Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates.

Emerging solar desalination by interfacial evaporation shows great potential in response to global water scarcity because of its high solar‐to‐vapor efficiency, low environmental impact, and off‐grid capability. However, solute accumulation at the heating interface has severely impacted the performance and long‐term stability of current solar evaporation systems. Here, a self‐regenerating solar evaporator featuring excellent antifouling properties using a rationally designed artificial channel‐array in a natural wood substrate is reported. Upon solar evaporation, salt concentration gradients are formed between the millimeter‐sized drilled channels (with a low salt concentration) and the microsized natural wood channels (with a high salt concentration) due to their different hydraulic conductivities. The concentration gradients allow spontaneous interchannel salt exchange through the 1–2 µm pits, leading to the dilution of salt in the microsized wood channels. The drilled channels with high hydraulic conductivities thus function as salt‐rejection pathways, which can rapidly exchange the salt with the bulk solution, enabling the real‐time self‐regeneration of the evaporator. Compared to other salt‐rejection designs, the solar evaporator exhibits the highest efficiency (≈75%) in a highly concentrated salt solution (20 wt% NaCl) under 1 sun irradiation, as well as long‐term stability (over 100 h of continuous operation).

A bimodal porous evaporator is developed for efficient, stable, and salt-rejecting desalination of seawater and high-concentration brines.

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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.

the current collector. Recently, progresses have been made in thick electrode architecture design by incorporating external magnetic fields and carbon templates for fast charge transfer kinetics, but the complicated producing processes and fragile electrode mechanical properties limit their ability for practical applications. [10][11][12][13][14][15] Fiber like carbon materials with large aspect ratio, such as carbon nanotubes (CNT), can significantly improve electrode mechanical strength and energy density due to its excellent electron conductivity and good compatibility to form continuous network with lower electrical percolation threshold. [16][17][18][19] Nonetheless, CNT is still constrained to complicated syntheses by expensive or low throughput methods which limits their application in bunch commercial products.Cellulose nanofiber (CNF) as an emerging biomass binder shows great potential in field of flexible and freestanding electrode fabrication due to its 1D nanostructure, excellent electrochemical stability, and robust mechanical property. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] However, conventional CNFbased electrodes are characterized by low energy density owing to inadequate conductivity arising from the poor compatibility between CNF and conductive agents. Here, we report a conductive nanofiber network with decoupled electron and ion transfer pathways based on neutral carbon black (CB) nanoparticles and negatively charged CNF for high-loading thick electrode (up to 60 mg cm −2 ). This unique conductive CNF is achieved by a spontaneous electrostatic self-assembly technology as shown in Figure 1a. Microsize cellulose pulp was pretreated by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidization, which selectively oxidized the C6-hydroxyl group to a carboxyl group, leading to a strong negatively charged surface of the cellulose fibers. Negatively charged CNF was then obtained by disintegrating the microsized cellulose fiber down to the nanoscale by a probe sonication process for 1 h (Figures S1-S5, Supporting Information). Such negatively charged CNF can firmly absorb neutral CB nanoparticles by electrostatic attraction, forming a conformal conductive nanofiber. The conductive CNF can further assemble into an interconnected 3D network and tightly wrap the active electrode materials such as lithium iron phosphate (LFP) during the freeze-drying process (Figure 1b).Thick electrodes are appealing for high energy density devices but succumb to sluggish charge transfer kinetics and poor mechanical stability. Nanomaterials with large aspect ratio, such as carbon nanotubes, can help improve the charge transfer and strength of thick electrodes but represent a costly solution which hinders their utility outside of "lab scale production." Here, a conductive nanofiber network with decoupled electron and ion transfer pathways by the conformal electrostatic assembly of neutral carbon black particles on negatively charged cellulose nanofibers is reported. After integrating with ...

Lightweight structural materials with high strength are desirable for advanced applications in transportation, construction, automotive, and aerospace. Bamboo is one of the fastest growing plants with a peak growth rate up to 100 cm per day. Here, a simple and effective top‐down approach is designed for processing natural bamboo into a lightweight yet strong bulk structural material with a record high tensile strength of ≈1 GPa and toughness of 9.74 MJ m−3. More specifically, bamboo is densified by the partial removal of its lignin and hemicellulose, followed by hot‐pressing. Long, aligned cellulose nanofibrils with dramatically increased hydrogen bonds and largely reduced structural defects in the densified bamboo structure contribute to its high mechanical tensile strength, flexural strength, and toughness. The low density of lignocellulose in the densified bamboo leads to a specific strength of 777 MPa cm3 g−1, which is significantly greater than other reported bamboo materials and most structural materials (e.g., natural polymers, plastics, steels, and alloys). This work demonstrates a potential large‐scale production of lightweight, strong bulk structural materials from abundant, fast‐growing, and sustainable bamboo.

Nowadays, energy-saving building materials are important for reducing indoor energy consumption by enabling better thermal insulation, promoting effective sunlight harvesting and offering comfortable indoor lighting. Here, we demonstrate a novel scalable aesthetic transparent wood (called aesthetic wood hereafter) with combined aesthetic features (e.g. intact wood patterns), excellent optical properties (an average transmittance of~80% and a haze of~93%), good UV-blocking ability, and low thermal conductivity (0.24 W m −1 K −1) based on a process of spatially selective delignification and epoxy infiltration. Moreover, the rapid fabrication process and mechanical robustness (a high longitudinal tensile strength of 91.95 MPa and toughness of 2.73 MJ m −3) of the aesthetic wood facilitate good scale-up capability (320 mm × 170 mm × 0.6 mm) while saving large amounts of time and energy. The aesthetic wood holds great potential in energy-efficient building applications, such as glass ceilings, rooftops, transparent decorations, and indoor panels.