Approaching Superfoldable Thickness-Limit Carbon Nanofiber Membranes Transformed from Water-Soluble PVA.

Recent progress in flexible electronics has attracted tremendous attention. However, it is still difficult to prepare superfoldable conductive materials with good biocompatibility, high sensing sensitivities, and large specific surface areas. It is expected that biomimetic methods and water-soluble precursors like poly(vinyl alcohol) (PVA) for electrospinning will be utilized to solve the above problems. Inspired by the multistage water management process of a spider spinning dragline silk, we have established a combined biomimetic technique, hydrocolloid electrospinning coupled with temperature gradient dehydration, with a carbonization technique. PVA-driven superfoldable carbon nanofiber membranes (PVA-SFCNFMs) have been prepared that not only possess a >60% micropore ratio and a 1368.8 m2/g specific surface area but also can withstand 180° real folding for 100 000 cycles, approaching the thickness limit without structure fracture. Furthermore, these membranes provide highly sensitive sensing and superior biocompatible interfaces. The molecular mechanism to improve carbon conversion and the folding mechanism to obtain "three-level dispersing stress" for the PVA-SFCNFMs have been proposed.

Alternating Current Electroluminescence for Human-Interactive Sensing Displays.

The development of stimuli-interactive displays based on alternating current (AC)-driven electroluminescence (EL) is of great interest, owing to their simple device architectures suitable for wearable applications requiring resilient mechanical flexibility and stretchability. AC-EL displays can serve as emerging platforms for various human-interactive sensing displays (HISDs) where human information is electrically detected and directly visualized using EL, promoting the development of the interaction of human-machine technologies. This review provides a holistic overview of the latest developments in AC-EL displays with an emphasis on their applications for HISDs. AC-EL displays based on exciton recombination or impact excitations of hot electrons are classified into four representative groups depending upon their device architecture: 1) displays without insulating layers, 2) displays with single insulating layers, 3) displays with double insulating layers, and 4) displays with EL materials embedded in an insulating matrix. State-of-the-art AC HISDs are discussed. Furthermore, emerging stimuli-interactive AC-EL displays are described, followed by a discussion of scientific and engineering challenges and perspectives for future stimuli-interactive AC-EL displays serving as photo-electronic human-machine interfaces.

Mesoporous Cubic Nanocages Assembled by Coupled Monolayers With 100% Theoretical Capacity and Robust Cycling.

High capacity and long cycling often conflict with each other in electrode materials. Despite extensive efforts in structural design, it remains challenging to simultaneously achieve dual high electrochemical properties. In this study, we prepared brand-new completely uniform mesoporous cubic-cages assembled by large d-spacing Ni(OH)2 coupled monolayers intercalated with VO4 3- (NiCMCs) using a biomimetic approach. Such unique mesoporous structural configuration results in an almost full atomic exposure with an amazing specific surface area of 505 m2/g and atomic utilization efficiency close to the theoretical limit, which is the highest value and far surpasses all of the reported Ni(OH)2. Thus, a breakthrough in simultaneously attaining high capacity approaching the 100% theoretical value and robust cycling of 10,000 cycles is achieved, setting a new precedent in achieving double-high attributes. When combined with high-performance Bi2O3 hexagonal nanotubes, the resulting aqueous battery exhibits an ultrahigh energy density of 115 Wh/kg and an outstanding power density of 9.5 kW/kg among the same kind. Characterizations and simulations reveal the important role of large interlayer spacing intercalation units and mesoporous cages for excellent electrochemical thermodynamics and kinetics. This work represents a milestone in developing "double-high" electrode materials, pointing in the direction for related research and paving the way for their practical application.

Fabrication of three-dimension hierarchical structure CuO nanoflowers and their antifungal mechanism against Bipolaris sorokiniana.

