Moseoddershede9527

Motivated by interesting physical and chemical properties created by doping and topological quantum state, we perform the density functional theory and the Boltzmann transport equation to systematically investigate the geometric structures, stabilities, electronic structures, thermal conductivities and thermoelectric properties for Sb and its oxidations (Sb2O and SbO). The predicted lattice thermal conductivity (k L ) of Sb is 11.6 nW K-1 at 300 K, but it would fall drastically when introducing O atoms. This is mainly attributed to the strong anharmonic interactions by adding O atoms, and few contributions are from the decreasing phonon group velocities caused by the compressed phonon spectrum. SbO has been proven as a topological insulator with a relatively large topological band gap (E g ) ∼ 0.156 eV, and meanwhile its carrier mobilities (345.78 cm2/Vs for electrons) and scattering time (44.27 × 10-14 s for electrons) are also rather high among all 2D materials, exhibiting the excellent thermoelectric performance. The calculated maximum thermoelectric figure of merit ([Formula see text]) of the three Sb films for optimum n-type doping are close to each other at 300 K, but with an increasing temperature, the [Formula see text] of Sb for optimum n-type doping climbs quickly and can reach up to 0.73 at 700 K, which is far higher than others. More interestingly, the [Formula see text] of SbO can be increased sharply at 300 K after considering spin-orbit coupling (SOC) 0.50 for optimum p-type doping and 0.41 for optimum n-type doping. However, only the tiny changes in the [Formula see text] of Sb can be found before and after considering SOC. Our research reveals how the doping and the topological quantum state affect thermoelectric performances, providing reference to design and search high [Formula see text] thermoelectric materials in future.Silver phosphate (Ag3PO4, APO) has attracted intense attention as a visible-light-driven photocatalyst, but its large-scale application is limited by severe charge recombination and inevitable photo-corrosion. Various rational APO-based heterostructures composed of APO nanoparticles (NPs) and band-matched semiconductor support are designed to address the above issues. Nevertheless, the size, density, stability, and dispersion of APO NPs are critical challenges for the photocatalytic performance of APO-based photocatalysts. Here, three-dimensional (3D) self-assembled TiO2 hierarchical spheres (THS) prepared by a simple one-step hydrothermal method are employed as innovative support, and ultrafine high-density APO NPs with an average size of about 3 nm are successfully deposited and uniformly dispersed throughout THS to form hierarchical THS/APO composites. The novel THS/APO microstructure provides abundant reactive sites for photocatalytic reactions and promotes the photogenerated charge separation and transfer due to the ultrafine size of APO NPs and the TiO2/APO Type-II heterojunction. As a result, the THS/APO composites show significant improvement in photocatalytic activity and stability in methylene blue (MB) degradation. The reaction constant of THS/APO composites far exceeds that of either THS or APO, roughly 16 and 7 times higher than that of THS and APO under full-spectrum light, and 41 and 4 times higher under visible light. Our results strongly suggest new insights into the low-cost, large-scale application of high-efficiency APO-based photocatalyst.Full static x-ray computed tomography (CT) technology has enabled higher precision and resolution imaging and has been applied in many applications such as diagnostic medical imaging, industrial inspection and security screening. In this technique, the x-ray source section is mainly composed of a thermionic cathode and electron beam scanning system. However, they have several shortcomings such as limited scanning angle, long response time and large volume. Distributed and programmable cold cathode (i.e. carbon nanotubes, ZnO nanowires (NWs)) field-emission x-ray sources are expected to solve these problems. However, there have been several long-standing challenges to the application of such cold field emitters for x-ray sources, such as the short lifetime and rigorous fabrication process, which have fundamentally prevented their widespread use. Here, we propose and demonstrate a cold field-emission x-ray source based on a graphene oxide (GO)-coated cuprous sulfide nanowire (Cu2S NW/GO) cathode. The proposed Cu2S NW/GO x-ray source provides stable emission (>18 h at a direct voltage of 2600 V) and has a low threshold (4.5 MV m-1 for obtaining a current density of 1 μA cm-2), benefiting from the demonstrated key features such as in situ epitaxy growth of Cu2S NWs on Cu, nanometer-scale sharp protrusions within GO and charge transfer between the Cu2S NWs and GO layer. Our research provides a simple and robust method to obtain a high-performance cold field emitter, leading to great potential for the next generation of x-ray source and CT.Modulating the n- and p-type interfacial charge transport properties of the metal-semiconductor interface is vital to realizing high performance two-dimensional material nanodevices and is still a significant challenge. Here, a boron nitride (BN)-graphene lateral heterostructure (LH) was used as the interfacial tunneling layer to control the Schottky barrier, Fermi level pinning and charge injection efficiency of the metal-MoS2 interface. The BN-graphene LH with graphene-N junction structure decreased the n-type vertical Schottky barrier and enhanced the interfacial tunneling probability, while the graphene-B junction structure decreased the p-type vertical Schottky barrier. Consequently, the n-type Au/LH-MoS2 interface with Ohmic character and high tunneling probability (∼0.242) and the p-type vertical Schottky barrier of about 0.20 eV for the Pt/LH-MoS2 interface were achieved. DNA Damage inhibitor Compared to other reported BN or