Silk fibroin with sophisticated hierarchical architectures from nano to macro scale shows excellent mechanical properties, good biocompatibility, and outstanding processability. In particular, the crystalline region in silk fibroin contributes high strength and toughness. However, it is difficult to obtain the crystalline silk nanofibrils or nanosheets through top-down methods. The existing silk-derived components are mainly amorphous and sacrifice the delicate structure of the pristine silk. Herein, we report a gentle method to extract the crystalline silk nanosheet (SNS) from the degummed silk fibers. The crystalline SNS has seven strands of β-sheet nanocrystal layer and shows a thickness of 2.75 nm. It can assemble into a membrane via a vacuum filtration process and shows high transparency, excellent thermal stability, outstanding cytocompatibility, and efficient dye interception. Moreover, without external stimuli, the crystalline SNS is capable of reversibly self-assembling to well-organized microfibers. The crystalline SNS is not only a new member of silk fibroin derivatives, but also a promising assemblable unit for versatile applications. We anticipate this work will provide a new insight into the construction and applications of diverse two-dimensional (2D) functional silk materials.

Synthesizing large-area ultrathin two-dimensional (2D) nanostructures in aqueous media has received considerable increasing attention but remains a big challenge. Herein, we report a facile method for the synthesis of two unprecedented large-area ultrathin 2D supramolecular nanosheets via ionic self-assembly in water. Upon consideration of electrostatic interaction and repulsive effect, deprotonated tetrakis(4-carboxyphenyl)porphyrin (TCPP) or Fe(III) tetra(4-carboxyphenyl)porphine chloride (TCPP(Fe)) as connection vertex and protonated bis(2-dimethylaminoethyl) ether (BDMAEE) unit as bridging edge connect with each other to form few-layer 2D nanosheet with a thickness of ~ 1.8-1.9 nm, while the lateral size can close to one hundred micrometers. Moreover, the well-dispersed 2D TCPP(Fe)-BDMAEE with heme-like active center displays intrinsic peroxidase-like catalytic activity, which can be used to detect hydrogen peroxide. The present facile strategy highlights new opportunities in constructing large-area ultrathin 2D supramolecular nanomaterials and paves the avenue to expand their potential applications.

Silicon with high specific capacity is deemed an ideal anode material for lithium ion batteries, which, however suffers from low cycling life due to its dramatic volume changes. Water-soluble polymer binders recently gain increasing attention by providing an eco-friendly and low-cost way in improving the cycling stability of Si-based anodes. Herein, a novel bioinspired supramolecular mineral hydrogel binder consisting of polyacrylic acid (PAA) physically crosslinked with amorphous calcium carbonate (ACC) nanoparticles is designed for high-performance anodes made from low-cost microsized Si particles. Owing to its organic-inorganic hydrophilic nature, ACC-PAA hybrid binder exhibits the reported highest modulus (~ 22 GPa) for polymer binders in electrolyte, even higher than lithiated Si species (Li1₅Si₄, ~ 12 GPa). Together with its excellent adhesion and electrochemical stability, ACC-PAA binder can effectively suppress the pulverization of Si particles and maintain the mechanical integrity of electrodes during cycling. Therefore, even with a low binder content, the anode still shows an initial discharge capacity of 2, 973 mAh·g⁻¹ and Coulombic efficiency of 81.5%, and retains 75% at a current density of 600 mA·g⁻¹ after 100 cycles. The present organic-inorganic hybrid mineral binder may open a new approach for designing more effective polymer binders for Si-based lithium-ion batteries.

In the current study, Nafion is adopted as a dispersant for assisting the water-phase exfoliation of MoS₂. The completely ionized hydrophilic sulfonic groups and hydrophobic polytetrafluoroethylene backbone permit strong non-covalent bonding interactions between Nafion and exfoliated nanosheets for stabilization and functionalization to obtain Nafion–modified MoS₂ (N-MoS₂) nanocomposites. These interactions are stable in different pH environments. The concentration of Nafion influences the exfoliation efficiency and the size of the exfoliated nanosheets. N–MoS₂/Nafion composite membranes are prepared. The N-MoS₂ nanocomposite exhibits good dispersibility in a Nafion matrix, benefitting from the functionalization of Nafion. The N-MoS₂/Nafion composite membrane shows excellent near-infrared light-controllable multi-shape-memory performance with convenient operation. The Nafion-assisted water-phase exfoliation method shows good efficiency, convenient operation, environmental benignity, and broad application potential.