Nanomaterials are widely investigated in sustainable agriculture owing to their unique physicochemical properties, especially Cu-based nanomaterial with eco-friendliness and essential for plant. However, the effect of CuO nanomaterial on Bipolaris sorokiniana (B. sorokiniana) is yet to be systematically understood. In this study, a three-dimension hierarchical structure CuO nanoflower (CuO NF) with ultrathin petals and excellent dispersibility in water was constructed and proved to have outstanding antifungal activity against B. sorokiniana with the inhibition rate of 86 % in mycelial growth, 74 % in mycelial dry weight and 75 % in conidial germination. Furthermore, the antifungal mechanism was assigned to the production of reactive oxygen species in intracellular caused by antioxidant mimicking activity of CuO NF to damage of cell membrane integrity and result cellular leakage. Additionally, the good control effect of CuO NF on wheat diseases caused by B. sorokiniana was demonstrated through pot experiment. This article firstly reveals the antifungal activity and mechanism of CuO NF on B. sorokiniana, and establishes the relationship between enzyme-like activity of CuO NF and its antifungal activity, which provides a promising application of Cu-based nanomaterial as nanofungicide in plant protection and a theoretical foundation for structure design of nanomaterials to improve their antifungal activities.

Meter-scale van der Waals films manufactured via one-step roll printing.

A weak van der Waals (vdW) force in layered materials enables their isolation into thin flakes through mechanical exfoliation while sustaining their intrinsic electronic and optical properties. Here, we introduce a universal roll-printing method capable of producing vdW multilayer films on wafer-to-meter scale. This process uses sequential exfoliation and transfer of layered materials from the powder sources to target substrates through a repeated rolling of a cylindrical metal drum. We achieve uniformly coated films with a library of vdW powders on various mechanically rigid and flexible substrates. The printed films are configured into different devices including light-emitting diodes and photodetectors. The presented technique offers substantial benefits in terms of cost efficiency and a low thermal budget while offering high material quality.

Dual Carbon Design Strategy for Anodes of Sodium-Ion Battery: Mesoporous CoS2/CoO on Open Framework Carbon-Spheres with rGO Encapsulating.

Transition metal sulfides and oxides with high theoretical capacities have been regarded as promising anode candidates for a sodium-ion battery (SIB); however, they have critical issues including sluggish electrochemical kinetics and poor long-term stability. Herein, a dual carbon design strategy is proposed to integrate with highly active heterojunctions to overcome the above issues. In this new design, CoS2/CoO hollow dodecahedron heterojunctions are sandwiched between open framework carbon-spheres (OFCs) and a reduced graphene oxide (rGO) nanomembrane (OFC@CoS2/CoO@rGO). The CoS2/CoO heterojunctions effectively promote electron transfer on their surface and provide more electrochemical active sites through their hierarchical hollow structures assembled by nanodots. Meanwhile, the dual-carbon framework forms a highly conductive network that enables a better rate capability. More importantly, the dual carbon can greatly buffer volume expansion and stable reaction interfaces of electrode material during the charge/discharge process. Benefitting from their synergistical effects, the OFC@CoS2/CoO@rGO electrode achieves a high reversible capacity of 460 mAh g-1 at 0.05 A g-1 and still maintains 205.3 mAh g-1 even when current density is increased by 200 times when used as an anode material for SIBs. Their cycling property is also remarkable with a maintained capacity of 161 mAh g-1 after 3500 charging/discharging cycles at a high current density of 1 A g-1. The dual-carbon strategy is demonstrated to be effective for enhanced reaction kinetics and long-term cycling property, providing siginificant guidance for preparing other high-performance electrode materials.

Bioinspired Nanocomposites with Self-Adaptive Stress Dispersion for Super-Foldable Electrodes.