graphene tunneling layers, such a BN-graphene LH tunneling layer not only suppressed the charge scattering from the metal electrode to the MoS2 layer and the Fermi level pinning effect, but also reduced the contact resistance between metal electrode and tunneling layer. The underlying mechanisms were revealed to be due to the charge transfer, orbitals and interfacial dipole. This work improves the current understanding of the metal-MoS2 interface and proposes a new way to overcome the current severe contact issues for future nanoelectronic and optoelectronic applications.Silicon-based photodetectors as the main force in visible and near-infrared detection devices have been deeply embedded in modern technology and human society, but due to the characteristics of silicon itself, its response wavelength is generally less than 1100 nm. It is an interesting study to combine the state-of-art silicon processing with emerging infrared-sensitive Lead sulfide colloidal quantum dots (PbS-CQDs) to produce a photodetector that can detect infrared light. Here, we demonstrated a silicon-compatible photodetector that could be integrated on-chip, and also sensitive to infrared light which is owing to a PbS-CQDs absorption layer with tunable bandgap. The device exhibit extremely high gain which reaches maximum detectivity [Formula see text], fast response 211/558 μs, and extremely high external quantum efficiency [Formula see text], which is owing to new architecture and reasonable ligand exchange options. The performance of the device originates from the new architecture, that is, using the photovoltaic voltage generated by the surface of PbS-CQDs to change the width of the depletion layer to achieve detection. Besides, the performance improvement of devices comes from the addition of PbS-CQDs (Ethanedithiol treated) layer, which effectively reduces the fall time and makes the device expected to work at higher frequencies. Our work paves the way for the realization of cost-efficient high-performance silicon compatible infrared optoelectronic devices.Carbon nanostructures used as the active channel material in field effect transistors (FETs) are appealing in microelectronics for their improved performance, such as their high speed and low energy dissipation. However, these devices require the incorporation of nanostructure transfer steps in the fabrication process flow, which makes their application difficult in large scale integrated circuits. Here we present a novel method for the fabrication of FETs with nanostructured carbon in the channel with p-type semiconducting properties and intermediate drain-source current (IDS ) on/off ratio. The method is based on the use of Ni nanoparticles in the source-drain gap region as the seed material for the formation of carbon nanostructures in the FET channel. FETs without Ni nanoparticles in the channel showed no modulation of IDS as a function of gate voltage. The device fabrication process does not require any carbon nanostructure transfer steps since it directly forms carbon nanostructures electrically connected to the device's source and drain electrodes via electron-beam evaporation of carbon and conventional lithographic processes. Since all device fabrication steps are compatible with existing Si technology processes, they are capable of being further optimized following process development protocols practiced by the semiconductor industry.Development of perpendicular magnetic anisotropy thin films is a requisite for many applications. In this work, we have illustrated the enhancement of the PMA of Hard (Co)/Soft (Permalloy, Py) ferromagnetic bilayers by depositing them onto nanoporous anodic alumina membranes with different hole diameters varying in the range between 30 nm and 95 nm. A dramatic change in the hysteresis loops behaviour with hole size, D, and magnetic surface cover ratio parameters has been observed (1) for samples with small antidot hole diameters, the in-plane (INP) hysteresis loops show single-step magnetic behaviour; (2) for D = 75 nm, the hysteresis loops of Co/Py and Py samples exhibit a multistep magnetic behaviour; (3) a decreasing coercivity in the INP hysteresis loops for antidot arrays samples with D> 75 nm has been detected as a consequence of the reduction of the INP magnetic anisotropy and the rising of the out-of-plane component. A crossover of the magnetic anisotropy from the INP to out-of-plane for bilayer antidot samples has been observed for Co/Py ferromagnetic bilayers, favoured by the interfacial exchange coupling between the two ferromagnetic materials. These findings can be of high interest for the development of novel magnetic sensors and for perpendicular-magnetic recording patterned media based on template-assisted deposition techniques.Protein-based nanoparticles have developed rapidly in areas such as drug delivery, biomedical imaging and biocatalysis. Ferritin possesses unique properties that make it attractive as a potential platform for a variety of nanobiotechnological applications. Here we synthesized magnetoferritin (P-MHFn) nanoparticles for the first time by using the human H chain of ferritin that was expressed by Pichia pastoris (P-HFn). Western blot results showed that recombinant P-HFn was successfully expressed after methanol induction. Transmission electron microscopy (TEM) showed the spherical cage-like shape and monodispersion of P-HFn. The synthesized magnetoferritin (P-MHFn) retained the properties of magnetoferritin nanoparticles synthesized using HFn expressed by E. coli (E-MHFn) superparamagnetism under ambient conditions and peroxidase-like activity. It is stable under a wider range of pH values (from 5.0 to 11.0), likely due to post-translational modifications such as N-glycosylation on P-HFn. In vivo near-infrared fluorescence imaging experiments revealed that P-MHFn nanoparticles can accumulate in tumors, which suggests that P-MHFn could be used in tumor imaging and therapy.