The 2H phase and 1T phase coexisting in the same molybdenum disulfide (MoS2 ) nanosheets can influence the electronic properties of the materials. The 1T phase of MoS2 is introduced into the 2H-MoS2 nanosheets by two-step hydrothermal synthetic methods. Two types of nonvolatile memory effects, namely write-once read-many times memory and rewritable memory effect, are observed in the flexible memory devices with the configuration of Al/1T@2H-MoS2 -polyvinylpyrrolidone (PVP)/indium tin oxide (ITO)/polyethylene terephthalate (PET) and Al/2H-MoS2 -PVP/ITO/PET, respectively. It is observed that structural phase transition in MoS2 nanosheets plays an important role on the resistive switching behaviors of the MoS2 -based device. It is hoped that our results can offer a general route for the preparation of various promising nanocomposites based on 2D nanosheets of layered transition metal dichalcogenides for fabricating the high performance and flexible nonvolatile memory devices through regulating the phase structure in the 2D nanosheets.

Uniform CoSe quantum dots (CSQDs) were successfully synthesized through a facile solvothermal method. The obtained CSQDs with average size of 3.2 ± 0.1 nm and thickness of 1.8 ± 0.2 nm were demonstrated good stability and strong fluorescence under UV light after being easily dispersed in both of N,N-dimethylformamide (DMF) and deionized water. We demonstrated the flexible resistive switching memory device based on the hybridization of CSQDs and polyvinylpyrrolidone (PVP) (CSQDs-PVP). The device with the Al/CSQDs-PVP/Pt/poly(ethylene terephthalate) (PET) structure represented excellent switching parameters such as high ON/OFF current ratio, low operating voltages, good stability, and flexibility. The flexible resistive switching memory device based on hybridization of CSQDs and PVP has a great potential to be used in flexible and high-performance memory applications.

Current-induced spin–orbit torques (SOTs) enable efficient electrical manipulation of the magnetization in heterostructures with a perpendicular magnetic anisotropy through the Rashba effect or spin-Hall effect. However, in conventional SOT-based heterostructures, an in-plane bias magnetic field along the current direction is required for the deterministic switching. Here, we report that the field-free SOT switching can be achieved by introducing a wedged oxide interface between a heavy metal and a ferromagnet. The results demonstrate that the field-free SOT switching is determined by a current-induced perpendicular effective field (H z eff) originating from the interfacial Rashba effect due to the lateral structural symmetry-breaking introduced by the wedged oxide layer. Furthermore, we show that the sign and magnitude of H z eff exhibit a significant dependence on the interfacial oxygen content, which can be controlled by the inserted oxide thickness. Our findings provide a deeper insight into the field-free SOT switching by the interfacial Rashba effect.

The Fe 3 O 4 @SiO 2 composite nanoparticles were obtained from as-synthesized magnetite (Fe 3 O 4) nanoparticles through the modified Stöber method. Then, the Fe 3 O 4 nanoparticles and Fe 3 O 4 @SiO 2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investigated. The results revealed that the Fe 3 O 4 @SiO 2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe 3 O 4 @SiO 2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.

Porous Co3O4/SnO2 quantum dot (QD) heterojunctions with a strong synergistic effect are successfully synthesized in this paper. Owing to the strong synergistic effect between Co3O4 and SnO2QDs, Co3O4/SnO2QD heterostructures possess more Co2+ ions for a faster Co2+/Co0 redox reaction in the process of sensing of reducing gases and electrochemical reactions, and more oxygen vacancies for more active sites and reduced charge transfer resistance on the surface. These advantages are demonstrated to significantly enhance the gas sensitivity to xylene and greatly improve the catalysis for the oxygen evolution reaction (OER). As a catalyst for the OER, Co3O4/SnO2QD (1 : 1) heterostructures exhibit the highest current density, lowest onset potential, largest active surface area and remarkable durability in alkaline electrolytes. The sensitivity of Co3O4/SnO2QD (1 : 1) heterostructures to 100 ppm xylene is almost 10 times higher than that of pure Co3O4 nanosheets and 3 times higher than that of SnO2QDs. In addition, Co3O4/SnO2QD (1 : 1) heterostructure sensors exhibit excellent gas selectivity, long-term stability and markedly high response to low concentrations of xylene at low operating temperatures.