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• MnO 2 was designed as flower-like structure to obtain a larger surface area. • BiOBr and Bi metals were combined with MnO 2 to construct a heterojunction. • The magnetic core facilitated the recycling of the photocatalyst. • The core-shell structure can generate synergistic effects of different components. • Composite materials exhibited excellent dyes degradation capabilities. The flower-like Fe 3 O 4 /SiO 2 /MnO 2 /BiOBr-Bi magnetic composite photocatalyst was prepared in this work. The combination of BiOBr and Bi metal with flower-like MnO 2 constituted a heterojunction structure, which increased the specific surface area of the photocatalyst and promoted the separation of photo-generated carriers, resulting in the enhanced catalytic performance. The morphologies and the compositions of the photocatalyst were characterized in detail. Under simulated light, the degradation of organic dye methylene blue (MB) was used to research the photocatalytic activity. In the case of 15 mg photocatalyst, it was found that the photocatalytic degradation efficiency to the MB solution was 95.23% within 150 min. Moreover, the degradation rate of MB could still reach 81.11% after four cycles. The design of flower-like composites with magnetic core-shell structure provided a new method for fabricating photocatalysts having excellent catalytic performance and cyclic stability. [ABSTRACT FROM AUTHOR]

Metallic lithium (Li) is considered to be one of the most promising anodes for Li-ion batteries due to its high theoretical capacity and low reduction potential. However, dendritic growth and substantial volume variations during battery operation make it difficult for commercialization. Here, a graphene and SiO 2 composites material was presented as a lithiophilic host to enable superior long-term cycling for Li-metal anode. The porous skeleton of graphene with excellent electronic conductivity can effectively reduce the actual current density and suppress the volume expansion. And the SiO 2 particles with excellent ionic conductivity can significantly suppress the growth of Li dendrites and regulate the nucleation sites. So doping SiO 2 nanoparticles between graphene sheets can significantly suppress the growth of Li dendrites and the volume expansion effect of metallic Li deposition, while also providing good electrochemical performance. Benefitting from these synergistic effects, the Li-GF@SiO 2 battery exhibits excellent electrochemical reversibility over 500 cycles depositing 1 mAh cm−2 of metallic Li at a current density of 1 mA cm−2, and the coulombic efficiency of the Li-GF@SiO 2 battery is still as high as 97%, but the Li-Cu battery decays after 75 cycles. So this hierarchical SiO 2 -microsphere-graphene host demonstrates great potential for Li batteries. • The type of graphene and SiO 2 composite material is designed for the stable host of lithium (Li) metal anode because of its lithiophilic character. • The hierarchical silica spheres can effectively reduce the actual current density and guide the nucleation of Li metal. • The superior electronic conductivity and ionic conductivity of composite materials are utilized to suppress the growth of Li dendrites and volume expansion. • The novelty lithiophilic host of Li metal anode can achieve over 500 cycles at a current density of 1 mA cm−2 for Li-metal batteries. [ABSTRACT FROM AUTHOR]

In this work, hierarchical hexagonal nanoplates NiO composite with microcrystalline graphite are successfully synthesized by a hydrothermal process. Carbon nanofibers are disaggregated to the microcrystalline graphite and they are dispersed in NiO hexagonal structure (H–NiO sample). Microcrystalline graphite (1 wt% of the composite) has effect on growth NiO hexagonal nanoplates, improving the sample conductivity and stability. At the first cycle, H–NiO sample presents a high discharge capacity of 1357.2 mAh g−1 and a charge capacity of 1002.6 mAh g−1 with an initial coulombic efficiency of 73.9%. After 45 cycles, H–NiO sample exhibits a high reversible capacity of 1111.6 mAh g−1. The lithium diffusion coefficient of the H–NiO is calculated to be 7.517 × 10−12 cm2 s−1 with faster Li+ diffusion ability than pure NiO sample. The microcrystalline graphite in the composite electrode can effectively decrease the volume change and pulverization of NiO component, meanwhile, it hinders the aggregation in the cycled electrode. The microcrystalline graphite with intrinsic stability has potential application in producing composites with other metal oxides for highly reversible lithium storage capability. The as-produced microcrystalline graphite is in-situ composite with NiO hexagonal plates and play the key role in enhancement of electrochemical properties. The H–NiO nanoplates which is supported by microcrystalline graphite exhibits an excellent cycling stability, with a high reversible capacity of 1111.6 mAh g−1 at a current density of 100 mA g−1 after 45 cycles. Image 1 • Hierarchical hexagonal nanoplates NiO with microcrystalline graphite is synthesized. • Carbon nanofibers disaggregated to microcrystalline graphite and composite with NiO. • Microcrystalline graphite plays the key role in enhanced electrochemical properties. • H–NiO nanoplates presents discharge/charge capacities of 1357.2/1002.6 mAh g−1. • H–NiO exhibit reversible capacity of 1111.6 mAh g−1 after 45 cycles. [ABSTRACT FROM AUTHOR]