studies demonstrate that ATI-based systems exhibit remarkable design flexibility, while maintaining both high energy conversion efficiency and strong robustness. The topological rainbow trapping effect is excited and the bandwidth limitations of conventional devices are overcome via introducing strategies such as structural modulation and multimodal coupling. On this basis, large-area topological waveguide states are used to substantially enhance energy transmission throughput, ultimately achieving comprehensive performance optimization in terms of high efficiency, broad bandwidth, and large capacity. However, the existing research on ATI-based VEH still has several limitations. First, the existing studies mainly focus on the medium- and high-frequency range, whereas low-frequency (≤100 Hz) VEH remains largely at the stage of theoretical exploration. The vibrations in everyday environments are predominantly low-frequency, a further research on low-frequency energy harvesting is still needed. Second, the evaluation of energy conversion efficiency in this field still lacks a unified standard framework. The electrical output metrics reported in previous studies, such as maximum voltage, output power, or amplification factor, are constrained via differing experimental testing benchmarks and therefore cannot be directly compared, which remains one of the key challenges to be addressed in the future VEH research. Meanwhile, most of the existing devices are still at the proof-of-concept stage and remain some distance away from practical engineering implementation and industrial application. Although topological states provide a relatively robust platform for energy transport, the existing studies on the stability of energy harvesting systems are still largely limited to structural defects and geometric perturbations. Systematic investigations into the effects of real environmental factors (i.e., temperature, humidity, load variation, and long-term operating conditions) on the performance of topological structures are still lacking.

As a highly promising filtering component for next-generation lightweight and miniaturized electronic circuits, supercapacitors have pursued performance breakthroughs centered on the synergistic optimization of ultrafast frequency response and high areal capacitance. Reviewing the evolution of electrode design for filtering supercapacitors reveals a paradigm shift from mere compositional engineering toward an ordering-driven paradigm guided by rational microstructural design. In this review, carbon-based filtering electrodes are systematically categorized according to structural dimensionality and spatial organization, including two-dimensional planar architectures, three-dimensional randomly macroporous frameworks, and highly vertically aligned configurations, thereby elucidating a pivotal role of structural ordering in governing charge-transport kinetics. In particular, three-dimensional ordered grid electrodes constructed from carbon tubes as functional building units are identified as an effective strategy to resolve the intrinsic trade-off between capacitance density and frequency response.

From the construction of an integrated electron/ion transport networks, the systematic structural evolution clearly demonstrates that the continuous improvement of filtering supercapacitor performance does not arise merely from the unbounded enlargement of specific surface area, but rather from achieving an optimal balance between ion transport accessibility (i.e., low-tortuosity pathways) and interfacial charge-storage density (i.e., highly active surfaces). Such carbon-tube-based, ordered interconnected networks extend the performance limits in terms of capacitance and frequency response, and provide a robust and reproducible structural framework for ultrafast charge transport, thereby effectively propelling the transition of supercapacitors from conventional energy-storage devices toward high-frequency filtering applications.

Despite the remarkable potential of functional unit ordering strategies, some substantial challenges remain in translating this concept toward deeper theoretical understanding and practical implementation. From a theoretical perspective, there is an urgent need to establish a universal, quantitative descriptor system for assessing the "degree of ordering" in electrode architectures. Specifically, key geometric descriptors should include tortuosity (i.e., quantifying deviation of ion transport pathways from ideal straight channels), connectivity parameters (i.e., lateral junction density), orientation distributions (i.e., reflecting alignment along the current collector normal), and spatial uniformity metrics. The quantitative relationships can be established between structural parameters and kinetic metrics such as phase angle, cutoff frequency, and characteristic time constants via integrating these descriptors with electrochemical impedance spectroscopy and multiphysics simulations. Such a framework linking geometric descriptors to dynamic electrochemical responses will enable a transition from empirical optimization toward digitally guided electrode design.

In terms of transport mechanism analysis, it is particularly important to develop methods capable of decoupling the respective contributions of electronic conduction and ionic diffusion. For instance, an experimental strategy involving "fixed structure-variable conductivity" can be employed, whereby the crystallinity of the material is selectively tuned, while maintaining identical three-dimensional architectures and mass loading, thereby isolating the influence of electronic transport on the frequency response. In parallel, finite element simulations based on realistic structural models with independent variation of electronic conductivity (σ_e) and ionic diffusivity (D_ion) can be used to perform sensitivity analyses and establish causal relationships among structure, transport parameters, and electrochemical performance. These methods provide a critical theoretical guidance for the targeted optimization of ordered electrode architectures.

At the structural design level, future efforts should focus on maintaining kinetic advantages under thick-electrode and high-mass-loading conditions. To mitigate the transport limitations caused via increased loading, strategies such as constructing multidimensionally interconnected networks and optimizing hierarchical pore size distributions are required to ensure ultralow transport resistance for both electrons and ions, even in the deep regions of electrodes. This is essential for achieving simultaneous enhancement of areal capacitance and frequency response.

From an engineering perspective, the scalable fabrication of large-area, highly uniform ordered electrodes remains a key bottleneck in practical applications. Future developments should aim at synthesis strategies with improved generality and process tolerance to enable a smooth transition from centimeter-scale laboratory samples to industrial-scale electrode systems. In addition, some challenges relating to device packaging and circuit integration must be addressed, including minimizing the resistance at electrode/current collector interface, suppressing parasitic effects under high-frequency operation, and optimizing impedance characteristics at target frequencies (e.g., 120 Hz and above). Furthermore, the structural stability of three-dimensional porous architectures under long-term cycling, electro-thermal coupling, and mechanical deformation, as well as the reliability of multi-device integration, will critically determine their feasibility in applications.

Overall, building-unit ordering represents not merely a structural optimization strategy, but a unifying paradigm that bridges materials design, device performance, and application scenarios. With continued advancement of multiscale structural regulation capabilities, in-situ characterization techniques, and theoretical modeling tools, a research on filtering supercapacitor electrodes is expected to evolve from empirically driven exploration toward mechanism-informed and quantitatively guided design, ultimately enabling a broad application in highly integrated and miniaturized electronic systems.