Biological tissues generally exhibit excellent anisotropic mechanical properties owing to their well-developed microstructures. Inspired by the aligned structure in muscles, a highly anisotropic, strong, and conductive wood hydrogel is developed by fully utilizing the high-tensile strength of natural wood, and the flexibility and high-water content of hydrogels. The wood hydrogel exhibits a high-tensile strength of 36 MPa along the longitudinal direction due to the strong bonding and cross-linking between the aligned cellulose nanofibers (CNFs) in wood and the polyacrylamide (PAM) polymer. The wood hydrogel is 5 times and 500 times stronger than the bacterial cellulose hydrogels (7.2 MPa) and the unmodified PAM hydrogel (0.072 MPa), respectively, representing one of the strongest hydrogels ever reported. Due to the negatively charged aligned CNF, the wood hydrogel is also an excellent nanofluidic conduit with an ionic conductivity of up to 5 × 10 S cm at low concentrations for highly selective ion transport, akin to biological muscle tissue. The work offers a promising strategy to fabricate a wide variety of strong, anisotropic, flexible, and ionically conductive wood-based hydrogels for potential biomaterials and nanofluidic applications.

Plastic waste has been increasingly transferred from land into the ocean and has accumulated within the food chain, causing a great threat to the environment and human health, indicating that fabricating an eco‐friendly and biodegradable replacement is urgent. Paper made of cellulose is attractive in terms of its favorable biodegradability, resource abundance, large manufacturing scale, and low material cost, but is usually hindered by its inferior stability against water and poor mechanical strength for plastic replacement. Here, inspired by the reinforcement principle of cellulose and lignin in natural wood, a strong and hydrostable cellulosic material is developed by integrating lignin into the cellulose. Lignin as a reinforced matrix is incorporated to the cellulose fiber scaffold by successive infiltration and mechanical hot‐pressing treatments. The resulting lignin‐cellulose composite exhibits an outstanding isotropic tensile strength of 200 MPa, which is significantly higher than that of conventional cellulose paper (40 MPa) and some commercial petroleum‐based plastics. Additionally, the composite demonstrates a superior wet strength of 50 MPa. Adding lignin also improves the thermostability and UV‐blocking performance of cellulose paper. The demonstrated lignin‐cellulose composite is biodegradable and eco‐friendly with both components from natural wood, which represents a promising alternative that can potentially replace the nonbiodegradable plastics.

cycling life, and the second results in a large charge-discharge overpotential, and the last impedes the transport of ions (electrolyte) and/or O 2 gas, both of which are essential for an effective electrochemical reaction. In addition, conventional Li-O 2 batteries generally demonstrate limited areal capacity (usually less than 10 mAh cm −2 ) with low active material loading, which limits their potential for practical applications that require high areal capacity and energy density.Tremendous efforts have been dedicated to overcome the electrolyte decomposition and Li 2 O 2 issues. For example, Zhang and Zhou [10] developed an ionic liquid (IL)-based gel electrolyte for Li-O 2 batteries to replace the liquid organic electrolyte widely used in conventional lithium ion batteries. The ILs demonstrate excellent nonvolatility, hydrophobicity, high thermal stability, and broad electrochemical windows, thus ensuring both electrochemical and environmental stability under repeated charging/discharging in ambient conditions. Under similar conditions, several solid-state or hybrid electrolytes have also been developed to prevent the attack of O 2 radicals. [11][12][13] Meanwhile, Huang and co-workers [4] recently proposed a novel strategy to resolve the insulating nature of the Li-O 2 discharge products using solution-based catalysts and redox mediators. However, very limited progress has been made in electrode structure engineering to construct decoupled or triple pathways for the multiphase and more effective transport of electrons, Li + ions, and O 2 gas, [10,14] especially for thick electrode design where these multiphase transports become more difficult.Multiphase transport occurs continuously in trees, with water transporting ions from the roots to the upper trunk and photosynthetic products from the leaves being distributed throughout the organism (Figure 1A). The interconnected passages comprising lumina and vessels (i.e., wood channels) are vital for multiphase transport in trees. Inspired by such an efficient and noncompetitive transport system, we developed a flexible wood (F-Wood)-based current-collector-free cathode directly from natural balsa wood ( Figure 1B). Mechanical flexibility was imparted using a facile chemical treatment to remove lignin and hemicellulose, and subsequent carbon nanotube (CNT) coating was used to generate high electrical conductivity.Trees have an abundant network of channels for the multiphase transport of water, ions, and nutrients. Recent studies have revealed that multiphase transport of ions, oxygen (O 2 ) gas, and electrons also plays a fundamental role in lithium-oxygen (Li-O 2 ) batteries. The similarity in transport behavior of both systems is the inspiration for the development of Li-O 2 batteries from natural wood featuring noncompetitive and continuous individual pathways for ions, O 2 , and electrons. Using a delignification treatment and a subsequent carbon nanotube/Ru nanoparticle coating process, one is able to convert a rigid and electrically insulating wood membrane ...

materials (e.g., boron nitride (BN), graphene, and MoS 2 ) have great potential in emerging energy, environmental, and electronics applications. Assembly of 2D materials into vertically aligned structures is highly desirable (e.g., low tortuosity for rapid ion transport in fast charging−discharging batteries, guiding thermal transport for efficient thermal management), yet extremely challenging due to the energetically unfavorable in processing. Herein, we reported a general three-dimensional (3D) printing method to fabricate vertically aligned 2D materials in multiscale, using BN nanosheet as the proof-of-concept. The 3D-printed macroscale rods are composed of vertically aligned BN nanosheets at the nanoscale. The formation of the hierarchical aligned structure is enabled by the optimized ink that holds a significant shear-thinning behavior and an ultrahigh storage modulus, as identified at a narrow region in the printability diagram. The resulting vertically aligned multiscale structure with 2D nanosheets demonstrated an outstanding throughplane thermal conductivity, up to 5.65 W m −1 K −1 , significantly higher than the value of conventional BN based structures where the sheets are horizontally aligned. The vertical 3D printing of 2D BN nanosheets can be expanded to other 2D materials in constructing hierarchically aligned structures for a range of emerging technologies such as batteries, membranes, and structural materials.

Among all the plastic pollution, straws have brought particularly intricate problems since they are single use, consumed in a large volume, cannot be recycled in most places, and can never be fully degraded. To solve this problem, replacements for plastic straws are being developed following with the global trend of plastic straw bans. Nevertheless, none of the available degradable alternatives are satisfactory due to drawbacks including poor natural degradability, high cost, low mechanical performance, and poor water stability. Here, all-natural degradable straws are designed by hybridizing cellulose nanofibers and microfibers in a binder-free manner. Straws are fabricated by rolling up the wet hybrid film and sealed by the internal hydrogen bonding formed among the cellulose fibers after drying. The cellulose hybrid straws show exceptional behaviors including 1) excellent mechanical performance (high tensile strength of ≈70 MPa and high ductility with a fracture strain of 12.7%), 2) sufficient hydrostability (10× wet mechanical strength compared to commercial paper straw), 3) low cost, and 4) high natural degradability. Given the low-cost raw materials, the binder-free hybrid design based on cellulose structure can potentially be a suitable solution to solve the environmental challenges brought by the enormous usage of plastics straws.