Mechanically tough large‐area hierarchical porous graphene films are fabricated by blade‐casting of graphene oxide hydrogel and postcasting reduction. The as‐prepared graphene films, which consist of ...well‐exfoliated graphene nanosheets, possess interpenetrating 3D hierarchical porous structures, high strength and modulus, large specific area, and high electrical conductivity. Flexible film supercapacitors fabricated with the graphene electrodes show superior areal capacitance, good rate performance, and excellent mechanical stability.
Nanoporous laminar membranes composed of multilayered 2D nanomaterials (2D‐NLMs) are increasingly being exploited as a unique material platform for understanding solvated ion transport under ...nanoconfinement and exploring novel nanoionics‐related applications, such as ion sieving, energy storage and harvesting, and in other new ionic devices. Here, the fundamentals of solvation‐involved nanoionics in terms of ionic interactions and their effect on ionic transport behaviors are discussed. This is followed by a summary of key requirements for materials that are being used for solvation‐involved nanoionics research, culminating in a demonstration of unique features of 2D‐NLMs. Selected examples of using 2D‐NLMs to address the key scientific problems related to nanoconfined ion transport and storage are then presented to demonstrate their enormous potential and capabilities for nanoionics research and applications. To conclude, a personal perspective on the challenges and opportunities in this emerging field is presented.
Solvation‐involved nanoionics is the study of ion transport and storage in nanoporous structures immersed in liquids involving various short‐range atomic interactions. The fundamentals are introduced and the progress and opportunities enabled by 2D nanomaterial laminar membranes are discussed, which is of great interest for energy storage, desalination, ionic devices, and others.
Graphene-based nanoporous materials have been extensively explored as high-capacity ion electrosorption electrodes for supercapacitors. However, little attention has been paid to exploiting the ...interactions between electrons that reside in the graphene lattice and the ions adsorbed between the individual graphene sheets. Here we report that the electronic conductance of a multilayered reduced graphene oxide membrane, when used as a supercapacitor electrode, can be modulated by the ionic charging state of the membrane, which gives rise to a collective electrolyte gating effect. This gating effect provides an in-operando approach for probing the charging dynamics of supercapacitors electrically. Using this approach, we observed a pore-size-dependent ionic hysteresis or memory effect in reduced graphene oxide membranes when the interlayer distance is comparable to the ion diameter. Our results may stimulate the design of novel devices based on the ion-electron interactions under nanoconfinement.
The occurrence of an internal short circuit caused by lithium dendrite puncturing the separators is a critical safety issue for lithium batteries. While the investigation of dendrite puncturing ...resistance of commercial polyolefin separators is well-established, nonwoven separators have received fewer relevant studies. Therefore, we assembled lithium-symmetric cells, lithium-sulfur batteries, and lithium-lithium iron phosphate batteries using three commercial nonwoven separators and a homemade micro-fibrillated cellulose nonwoven separator to verify the ability of the nonwoven separator to resist lithium dendrite penetration. The results reveal that even under low current densities, all four types of nonwoven separators are susceptible to dendrite puncturing, leading to both hard short circuits with significant voltage drops, as well as soft short circuits with charging currents or voltage fluctuations. Moreover, the impedance of lithium-symmetric cells is significantly reduced after short circuit, while the charge transfer resistance of lithium-sulfur batteries increases substantially after short circuit. Our findings provide valuable insights for the development of nonwoven separators for use in lithium metal batteries, highlighting the need for further reduction in pore size.
Two-dimensional materials with ultrahigh in-plane thermal conductivity are ideal for heat spreader applications but cause significant thermal contact resistance in complex interfaces, limiting their ...use as thermal interface materials. In this study, we present an interfacial phonon bridge strategy to reduce the thermal contact resistance of boron nitride nanosheets-based composites. By using a low-molecular-weight polymer, we are able to manipulate the alignment of boron nitride nanosheets through sequential stacking and cutting, ultimately achieving flexible thin films with a layer of arc-like structure superimposed on perpendicularly aligned ones. Our results suggest that arc-like structure can act as a phonon bridge to lower the contact resistance by 70% through reducing phonon back-reflection and enhancing phonon coupling efficiency at the boundary. The resulting composites exhibit ultralow thermal contact resistance of 0.059 in
KW
, demonstrating effective cooling of fast-charging batteries at a thickness 2-5 times thinner than commercial products.
Purpose
Accurate evaluation of hypoxia is particularly important in patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy. The aim of this study was to propose a novel imaging strategy ...for quantitative three-dimensional (3D) evaluation of hypoxia in a small animal model of NPC.
