Recently, nanostructured materials have attracted great interest in the field of lithium-ion batteries, essentially because of their substantial advantages, such as short transport path lengths for both electrons and Li + ions, a large amount of contact surface area between the electrode and electrolyte, and large flexibility and toughness for accommodating strain introduced by Li + insertion/extraction. [1][2][3] Among the transition-metal oxides, nanostructured MoO 3 has been extensively investigated as a key material for fundamental research and technological applications in optical devices, smart windows, catalysts, sensors, lubricants, and electrochemical storage. [4][5][6][7] There are two basic polytypes of One might take advantage of the intrinsic structural anisotropy of a-MoO 3 for tuning its properties by interlayer structural modification, annealing, and lithiation. [5,8,9] In this Communication, we report the electroactivity of a-MoO 3 nanobelts after lithiation that show superior performance to nonlithiated a-MoO 3 nanobelts. An X-ray diffraction (XRD) measurement was performed using a D/MAX-III X-ray diffractometer. Fourier-transformed infrared (FTIR) absorption spectra were recorded using the 60-SXB IR spectrometer. Raman spectra were taken using a Renishaw RM-1000 laser Raman microscopy system. Scanning electron microscopy (SEM) images were collected with a JSM-5610 and FES-EM LEO 1530. Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) were recorded by using a JEOL JEM-2010 FEF microscope. The electrochemical properties were studied with a multichannel battery testing system. Batteries were fabricated using a lithium pellet as the negative electrode; 1 M solution of LiPF 6 in ethylene carbon (EC)/dimethyl carbonate (DMC) as the electrolyte; and a pellet made of the nanobelts, acetylene black and PTFE in a 10:7:1 ratio as the positive electrode. The fabrication of a single nanobelt-based device has been described in detail elsewhere. [10] XRD measurement was first used to study the phase and lattice modification of the nanobelts before and after lithiation (Fig. 1A). The diffraction peaks of the XRD pattern for both samples can be readily indexed to be orthorhombic with lattice constants of a = 3.962 Å, b = 13.85 Å, c = 3.697 Å (International Centre for Diffraction Data (ICDD) No. . No peaks of any other phases were detected, indicating the high purity of the MoO 3 nanobelts. For the non-lithiated MoO 3 nanobelts, the stronger intensities of (020), (040), and (060) peaks than those for the bulk MoO 3 (Fig. S1, Supporting Information) indicates the anisotropic growth of the nanostructure as well as the preferred orientation of the nanobelts on the substrate. Importantly, in comparison to the nonlithiated sample, there is a small shift of the (020) peak toward a lower diffraction angle for the lithiated sample. This is direct evidence of an expanded b-plane interlayer distance for 0.065 Å after lithiation, ...

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In this work, a facile route using a simple solvothermal reaction and sequential calcinations to synthesize porous R-Fe 2 O 3 flower-like nanostructures without employing templates or matrices for self-assembly is presented. The flower-like nanostructures are composed of nanosheets with a thickness of about 20 nm, which are characterized by field-emission scanning electron microscopy (FESEM). Influencing factors such as the dosage of reactants and the solvents are systematically investigated. A possible formation mechanism for the flower-like nanostructure is proposed. A BET test shows that the product is porous and has a large surface area. The electrochemical, magnetic, and photocatalytic properties of the as-obtained R-Fe 2 O 3 3D nanostructure are systematically investigated. The result shows that these properties are greatly affected by the porous structure.

A new wurtzite (WZ) structure CuInS 2 , space group P6 3 mc, a ) 3.90652(13) Å, c ) 6.42896(23) Å, has been synthesized by a one-step solvothermal method. Analogous with the disordered zinc-blende structure, wurtzite structure is metastable at room temperature and considered as a disordered polymorph of chalcopyrite (CH) structure, where Cu and In atoms randomly occupy the cation sublattice positions. It is believed that the solvent of ethanolamine plays an important role in the synthesis of WZ-CuInS 2 . The coordination between Cu 2+ and -NH 2 of ethanolamine molecules favors the nucleation and growth of WZ-CuInS 2 . Differential scanning calorimeter, together with X-ray diffraction analysis, revealed a phase transition from WZ-CuInS 2 to CH-CuInS 2 when WZ-CuInS 2 was heated to certain temperature. The visible and near-infrared absorption spectra show that the as-prepared nanostructured WZ-CuInS 2 has distinct optical properties compared with conventional CH-CuInS 2 .

Resistive random access memory (RRAM) devices are receiving increasing extensive attention due to their enhanced properties such as fast operation speed, simple device structure, low power consumption, good scalability potential and so on, and are currently considered to be one of the next-generation alternatives to traditional memory. In this review, an overview of RRAM devices is demonstrated in terms of thin film materials investigation on electrode and function layer, switching mechanisms and artificial intelligence applications. Compared with the well-developed application of inorganic thin film materials (oxides, solid electrolyte and two-dimensional (2D) materials) in RRAM devices, organic thin film materials (biological and polymer materials) application is considered to be the candidate with significant potential. The performance of RRAM devices is closely related to the investigation of switching mechanisms in this review, including thermal-chemical mechanism (TCM), valance change mechanism (VCM) and electrochemical metallization (ECM). Finally, the bionic synaptic application of RRAM devices is under intensive consideration, its main characteristics such as potentiation/depression response, short-/long-term plasticity (STP/LTP), transition from short-term memory to long-term memory (STM to LTM) and spike-time-dependent plasticity (STDP) reveal the great potential of RRAM devices in the field of neuromorphic application.

Monoclinic NH 4 V 3 O 8 single-crystalline nanobelts with widths of 80-180 nm, thicknesses of 50-100 nm, and lengths up to tens of micrometers have been synthesized at large scale in an ammonium metavanadate solution by a templates/catalysts-free route. Such nanobelts grow along the direction of [010]. The individual NH 4 V 3 O 8 nanobelt exhibits nonlinear, symmetric current/voltage (I/V) characteristics, with a conductivity of 0.1-1 S/cm at room temperature and a dielectric constant of ∼130. The dominant conduction mechanism is based on small polaron hopping due to ohmic mechanism at low electric field below 249 V/cm due to Schottky emission at medium electric field between 249 and 600 V/cm and due to the Poole-Frenkel emission mechanism at high field above 600 V/cm.

A facile and green hydrothermal method has been developed to fabricate three-dimensional nanoarchitecture composites consisting of MoO2 nanoparticles decorated on the graphene oxide (GO). The composites were characterized by XRD, SEM, and HRTEM. It was demonstrated that MoO2 nanoparticles are 5–15 nm in size and homogeneously dispersed on GO and denoted as MoO2-GO composites. When tested as an anode material for lithium-ion batteries, the MoO2-GO composites exhibited an improved storage capacity and cycling performance, higher than the pure MoO2 nanoparticles. As a result, the GO effectively forms a conductive network that greatly enhances the electrical conductivity and structural stability of composites. The incorporation of the flexible and conductive GO and the small homogeneous MoO2 nanoparticles could not only maintain the structural and electrical integrity, but also accommodate the volume change during the lithium-ion intercalation and de-intercalation. The ultrafine MoO2 nanoparticles dispersed on the GO are beneficial to the improved electrochemical performance of the composites, which makes them a promising anode candidate for lithium-ion batteries.