Perovskite-Coated Thermochromic Transparent Wood: A Novel Material for Smart Windows in Energy-Efficient and Sustainable Buildings

Freeze-Cast MIL-53(Al) Porous Materials with High Thermal Insulation and Flame Retardant Properties

The development of materials with superior thermal insulation and flame retardancy is critical for industrial applications and daily life. Metal-organic framework (MOF)@poly(vinyl alcohol) (PVA) (MOF@PVA) aerogel composites have demonstrated remarkable thermal insulation and flame retardancy properties. In this work, MIL-53(Al) was directly mixed with PVA and formed by freeze-drying, and the influence of the pore structure on the thermal insulation and flame retardancy properties of the materials was investigated. The incorporated MIL-53(Al) nanoparticles introduced abundant micro- and mesopores, enhancing the complexity of the pore structure and improving the thermal insulation and flame retardancy properties of the aerogels. The directionally freeze-cast aerogel achieved a thermal conductivity of 0.040 W·mK-1, and maintained excellent thermal insulation ability even at 220 °C. Furthermore, the aerogel exhibited nonflammable and self-extinguishing characteristics. This environmentally friendly manufacturing method provides new ideas for the design of MOF-based composites, thereby expanding their application areas.

Modification of wood lignin and integration with multifunctional polyester nanocomposite

A simple strategy was introduced to develop fluorescent wood with the ability to alter its color when exposed to both visible and ultraviolet lights. Injecting a combination of europium and dysprosium doped aluminate (EDA; 7-12 nm) nanoparticles and polyester resin (PET) into a lignin-modified wood (LMW) produced a translucent smart wooden window with fluorescence and afterglow emission properties. In order to prevent formation of aggregates and improve the preparation process of transparent woods, EDA must be properly disseminated in the polyester matrix. We analyzed the fluorescent wood samples using a variety of spectroscopic and microscopic methods, including energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), photoluminescence spectra, and hardness tests. We found that the photoluminescent woods had an excitation peak at 365 nm and emission peaks at 437 nm and 517 nm. The translucent luminous woods showed rapid and reversible emission response to ultraviolet light. Fluorescence emission was detected for samples with lower EDA content, and afterglow emission was detected for wood samples with higher EDA content. Increases in EDA content were associated with improvements in water resistance and ultraviolet radiation protection in the EDA@PET-infiltrated wood.

Transparent and Efficient Wood-Based Triboelectric Nanogenerators for Energy Harvesting and Self-Powered Sensing

Wood possesses several advantageous qualities including innocuity, low cost, aesthetic appeal, and excellent biocompatibility, and its naturally abundant functional groups and diverse structural forms facilitate functionalization modification. As the most sustainable bio-based material, the combination of wood with triboelectric nanogenerators (TENGs) stands poised to significantly advance the cause of green sustainable production while mitigating the escalating challenges of energy consumption. However, the inherent weak polarizability of natural wood limits its development for TENGs. Herein, we present the pioneering development of a flexible transparent wood-based triboelectric nanogenerator (TW-TENG) combining excellent triboelectrical properties, optical properties, and wood aesthetics through sodium chlorite delignification and epoxy resin impregnation. Thanks to the strong electron-donating groups in the epoxy resin, the TW-TENG obtained an open-circuit voltage of up to ~127 V, marking a remarkable 530% enhancement compared to the original wood. Furthermore, durability and stability were substantiated through 10,000 working cycles. In addition, the introduction of epoxy resin and lignin removal endowed the TW-TENG with excellent optical characteristics, with optical transmittance of up to 88.8%, while preserving the unique texture and aesthetics of the wood completely. Finally, we show the application prospects of TW-TENGs in the fields of self-power supply, motion sensing, and smart home through the demonstration of a TW-TENG in the charging and discharging of capacitors and the output of electrical signals in different scenarios.