We report the synthesis of single‐phase Bi3O2S3 sample and confirm the occurrence of bulk superconductivity with transition temperature at 5.8 K. The Bi3O2S3 superconductor is categorized as typical type‐II superconductor based on the results of both temperature and magnetic field dependences of magnetization. Hall coefficient measurements give evidence of a multiband character, with a dominant conduction mainly by electron‐like charge carriers. The charge carrier density is about 1.45 × 1019 cm–3, suggesting that the system has very low charge carrier density.
Bismuth sulfide nanorod array is directly grown on nickel foam (R‐Bi2S3/NF) to serve as a completely carbon and binder‐free 3D porous oxygen electrode material for lithium‐oxygen (Li‐O2) batteries. The synergistic effect of the fast kinetics of electron transport and gas and electrolyte diffusion provided by the continuous free‐standing network structure and the excellent electrocatalytic activity of the bismuth sulfide nanorod array enables outstanding performance of the oxygen electrode. Li‐O2 battery with the free‐standing R‐Bi2S3/NF oxygen electrode exhibits high energy efficiency (78.7%), good rate capability (4464 mA h g−1 at 1500 mA g−1), as well as excellent cyclability (146 cycles) while maintaining a moderate specific capacity of 1000 mA h g−1. The effect of cathodes with different reactant (O2) and intermediate (LiO2) adsorbability on the product (Li2O2) growth model is studied by first‐principle calculations. The strong O2 adsorption and weak LiO2 adsorption on Bi2S3 drives the growth of large‐size Li2O2 particles via solution growth model. Remarkably, the large‐area pouch‐type Li‐O2 battery delivers an energy density of 330 Wh kg−1. The present results open up a promising avenue toward developing novel electrode architecture for high‐performance Li‐O2 batteries through controlling morphology and functionality of porous electrodes. 相似文献
The search of new high-mobility two-dimensional (2D) semiconductors is crucial for the development of next-generation photodetectors, since current photodetectors based on single 2D semiconductors usually cannot simultaneously own ultrafast response rate and ultrahigh sensitivity. Here, using a facial method of sequentially oxidizing Bi2Se3 at optimal O content, a series of bismuth oxyselenide semiconductors (Bi3O2.5Se2, Bi2O2Se, Bi2SeO5) with appealing electronic applications are successfully synthesized. The crystal and band structures of a superlattice-free Bi3O2.5Se2 phase are resolved by 3D electron diffraction and density functional theory calculations, showing a unique non-neutral layered structure, moderate band gap, and small effective mass. More importantly, the concept of Bi2Se3 + O2 can be extended to synthesize the superlattice-free Bi3O2.5Se2 ultrathin films by chemical vapor deposition, whose room-temperature mobility can be as high as ≈150 cm2 V−1 s−1 based on Hall measurements. The ultrathin Bi3O2.5Se2 photodetectors with a simple device configuration simultaneously own ultrafast response time (≈31 µs), ultrahigh responsivity (≈8 × 104 A/W), and large detectivity (≈8 × 1013 Jones). This work not only introduces a facile way to regulate the phase in the bismuth oxyselenide family, but also provides an alternative candidate for ultrafast and ultrasensitive photodetectors. 相似文献
With a series of 1.0 wt%Bi$_{2}$O$_{3}$-$x$ wt% CuO ($x =0.0$, 0.2, 0.4, 0.6, and 0.8) serving as sintering additives, Ni$_{0.23}$Cu$_{0.32}$Zn$_{0.45}$Fe$_{2}$O$_{4}$ ferrites are successfully synthesized at a low temperature (900 $^\circ$C) by using the solid state reaction method. The effects of the additives on the phase formation, magnetic and dielectric properties as well as the structural and gyromagnetic properties are investigated. The x-ray diffraction (XRD) results indicate that the added Bi$_{2}$O$_{3}$-CuO can lower the synthesis temperature significantly without the appearing of the second phase. The scanning electron microscope (SEM) images confirm that Bi$_{2}$O$_{3}$ is an important factor that determines the sintering behaviors, while CuO affects the grain size and densification. With CuO content $x=0.4$ or 0.6, the sample shows high saturation magnetization, low coercivity, high real part of magnetic permeability, dielectric permittivity, and small ferromagnetic resonance linewidth ($\Delta H$). The NiCuZn ferrites are a promising new generation of high-performance microwave devices, such as phase shifters and isolators. 相似文献
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