Boron Nitride Nanosheets Strengthened PVA/Borax Hydrogels with Highly Efficient Self-Healing and Rapid pH-Driven Shape Memory Effect

Self-healing hydrogels often possess poor mechanical properties which largely limits their applications in many fields. In this work, boron nitride nanosheets are introduced into a network of the poly(vinyl alcohol)/borax (PVA/borax) hydrogels to enhance the mechanical properties of the hydrogel without compromising the self-healing abilities. The obtained hydrogels exhibit excellent mechanical properties with a tensile strength of 0.410 ± 0.007 MPa, an elongation at break of 1712%, a Young's Modulus of 0.860 ± 0.023 MPa, and a toughness of 3.860 ± 0.075 MJ m⁻³. In addition, the self-healing efficiency of the hydrogels is higher than 90% within 10 min at room temperature. Benefiting from the excellent self-healing properties, the shapeability of the hydrogel fragments is observed using different molds. In addition, the hydrogels display rapid pH-driven shape memory effects and can recover to their original shape within 260 s. Overall, this work provides a new approach to hydrogels with integrated excellent mechanical properties, self-healing abilities, and rapid pH-driven shape memory effects.     

Study on the graphite nanosheets/resin shielding coatings

Shielding coatings based on graphite nanosheets were prepared by compounding method. The surface morphology of the graphite nanosheets and conductive coatings was examined by scanning electron microscopy. The surface resistivity of the coatings was greatly declined by incorporating the graphite nanosheets. The electromagnetic interference shielding effectiveness (SE) from 0.3 MHz to 1.5 GHz was also studied, and found that the SE of the coatings was consistent with its conductivity. The best sample was shown to exhibit up to 38 dB of SE at 1.5 GHz (with a thickness of 400 μm). The main shielding mechanism of the system was reflection and multiple reflections.     

Ultrathin Co3O4 nanosheets highly dispersed on reduced graphene oxide: An efficient bi-functional catalyst for Li-O2 battery

Ultrathin Co₃O₄ nanosheets grown on the reduced graphene oxide (Co₃O₄/rGO) was synthesized by a simple hydrothermal method and was investigated as a cathode in a Li-O₂ battery. Benefited from the synergistic effect between Co₃O₄ and rGO, the hybrid exhibits a high initial capacity of 10,528 mAh g^?1 along with a high coulombic efficiency (84.4%) at 100 mA g^?1. In addition, the batteries show an enhanced cycling stability and after 113 cycles, the cut-off discharge voltage remains above 2.5 V. The outstanding performance is intimately related to the high surface area of rGO, which not only provide carbon skeleton for the uniform distribution of Co₃O₄ nanosheets but also facilitate the reversible formation and decomposition of insoluble Li₂O₂. The results of electrochemical tests confirm that the Co₃O₄/rGO hybrid is a promising candidate for the Li-O₂ batteries.     

Reducing Hysteresis and Enhancing Performance of Perovskite Solar Cells Using Low‐Temperature Processed Y‐Doped SnO2 Nanosheets as Electron Selective Layers

Despite the rapid increase of efficiency, perovskite solar cells (PSCs) still face some challenges, one of which is the current–voltage hysteresis. Herein, it is reported that yttrium‐doped tin dioxide (Y‐SnO₂) electron selective layer (ESL) synthesized by an in situ hydrothermal growth process at 95 °C can significantly reduce the hysteresis and improve the performance of PSCs. Comparison studies reveal two main effects of Y doping of SnO₂ ESLs: (1) it promotes the formation of well‐aligned and more homogeneous distribution of SnO₂ nanosheet arrays (NSAs), which allows better perovskite infiltration, better contacts of perovskite with SnO₂ nanosheets, and improves electron transfer from perovskite to ESL; (2) it enlarges the band gap and upshifts the band energy levels, resulting in better energy level alignment with perovskite and reduced charge recombination at NSA/perovskite interfaces. As a result, PSCs using Y‐SnO₂ NSA ESLs exhibit much less hysteresis and better performance compared with the cells using pristine SnO₂ NSA ESLs. The champion cell using Y‐SnO₂ NSA ESL achieves a photovoltaic conversion efficiency of 17.29% (16.97%) when measured under reverse (forward) voltage scanning and a steady‐state efficiency of 16.25%. The results suggest that low‐temperature hydrothermal‐synthesized Y‐SnO₂ NSA is a promising ESL for fabricating efficient and hysteresis‐less PSC.     

A Cost‐Efficient Bifunctional Ultrathin Nanosheets Array for Electrochemical Overall Water Splitting

The design of cost‐efficient earth‐abundant catalysts with superior performance for the electrochemical water splitting is highly desirable. Herein, a general strategy for fabricating superior bifunctional water splitting electrodes is reported, where cost‐efficient earth‐abundant ultrathin Ni‐based nanosheets arrays are directly grown on nickel foam (NF). The newly created Ni‐based nanosheets@NF exhibit unique features of ultrathin building block, 3D hierarchical structure, and alloy effect with the optimized Ni₅Fe layered double hydroxide@NF (Ni₅Fe LDH@NF) exhibiting low overpotentials of 210 and 133 mV toward both oxygen evolution reaction and hydrogen evolution reaction at 10 mA cm^?2 in alkaline condition, respectively. More significantly, when applying as the bifunctional overall water splitting electrocatalyst, the Ni₅Fe LDH@NF shows an appealing potential of 1.59 V at 10 mA cm^?2 and also superior durability at the very high current density of 50 mA cm^?2.     

Ultrathin 2D Zirconium Metal–Organic Framework Nanosheets: Preparation and Application in Photocatalysis

Synthesizing ultrathin 2D metal–organic framework nanosheets in high yields has received increasing research interest but remains a great challenge. In this work, ultrathin zirconium‐porphyrinic metal–organic framework (MOF) nanosheets with thickness down to ≈1.5 nm are synthesized through a pseudoassembly–disassembly strategy. Owing to the their unique properties originating from their ultrathin thickness and highly exposed active sites, the as‐prepared ultrathin nanosheets exhibit far superior photocatalysis performance compared to the corresponding bulk MOF. This work highlights new opportunities in designing ultrathin MOF nanosheets and paves the way to expand the potential applications of MOFs.     

水热法制备片状纳米氧化镍及其光催化性能

采用水热法制备片状纳米NiO,用XRD和TEM对样品的晶型及颗粒形貌进行了表征。以蒽醌染料KN-R为对象,紫外灯为光源,研究了催化剂热处理温度、催化剂用量、光照时间、染料的初始浓度等因素对染料脱色率的影响,以及催化剂的重复利用效果。结果表明：NiO催化剂能显著降解蒽醌染料KN-R,且能重复利用,在未曝气供氧时,NiO的催化活性优于p-25 TiO2。