Zn-doped NiSe2@Ni(OH)2 nanocomposites as binder-free electrodes for asymmetric supercapacitors with impressive performance.

The low stability and poor activities of transition metal selenides (TMSs) in alkaline electrolyte limit their application in supercapacitors. Metal doping and hybridization of various electroactive materials with different properties are utilized to enhance the electrochemical performance of TMSs by optimizing their electronic structure and providing rich electrochemical active sites. Herein, we report a simple two-step hydrothermal method for the growth of Zn-doped NiSe2 and Ni(OH)2 nanocomposites on Ni foam [Zn-NiSe2/Ni(OH)2]. The resulting material delivers high specific capacity (1525.8 C g-1/564.7 mA h g-1 at 6 A g-1 and 1220 C g-1 at 10 A g-1) in a three-electrode system. A Zn-NiSe2/Ni(OH)2//porous carbon (PC) aqueous asymmetric supercapacitor (ASC) was built by utilizing Zn-NiSe2/Ni(OH)2 as the positive electrode and PC as the negative electrode. This Zn-NiSe2/Ni(OH)2//PC ASC shows an energy density of 75.8 W h kg-1 at a power density of 916.1 W kg-1 and achieves a specific capacity retention of 100% after 25 000 cycles at 10 A g-1. These results reveal that the Zn doping and the hybridization of NiSe2 with Ni(OH)2 can obtain impressive electrochemical properties in ASCs.

Comparative Genomics Analysis of Habitat Adaptation by Lactobacillus kefiranofaciens.

Lactobacillus kefiranofaciens is often found in fermented dairy products. Many strains of this species have probiotic properties, contributing to the regulation of immune metabolism and intestinal flora. This species was added to the list of lactic acid bacteria that can be added to food in China, in 2020. However, research on the genomics of this species is scarce. In this study we undertook whole genome sequencing analysis of 82 strains of L. kefiranofaciens from different habitats, of which 9 strains were downloaded from the NCBI RefSeq (National Center for Biotechnology Information RefSeq). The mean genome size of the 82 strains was 2.05 ± 0.25 Mbp, and the mean DNA G + C content was 37.47 ± 0.42%. The phylogenetic evolutionary tree for the core genes showed that all strains belonged to five clades with clear aggregation in relation to the isolation habitat; this indicated that the genetic evolution of L. kefiranofaciens was correlated to the isolation habitat. Analysis of the annotation results identified differences in the functional genes, carbohydrate active enzymes (CAZy) and bacteriocins amongst different isolated strains, which were related to the environment. Isolates from kefir grains had more enzymes for cellulose metabolism and a better ability to use vegetative substrates for fermentation, which could be used in feed production. Isolates from kefir grains also had fewer kinds of bacteriocin than isolates from sour milk and koumiss; helveticin J and lanthipeptide class I were not found in the isolates from kefir grains. The genomic characteristics and evolutionary process of L. kefiranofaciens were analyzed by comparative genomics and this paper explored the differences in the functional genes amongst the strains, aiming to provide a theoretical basis for the research and development of L. kefiranofaciens.

MnPS3 spin-flop transition-induced anomalous Hall effect in graphite flake via van der Waals proximity coupling.

Detection of the antiferromagnetic (AFM) state is an important issue for the application of two-dimensional (2D) antiferromagnets in spintronics, and interfacial exchange coupling is a highly efficient means to detect AFM order. However, there are no experimental reports of AFM state detection in van der Waals heterostructures, based on which 2D AFM spintronics can be developed. In this paper, we report a spin flop transition (SFT)-induced anomalous Hall effect in a heterostructure of MnPS3/graphite flake (GF) through van der Waals proximity coupling. The scaling behavior study and theoretical calculations confirm that the SFT in AFM MnPS3 can generate momentum-space nonzero Berry curvature integration in the adjacent GF. Our work opens a path for the realization of AFM state detection through the proximity effect in a stacking structure, thereby promoting the application of 2D antiferromagnets in future 2D spintronics.

High Capacity and Energy Density of Zn-Ni-Co-P Nanowire Arrays as an Advanced Electrode for Aqueous Asymmetric Supercapacitor.

Developing multicomponent transition-metal phosphides has become an efficient way to improve the capacitive performance of single-component transition-metal phosphides. However, reports on quaternary phosphides for supercapacitor applications are still scarce. Here, we report high capacity and energy density of Zn-Ni-Co-P quaternary phosphide nanowire arrays on nickel foam (ZNCP-NF) composed of highly conductive metal-rich phosphides as an advanced binder-free electrode in aqueous asymmetric supercapacitors. In a three-electrode system using the new electrode, a high specific capacity of 1111 C g-1 was obtained at a current density of 10 A g-1. Analysis of this aqueous asymmetric supercapacitor with ZNCP-NF as the positive electrode and commercial activated carbon as the negative electrode reveals a high energy density (37.59 Wh kg-1 at a power density of 856.52 W kg-1) and an outstanding cycling performance (capacity retention of 92.68% after 10 000 cycles at 2 A g-1). Our results open a path for a new design of advanced electrode material for supercapacitors.