In flexible electronics, appropriate inlaid structures for stress dispersion to avoid excessive deformation that can break chemical bonds are lacking, which greatly hinders the fabrication of super-foldable composite materials capable of sustaining numerous times of true-folding. Here, mimicking the microstructures of both cuit cocoon possessing super-flexible property and Mimosa leaf featuring reversible scatheless folding, super-foldable C-web/FeOOH-nanocone (SFCFe) conductive nanocomposites are prepared, which display cone-arrays on fiber structures similar to Mimosa leaf, as well as non-crosslinked junctions, slidable nanofibers, separable layers, and compressible network like cuit cocoon. Remarkably, the SFCFe can undergo over 100 000 times of repeated true-folding without structural damage or electrical conductivity degradation. The mechanism underlying this super-foldable performance is further investigated by real-time scanning electron microscopy folding characterization and finite-element simulations. The results indicate its self-adaptive stress-dispersion mechanism originating from multilevel biomimetic structures. Notably, the SFCFe demonstrates its prospect as a super-foldable anode electrode for aqueous batteries, which shows not only high capacities and satisfactory cycling stability, but also completely coincident cyclic voltammetry and galvanostatic charge-discharge curves throughout the 100 000 times of true-folding. This work reports a mechanical design considering the self-adaptive stress dispersion mechanism, which can realize a scatheless super-foldable electrode for soft-matter electronics.

A pie-like structure double-sidedly assembled with ZnO-nanodisks vertically on Cu-nanoplates and its photochemical properties.

A novel pie-like structure of vertically stacked ZnO-nanodisks on Cu-nanoplates interlayer is prepared for the first time by a facile synthesis. The photochemical activity of the as-prepared samples was evaluated by the degradation of Rhodamine B (RhB) under UV-light. Because of the formation of heterojunction and closely-bonded layered structure, the novel nanocomposites can restrain the recombination of charge carriers and have better collection ability of light. The photocatalytic experiments show that the composites are 258% of the catalytic activity of pure ZnO-nanodisks prepared by the same method, and the target pollutant RhB was almost completely degraded (96.5%) within only 10 mins. The novel Cu-nanoplates/ZnO-nanodisks assembled materials with greatly promoted performance are of significant interest for chemical and environmental applications.

Biomimetic and Bioinspired Synthesis of Nanomaterials/Nanostructures.

In recent years, due to its unparalleled advantages, the biomimetic and bioinspired synthesis of nanomaterials/nanostructures has drawn increasing interest and attention. Generally, biomimetic synthesis can be conducted either by mimicking the functions of natural materials/structures or by mimicking the biological processes that organisms employ to produce substances or materials. Biomimetic synthesis is therefore divided here into "functional biomimetic synthesis" and "process biomimetic synthesis". Process biomimetic synthesis is the focus of this review. First, the above two terms are defined and their relationship is discussed. Next different levels of biological processes that can be used for process biomimetic synthesis are compiled. Then the current progress of process biomimetic synthesis is systematically summarized and reviewed from the following five perspectives: i) elementary biomimetic system via biomass templates, ii) high-level biomimetic system via soft/hard-combined films, iii) intelligent biomimetic systems via liquid membranes, iv) living-organism biomimetic systems, and v) macromolecular bioinspired systems. Moreover, for these five biomimetic systems, the synthesis procedures, basic principles, and relationships are discussed, and the challenges that are encountered and directions for further development are considered.

A high-performance dual-function material: self-assembled super long α-Fe2O3 hollow tubes with multiple heteroatom (C-, N- and S-) doping.

Novel heteroatom self-doped super long α-Fe2O3 hollow tubes have been synthesized by the combination of hydrothermal and calcination techniques using the chicken eggshell membrane as a template and a dopant. The obtained α-Fe2O3 super long hollow tubes are composed of closely arranged building blocks (α-Fe2O3 nanorods), which are connected to each other and provide a lot of grain boundaries. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and nitrogen adsorption-desorption analysis were used to characterize the structure of the synthesized products. To demonstrate their potential applications, the as-synthesized samples were applied to ethanol (C2H5OH) gas sensors and supercapacitors. When applied as a gas sensor, the α-Fe2O3 material exhibits a high gas sensitivity, excellent recovery properties (9 s at 100 ppm C2H5OH concentration) and perfect selectivity to ethanol. As an electrode in a supercapacitor, α-Fe2O3 shows a high specific capacitance (330 F g(-1) at a current density of 0.5 A g(-1)) with good cycling stability (64% maintained over after 2000 cycles). The excellent sensing and supercapacitor performances could be attributed to the unique super long hollow tubes combined with the abundant pore volume and the small amount of heteroatom doping.