Methods
A carbonic anhydrase IX (CAIX)-specific molecular probe (CAIX-800) was developed for imaging of hypoxia. Mouse models of subcutaneous, orthotopic, and spontaneous lymph node metastasis from NPC (5 mice per group) were established to assess the imaging strategy. A multi-modality imaging method that consisted of a hybrid combination of fluorescence molecular tomography-computed tomography (FMT-CT) and multispectral optoacoustic tomography (MSOT) was used for 3D quantitative evaluation of tumour hypoxia. Magnetic resonance imaging, histological examination, and immunohistochemical analysis were used as references for comparison and validation.
Results
In the early stage of NPC (2 weeks after implantation), FMT-CT enabled precise 3D localisation of the hypoxia biomarker with high sensitivity. At the advanced stage (6 weeks after implantation), MSOT allowed multispectral analysis of the biomarker and haemoglobin molecules with high resolution. The combination of high sensitivity and high resolution from FMT-CT and MSOT could not only detect hypoxia in small-sized NPCs but also visualise the heterogeneity of hypoxia in 3D.
Conclusions
Integration of FMT-CT and MSOT could allow comprehensive and quantifiable evaluation of hypoxia in NPC. These findings may potentially benefit patients with NPC undergoing radiotherapy in the future.
Graphical abstract
A novel multimodality imaging strategy for three-dimensional evaluation of tumour hypoxia in an orthotopic model of nasopharyngeal carcinoma.
Recently, increasing attention has been paid to magneto-conjugated polymer core-shell nanoparticles （NPs） as theranostic platforms. However, the utilization of surfactants and extra oxidizing agents ...with potential toxicity in synthesis, the lack of general methods for the controlled synthesis of various kinds of magnetic NP （MNP）@conjugated polymer NPs, and the difficulty of obtaining balanced magneto-optical properties have greatly limited the applications of magneto-conjugated polymers in theranostics. We developed an in situ surface polymerization method free of extra surfactants and oxidizing agents to synthesize MNP@polypyrrole （PPy） NPs with balanced, prominent magneto-optical properties. MNP@PPy NPs with an adjustable size, different shapes, and a controlled shell thickness were obtained using this method. The method was extended to synthesize other MNP-conjugated polymer core-shell NPs, such as MNP@polyaniline and MNP@poly（3,4-ethylenedioxythiophene）：poly（4- styrenesulfonate） （PEDOT：PSS）. We discuss the formation mechanism of the proposed method according to our experimental results. Finally, using the optical and magnetic properties of the obtained MNP@PEDOT：PSS NPs, in vivo multimodal imaging-guided hyperthermia was induced in mice, achieving an excellent tumor-ablation therapeutic effect. Our work is beneficial for extending the application of MNP-conjugated polymer core-shell NPs in the biomedical field.
Electrochemical oxidation of graphite has emerged as a sustainable and straightforward approach for the scalable synthesis of graphene oxide (GO). However, the reduction of electrochemically-derived ...GO (EGO) has received limited attention. Here, we present a rapid microwave reduction process specifically tailored for EGO, which exhibits distinct properties compared with chemically-derived GO (CGO). Unlike CGO membranes that require several minutes of microwave irradiation for reduction, EGO membranes can be transformed into high-crystalline graphene membranes (HCGM) in just 3 s, without pre-treatment or additional triggers. The resulting HCGM displays a significant aromatic domain size (∼100 nm), a high C/O atomic ratio (∼33), and impressive electrical conductivity (∼5 × 10
4
S m
−1
), surpassing previously reported microwave-reduced graphene. The remarkable efficiency of microwave reduction can be attributed to the unique molecular structure of EGO with abundant aromatic domains which enable efficient microwave absorption, inducing transient volumetric heating of EGO membranes. This study provides mechanistic insights into the microwave reduction process of GO and offers a facile and scalable pathway for HCGM production.
Traumatic bone marrow lesions (TBMLs) are considered to represent a range of concealed bone injuries, including haemorrhage, infarction, and localised oedema caused by trabecular microfracture ...occurring in the cancellous bone. If TBMLs are not managed timeously, they potentially cause a series of complications that can lead to irreversible morbidity and prolonged recovery time. This article reviews interesting image findings of bone marrow lesions in dual-energy computed tomography (DECT). In addition to combining the benefits of traditional CT imaging, DECT also reveals and identifies various structures using diverse attenuation characteristics of different radiographic spectra. Therefore, DECT has the capacity to detect TBMLs, which have traditionally been diagnosed using MRI. Through evaluating DECT virtual non-calcium maps, the detection of TBMLs is rendered easier and more efficient in some acute accidents.
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