Ultrathin Metal–Organic Framework Nanosheets with Ultrahigh Loading of Single Pt Atoms for Efficient Visible‐Light‐Driven Photocatalytic H2 Evolution

A surfactant‐stabilized coordination strategy is used to make two‐dimensional (2D) single‐atom catalysts (SACs) with an ultrahigh Pt loading of 12.0 wt %, by assembly of pre‐formed single Pt atom coordinated porphyrin precursors into free‐standing metal–organic framework (MOF) nanosheets with an ultrathin thickness of 2.4±0.9 nm. This is the first example of 2D MOF‐based SACs. Remarkably, the 2D SACs exhibit a record‐high photocatalytic H₂ evolution rate of 11 320 μmol g^?1 h^?1 via water splitting under visible light irradiation (λ>420 nm) compared with those of reported MOF‐based photocatalysts. Moreover, the MOF nanosheets can be readily drop‐casted onto solid substrates, forming thin films while still retaining their photocatalytic activity, which is highly desirable for practical solar H₂ production.     

Rational Design of Cellulose Nanofibrils Separator for Sodium-Ion Batteries

Cellulose nanofibrils (CNF) with high thermal stability and excellent electrolyte wettability attracted tremendous attention as a promising separator for the emerging sodium-ion batteries. The pore structure of the separator plays a vital role in electrochemical performance. CNF separators are assembled using the bottom-up approach in this study, and the pore structure is carefully controlled through film-forming techniques. The acid-treated separators prepared from the solvent exchange and freeze-drying demonstrated an optimal pore structure with a high electrolyte uptake rate (978.8%) and Na⁺ transference number (0.88). Consequently, the obtained separator showed a reversible specific capacity of 320 mAh/g and enhanced cycling performance at high rates compared to the commercial glass fiber separator (290 mAh/g). The results highlight that CNF separators with an optimized pore structure are advisable for sodium-ion batteries.     

Multifunctional waterproof MXene-coated wood with high electromagnetic shielding performance

Increasing electromagnetic pollution calls for electromagnetic interference (EMI) shielding materials, especially sustainable, lightweight, and environmentally stable, biomass-based materials. MXene-coated wood (M/wood) is prepared by simply spraying MXene sheets on the wood surface. Varying this spray coating manipulates the shielding performance and its application to different wood species. The M/wood exhibits high electrical conductivity (sheet resistance is only 0.65 Ω/sq) with an excellent EMI shielding effectiveness of 31.1 dB at 8.2?~?12.4 GHz and is also fire retardant. Furthermore, waterborne acrylic resin (WA) is coated on M/wood to enhance environmental stability. The WA coating improves EMI shielding performance stability after water-soaking and drying testing and prevents the peeling of MXene from wood. These satisfactory properties of WA-M/wood and the facile manufacturing approach promote the feasibility of wood-based EMI shielding materials.

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Insight into the Molecular Mechanism for Enhanced Longevity of Supramolecular Vesicular Photocatalysts

Supramolecular self-assembly is a promising strategy for stabilizing the photo-sensitive components in photocatalysis. However, the underlying correlation between the enhanced photostability and supramolecular structure at the molecular level has not yet been fully understood. Herein, we develop a biomimetic vesicular membrane-based polyporphyrin photocatalyst exhibiting excellent photocatalytic stability with at least activity time of 240 h in hydrogen generation. Time-domain ab initio modelling together with transient absorption spectroscopy, visual frontier orbitals and Gibbs free energy calculation disclose that the ordered aggregation of porphyrin units in the vesicle membrane facilitates “hot” electron relaxation and the rapid dissipation of photo-generated charges, thereby contributing to the longevity. This work deepens the molecular-level understanding on photostability and photocatalytic mechanism of supramolecular photocatalysts.