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Aligned multi-walled carbon nanotubes (MWCNTs)/polyvinyl alcohol composite films were prepared by using an easy and controllable electrospinning-in situ film-forming (EF) technique. A high dielectric constant (k), a low dielectric loss, a consistently high breakdown strength, and a high energy density were obtained by using this technique. The dramatically improved dielectric properties are ascribed to the good dispersion and alignment of MWCNTs in the matrix, facilitating the formation of a large number of separated nano-capacitors (high k and low direct current (DC) conductance). For comparison purposes, the same composite films were prepared by solution casting (SC). At the same MWCNT content, the SC method yielded a higher k, but a significantly higher dielectric loss and much lower breakdown strength and energy density because of the random dispersion of MWCNTs in the matrix and the formation of a MWCNT network, which result in a large increase in DC conductance. The formation mechanism of the different microstructures and the relationships between the microstructures and dielectric properties are clarified. Our results indicate that high-performance MWCNTs/polymer dielectric composites can be obtained by controlling the microstructure of the composites by using the EF technique, which widens the applications of dielectric materials.

Rational design of a transition metal layered double hydroxide (LDH) and graphene composite is vitally important for designing high-performance supercapacitor electrodes. Although various methods are performed, the realization of high-performance is still impeded by the agglomeration of graphene and layered double hydroxide. Here, metal-organic framework derived cobalt-cobalt layered double hydroxide (Co-Co LDH) hollow nanocages, uniformly deposited on graphene nanosheets, are fabricated through facile in situ co-deposition and thermal ion-exchange reaction. Electrochemical investigation reveals that Co-Co LDH/15 mg graphene is rather outstanding, which delivers high specific capacitance of 1205 F g , excellent rate capability (60.3 % capacitance retention is obtained after the current density increased 6.67 times), and cycling stability. The excellent performance of electrode is also confirmed by assembling an asymmetric supercapacitor, which delivers high energy density of 49.5 Wh kg as well as the maximum power density of 7000 W kg . The Co-Co LDH/graphene composite proves a promising concept for constructing hierarchical structure materials in the future.

Gd3+ and Yb3+ co-doped LDH monolayer nanosheets are developed via a facile “bottom-up” method and exhibit excellent drug loading capacity for tri-mode imaging guided cancer therapy.

Halide perovskites are excellent catalysts for photocatalytic hydrogen (H2) evolution; however, their instability in aqueous systems limits their applications. In this study, an alternative system is presented to avoid the ionization of halide perovskites based on ethanol splitting and three Bi‐based halide perovskite nanosheets (Cs3Bi2X9 PNs; X = I, Br, Cl) are prepared for H2 evolution. Small amounts of these halide perovskites possess good stability in ethanol, where the optimal Cs3Bi2I9 PNs exhibit the highest H2 evolution rate of 2157.8 µmol h−1 g−1. In particular, the effects of halogen regulation on the H2 evolution activity are investigated in depth from various perspectives for Cs3Bi2X9. The increased number of halogen atoms reduces the Bi···Bi distance in the octahedral configuration and eliminates the strong localization of electron–hole pairs, which are conducive to photogenerated charge separation and transfer. In addition, the dominant contribution of halogens to the conduction band is enhanced with an increase in the halogen atomic number. This study establishes a novel strategy for studying Bi‐based perovskites for optimizing their photocatalytic properties. Furthermore, it provides a new perspective for developing highly efficient and stable H2 evolution systems for halide perovskites.

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In situ growth of Ni–Co layered double hydroxides on graphene nanosheets by virtue of metal–organic framework as a sacrifice template is reported, which yields hollow nanocages uniformly deposited on graphene nanosheets. The strong impact of graphene amount on the electrochemical performance of Ni–Co layered double hydroxides is illustrated. Controlling the mass of graphene (15 mg) leads to a maximum specific capacitance of 1265 F g–1, high rate capability (50% capacitance retention after increasing current density ten times), and good cycling life (92.9% capacitance retention after 2000 circles). The combination of battery-type Ni–Co LDH hollow nanocages/graphene composite and active carbon allows for the excellent electrochemical performance measured in an asymmetric device. In detail, the assembled asymmetric supercapacitor is able to deliver maximum specific capacitance 170.9 F g–1 in a potential window of 0–1.7 V, high energy density (68.0 Wh kg–1), as well as excellent power output (4759 W kg–1). These electrochemical performances, in combination with its facile fabrication, render hollow Ni–Co LDH/graphene composite as a promising electrode material in a sustainable energy storage device.