Urchin-shaped NiCo 2 Se 4 (u-NCSe) nanostructures as efficient sulfur hosts are synthesized to overcome the limitations of lithium-sulfur batteries (LSBs). u-NCSe provides a beneficial hollow structure to relieve volumetric expansion, a superior electrical conductivity to improve electron transfer, a high polarity to promote absorption of lithium polysulfides (LiPS), and outstanding electrocatalytic activity to accelerate LiPS conversion kinetics. Owing to these excellent qualities as cathode for LSBs, S@u-NCSe delivers outstanding initial capacities up to 1403 mAh g −1 at 0.1 C and retains 626 mAh g −1 at 5 C with exceptional rate performance. More significantly, a very low capacity decay rate of only 0.016% per cycle is obtained after 2000 cycles at 3 C. Even at high sulfur loading (3.2 mg cm −2 ), a reversible capacity of 557 mAh g −1 is delivered after 600 cycles at 1 C. Density functional theory calculations further confirm the strong interaction between NCSe and LiPS, and cytotoxicity measurements prove the biocompatibility of NCSe. This work not only demonstrates that transition metal selenides can be promising candidates as sulfur host materials, but also provides a strategy for the rational design and the development of LSBs with long-life and high-rate electrochemical performance.

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Aqueous Zn-ion batteries (AZIBs) have been recognized as promising energy storage devices due to their high theoretical energy density and cost-effectiveness. However, side reactions and Zn dendrite generation during cycling limit their practical application. Herein, ammonium acetate (CH 3 COONH 4 ) is selected as a trifunctional electrolyte additive to enhance the electrochemical performance of AZIBs. Research findings show that NH 4 + (oxygen ligand) and CH 3 COO -(hydrogenligand) with preferential adsorption on the Zn electrode surface can not only hinder Zn anode directly contact with active H 2 O, but also regulate the pH value of the electrolyte, thus suppressing the parasitic reactions. Additionally, the formed SEI is mainly consisted of Zn 5 (CO 3 ) 2 (OH) 6 with a high Zn 2+ transference number, which could achieve a dendrite-free Zn anode by homogenizing Zn deposition. Consequently, the Zn||Zn symmetric batteries with CH 3 COONH 4 -based electrolyte can operate steadily at an ultrahigh current density of 40 mA cm -2 with a cumulative capacity of 6880 mAh cm -2 , especially stable cycling at −10 °C. The assembled Zn||MnO 2 full cell and Zn||activated carbon capacitor also deliver prominent electrochemical reversibility. This work provides unique understanding of designing multi-functional electrolyte additive and promotes a long lifespan at ultrahigh current density for AZIBs.

A vertical electric field-modulated data storage device based on bilayer InSe.

In this work, high quality iron hexacyanoferrate nanocubes (HQ-PB NCs) were synthesized through a simple hydrothermal method and then investigated as cathode electrode materials for aqueous sodium-ion batteries (SIBs), which displayed a much enhanced electrochemical performance compared with the PB nanoparticles with low quality (LQ-PB NPs). The HQ-PB NCs could be promising cathode materials for aqueous SIBs.

In the wake of the considerable investigation of two-dimensional (2D) materials, van der Waals (vdW) heterostructures based on atomically thin 2D materials show large potential for functional electronic devices. Within the heterostructure, the contact barrier at the interface between two components directly affects the performance of the heterostructure. Here, by means of first-principle calculations, we took 2D graphene/InSe as a model to investigate the electronic properties and the contact behavior of a 2D metal–semiconductor contacting vdW heterostructure. We showed that there is an Ohmic contact between these two monolayers. It is highlighted that the band alignment between the two compounds can be effectively tuned by changing their interlayer distance. As a result, controllable types of contact in the graphene/InSe vdW heterostructure can be achieved, which is highly desirable for electronic and optoelectronic devices. Furthermore, nonequilibrium Green’s function simulations demonstrate that the graphene/InSe heterostructure shows a distinguished photogenerated current. Our results may supply useful information for designing novel, high-performance electronic and optoelectronic devices based on van der Waals heterostructures.

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Isoelectronic co-dopants enhance the photocatalytic hydrogen production properties without affecting the band gap feature of pure black phosphorene.