Synthesis and characterization of microstructural α-​Mn2O3 materials

Low-​dimensional α-​Mn2O3 materials with novel surface morphologies were prepd. by thermal decompn. of hydrothermal-​derived MnCO3. The powder x-​ray diffraction pattern reveals that the Mn2O3 microstructures are of cubic phase structure. From FTIR results, the peaks ≈600-​450 cm-​1 correspond to Mn-​O bending vibrations. From the TGA results, the obsd. major wt. loss ≈31​% between 350 and 540° is due to the decompn. of MnCO3 into Mn2O3. The XPS results showed that Mn is in +3 oxidn. state. The peaks at 641.2 and 652.73 eV are assigned to the Mn2p3​/2 and Mn2p1​/2 of Mn3+ states, resp. The SEM images showed that the α-​Mn2O3 products exhibit spheres, dumbbell-​, and peanut-​shaped microstructure. These microstructures are mainly composed of wires​/rods and particles. The SEM results also revealed that the obtained α-​Mn2O3 maintains the frame structure of the precursor MnCO3

Morphological Evolution of (NH4)0.5V2O5·mH2O Fibers into Belts, Triangles, and Rings

In this contribution, single-crystalline (NH4)0.5V2O5·mH2O xerogels made of belts, rings, triangles, and ovals have been synthesized using a surfactant-free hydrothermal method. The analytical techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED) have been used to characterize the morphology, composition, and structure of the as-prepared products. On the basis of SEM and TEM observations, we suggested that the as-prepared (NH4)0.5V2O5·mH2O rings, triangles, and ovals have been formed by connecting two ends of the vanadium oxide sheet made of edge and corner sharing VO5 square pyramids. The as-prepared (NH4)0.5V2O5·mH2O nanobelts are up to several hundreds of micrometers long, 402–551 nm wide, and 235–305 nm thick. The thickness and width of the rings are respectively 454 nm and 1 μm. Triangles with three unequal sides having a thickness of 143 nm and a width of 1 μm were also formed. The crystalline orthorhombic phase of shcherbianite V2O5 was obtained on calcination of (NH4)0.5V2O5·mH2O at 350 °C for 2 h. The SEM image of this V2O5 product retains the parent morphology of the preheated compound. A possible reaction mechanism and the growth process involved in the formation of belts/rings/triangles and ovallike microstructures are discussed

NbO₂ a Highly Stable, Ultrafast Anode Material for Li- and Na-Ion Batteries

Anode materials with fast charging capabilities and stability are critical for realizing next-generation Li-ion batteries (LIBs) and Na-ion batteries (SIBs). The present work employs a simple synthetic strategy to obtain NbO2 and studies its applications as an anode for LIB and SIB. In the case of the LIB, it exhibited a specific capacity of 344 mAh g–1 at 100 mA g–1. It also demonstrated remarkable stability over 1000 cycles, with 92% capacity retention. Additionally, it showed a unique fast charging capability, which takes 30 s to reach a specific capacity of 83 mAh g–1. For the SIB, NbO2 exhibited a specific capacity of 244 mAh g–1 at 50 mA g–1 and showed 70% capacity retention after 500 cycles. Furthermore, detailed density functional theory reveals that various factors like bulk and surface charging processes, lower ion diffusion energy barriers, and superior electronic conductivity of NbO2 are responsible for the observed battery performances