Current membrane distillation (MD) is challenged by the inefficiency of water thermal separation from dissolved solutes, controlled by membrane porosity and thermal conductivity. Existing petroleum-derived polymeric membranes face major development barriers. Here, we demonstrate a first robust MD membrane directly fabricated from sustainable wood material. The hydrophobic nanowood membrane had high porosity (89 ± 3%) and hierarchical pore structure with a wide pore size distribution of crystalline cellulose nanofibrils and xylem vessels and lumina (channels) that facilitate water vapor transportation. The thermal conductivity was extremely low in the transverse direction, which reduces conductive heat transport. However, high thermal conductivity along the fiber enables efficient thermal dissipation along the axial direction. As a result, the membrane demonstrated excellent intrinsic vapor permeability (1.44 ± 0.09 kg m−1 K−1 s−1 Pa−1) and thermal efficiency (~70% at 60°C). The properties of thermal efficiency, water flux, scalability, and sustainability make nanowood highly desirable for MD applications.

Summary Two-dimensional (2D) layered materials and their heterostructures have recently been recognized as promising building blocks for futuristic brain-like neuromorphic computing devices. They exhibit unique properties such as near-atomic thickness, dangling-bond-free surfaces, high mechanical robustness, and electrical/optical tunability. Such attributes unattainable with traditional electronic materials are particularly promising for high-performance artificial neurons and synapses, enabling energy-efficient operation, high integration density, and excellent scalability. In this review, diverse 2D materials explored for neuromorphic applications, including graphene, transition metal dichalcogenides, hexagonal boron nitride, and black phosphorous, are comprehensively overviewed. Their promise for neuromorphic applications are fully discussed in terms of material property suitability and device operation principles. Furthermore, up-to-date demonstrations of neuromorphic devices based on 2D materials or their heterostructures are presented. Lastly, the challenges associated with the successful implementation of 2D materials into large-scale devices and their material quality control will be outlined along with the future prospect of these emergent materials.

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In recent years, there has been increasing interest in leveraging two-dimensional (2D) van der Waals (vdW) crystals for infrared (IR) photodetection, exploiting their unusual optoelectrical properties. Some 2D vdW materials with small band gap energies such as graphene and black phosphorus have been explored as stand-alone IR responsive layers in photodetectors. However, the devices incorporating these IR-sensitive 2D layers often exhibited poor performances owing to their preparation issues such as limited scalability and air instability. Herein, we explored wafer-scale 2D platinum ditelluride (PtTe 2 ) layers for near-to-mid IR photodetection by directly growing them onto silicon (Si) wafers. 2D PtTe 2 /Si heterojunctions exhibited wavelengthand intensity-dependent high photocurrents in a spectral range of ∼1−7 μm, significantly outperforming stand-alone 2D PtTe 2 layers. The observed superiority is attributed to their excellent Schottky junction characteristics accompanying suppressed carrier recombination as well as optical absorbance competition between 2D PtTe 2 layers and Si. The direct and scalable growth of 2D PtTe 2 layers was further extended to demonstrate mechanically flexible IR photodetectors.

Hollow silica nanospheres (HSNS) show a promising potential to become good thermal insulators with low thermal conductivity values for construction purposes. The thermal conductivity of HSNSs is dependent on their structural features such as sizes (inner diameter and shell thickness) and shell structures (porous or dense), which are affected by the synthetic methods and procedures including reaction medium, polystyrene template, and silica precursor. . Formation of thermally insulating HSNS was in general favoured by alkaline reaction, whereby highly porous silica shells were formed, promoting less silica per volume of material, thus a lower solid state thermal conductivity. The Knudsen effect is in general reducing the gas thermal conductivity including the gas and pore wall interaction for materials with pore diameters in the nanometer range, which is also valid for our HSNS reported here.Further decreasing the pore sizes would invoke a higher impact from the Knudsen effect. The additional insulating effect of the inter-silica voids (median diameter D50 ≈ 15 nm) within the shell coating contributed also to the insulating properties of HSNS. The synthesis route with tetraethyl orthosilicate 2 (TEOS) was more robust and produced more porous silica shells than the one with water glass (Na2SiO3, WG), although the latter might represent a greener synthetic method.

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their superior mechanical deformability and ultralightness [8] over their conventional rigid counterparts, which allows for multidegree-of-freedom and high load-toweight ratios. [9] Particularly, soft biomorph actuators have drawn substantial interests, benefiting from their structural simplicity coupled with prominent geometrical adaptivity. [10,11] There are configured by interfacing two different materials of distinct thermal expansion properties; e.g., nonconductive polymers of large mechanical deformability and thin conductive heating layers containing conductive pathways. The mismatch of the coefficient of thermal expansion (CTE) of these constituents generates asymmetric thermal expansion, achieving controlled bending displacements. The conventional approach to fabricate the conductive heating layers is to incorporate electrothermal nanomaterials in dispersed forms into polymer matrices. A variety of conductive nanomaterials that have been so far explored include carbon nanotubes (CNTs), graphene, and silver (Ag) nanowires [11][12][13][14][15][16] which congruently achieve high Joule heating efficiency and large mechanical deformability. However, these solution-based approaches suffer from the uncontrolled integration of randomly dispersed materials with limited spatial homogeneity. As a result, the thickness of the integrated nanomaterials becomes inevitably large (i.e., typically >100 nm) and the polymer/ nanomaterial interfaces are unstable upon repeating actuator operations.Recently, 2D transition metal dichalcogenides (TMDs) have shown great promise in various applications owing to their extraordinary thermal, electrical, optical, and physical properties. [17][18][19] Furthermore, their extremely small thickness allows for an unparalleled level of integration adaptability and conformity to objects with uneven surfaces. [20][21][22] A rich library of 2D TMDs spanning from semiconducting-to-metallic properties [23][24][25] were developed, while earlier focus was on utilizing those with sizeable bandgaps for digital electronics. [26][27][28] Meanwhile, gapless metallic 2D TMD layers are gaining increasing attentions for niche applications demanding a combination of high electrical conductivity and large mechanical deformability. [29][30][31] Platinum ditelluride (PtTe 2 ), an emerging class of metallic 2D TMD layers, demonstrated the highest electrical conductivity ever reported in any 2D TMDs developed so far. [24] 2D PtTe 2 layers exhibit superior electrical-to-thermal conversion Biomorph actuators composed of two layers with asymmetric thermal expansion properties are widely explored owing to their high mechanical adaptability. Electrothermal nanomaterials are employed as the Joule heating components in them for controlled thermal expansion, while their large integration thickness often limits resulting actuation performances. This study reports high-performance ultrathin soft biomorph actuators enabled by near atom-thickness 2D platinum ditelluride (PtTe 2 ) layers-a new class of emergent metallic 2D...