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Covalent organic framework (COF) aerogels arehierarchically porous polymeric materials with ultrahigh specific surface area, making them attractive for wide applications such as molecular capture, adsorption, and catalysis. Previous COF aerogel studies have focused on varying their chemical structures and linkage chemistries to fine-tune material properties and functionality, most of which have reported relatively unsatisfying performance (e.g., poor mechanical strength and strain tolerance). This study describes the synthesis and characterization of COF nanocomposite aerogels, whose material properties and functionality are effectively engineered through the incorporation of reinforcing fillers/binders or functional additives. Boron nitride (BN) fillers, cross-linked poly(acrylic acid) (XPAA) binders, and gold nanoparticles (AuNps) are incorporated into 1,3,5-tris(aminophenyl)benzene-terephthaldehyde (TAPB-PDA) COF aerogel matrices to form homogeneous nanocomposite aerogels with enhanced mechanical properties and unique photothermal conversion capabilities. Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy results confirm the successful filler/additive inclusion into the final COF nanocomposite aerogels. Specifically, BN filler loading at ∼17 wt % relative to final COF mass doubles COF aerogel’s Young’s modulus from 11 to 22 kPa according to mechanical compression tests, with only ∼10% reduction in COF’s accessible mesopores’ surface area according to nitrogen porosimeter analyses. Meanwhile, incorporating ∼7 wt % XPAA relative to final COF mass improves the Young’s modulus to 21 kPa, while increasing the aerogel’s yield strain from 10 to 65% strain, although this leads to a ∼35% reduction in COF’s accessible mesopores’ surface area. Furthermore, photothermal AuNps are incorporated to form functional COF nanocomposite aerogels, whose overall temperature increases by 5.5 °C after 1 sun (AM1.5G, 1000 W m−2) irradiation. Overall, this study demonstrates potential routes to fabricate hierarchically porous COF nanocomposite aerogels with high specific surface area, robust mechanical stability, and unique photothermal functionality, which hold promises for applications in adsorption separation, gas storage, and photocatalysis. 

Abstract Polycrystalline yttrium aluminum garnet (YAG) ceramic doped with neodymium (Nd), referred to as Nd:YAG, is widely used in solid‐state lasers. However, conventional powder metallurgy methods suffer from expenses, time consumption, and limitations in customizing structures. This study introduces a novel approach for creating Nd:YAG ceramics with 3D free‐form structures from micron (∼70 µm) to centimeter scales. Firstly, sol‐gel synthesis is employed to form photocurable colloidal solutions. Subsequently, by utilizing a home‐built micro‐continuous liquid interface printing process, precursors are printed into 3D poly(acrylic acid) hydrogels containing yttrium, aluminum, and neodymium hydroxides, with a resolution of 5.8 µmpixel⁻¹at a speed of 10 µm s⁻¹. After the hydrogels undergo thermal dehydration, debinding, and sintering, polycrystalline Nd:YAG ceramics featuring distinguishable grains are successfully produced. By optimizing the concentrations of the sintering aids (tetraethyl orthosilicate) and neodymium trichloride (NdCl₃), the resultant samples exhibit satisfactory photoluminescence, emitting light concentrated at 1064 nm when stimulated by a 532 nm laser. Additionally, Nd:YAG ceramics with various 3D geometries (e.g., cone, spiral, and angled pillar) are printed and characterized, which demonstrates the potential for applications, such as laser and amplifier fibers, couplers, and splitters in optical circuits, as well as gain metamaterials or metasurfaces. 

The control of resonant metasurface for electromagnetically induced transparency (EIT) offers unprecedented opportunities to tailor lightwave coupling at the nanoscale leading to many important applications including slow light devices, optical filters, chemical and biosensors. However, the realization of EIT relies on the high degree of structural asymmetry by positional displacement of optically resonant structures, which usually lead to low quality factor (Q-factor) responses due to the light leakage from structural discontinuity from asymmetric displacements. In this work, we demonstrate a new pathway to create high quality EIT metasurface without any displacement of constituent resonator elements. The mechanism is based on the detuning of the resonator modes which generate dark-bright mode interference by simply introducing a slot in metasurface unit cells (meta-atoms). More importantly, the slot diameter and position on the meta-atom can be modulated to tune the transmittance and quality factor (Q-factor) of the metasurface, leading to a Q-factor of 1190 and near unity transmission at the same time. Our work provides a new degree of freedom in designing optically resonant elements for metamaterials and metasurfaces with tailored wave propagation and properties. 

Abstract The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.