The cobalt atom protection layers in-situ anchored titanium carbide with controllable interlayer spacing towards stable and fast lithium ions storage

Low-temperature molten-salt synthesis of Co3O4 nanoparticles grown on MXene can rapidly remove ornidazole via peroxymonosulfate activation

We further developed previous work on MXene materials prepared using molten salt methodology. We substituted single, with mixed salts, and reduced the melting point from >724 °C to <360 °C. Cobalt (Co) compounds were simultaneously etched and doped while the MXene material was created using various techniques in which Co compounds occur as Co3O4. The synthesized Co3O4/MXene compound was used as a peroxymonosulfate (PMS) activator that would generate free radicals to degrade antibiotic ornidazole (ONZ). Under optimal conditions, almost 100% of ONZ (30 mg/L) was degraded within 10 min. The Co3O4/MXene + PMS system efficiently degraded ONZ in natural water bodies, and had a broad pH adaptation range (4-11), and strong anion anti-interference. We investigated how the four active substances were generated using radical quenching and electron paramagnetic resonance (EPR) spectroscopy. We identified 12 ONZ intermediates by liquid chromatography-mass spectrometry and propose a plausible degradative mechanism.

Preparation and Evaluation of Co-Doped Fe7S8/C Composites for Lithium Storage

Fe₇S₈ has a high theoretical capacity (663 mAh g^-1) and can be prepared at a low cost, making it advantageous for production. However, Fe₇S₈ has two disadvantages as a lithium-ion battery anode material. The first is that the conductivity of Fe₇S₈ is not good. The second is that when the lithium ion is embedded, the volume expansion of the Fe₇S₈ electrode is serious. That is why Fe₇S₈ has not been used in real life yet. In this paper, Co-Fe₇S₈/C composites were prepared by doping Co into Fe₇S₈ through a one-pot simple hydrothermal method. In situ Co is doped into Fe₇S₈ to produce a more disordered microstructure to improve ion and electron transport performance, thereby reducing the activation barrier of the main material. The Co-Fe₇S₈/C electrode presents a high specific discharge capacity of 1586 mAh g^-1 and a Coulombic efficiency (CE) of 71.34% at an initial cycle at 0.1 A g^-1. After 1500 cycles, the specific discharge capacity remains at 436 mAh g^-1 (5 A g^-1). When the current density returns to 0.1 A g^-1, the capacity almost returns to the initial level, showing excellent rate performance.

Thermal Properties of MXenes and Relevant Applications

The properties and applications of MXenes (a family of layered transition metal carbides, nitrides, and carbonitrides) have aroused enormous research interests for a decade since the successful synthesis of few-layer transition metal carbides in 2011. Though MXenes, as the building blocks, have already been applied in various fields (such as wearable electronics) owing to the distinctive optical, mechanical and electrical properties, their thermal stability and intrinsic thermal properties were less thoroughly investigated compared to other characteristics in early reports. The pioneering theoretical prediction of the thermoelectric nature of MXenes was performed in 2013 while the first experiment-based report concerning the degradation behavior of the 2D structure at elevated temperatures in a controlled atmosphere was published in 2015, followed by numerous discoveries regarding the thermal properties of MXenes. Herein, after a brief description of the synthesis, this Review summarized the latest insights into the thermal stability and thermophysical properties of MXenes, and further associated these unique properties with relevant applications by multiple examples. Finally, current hurdles and challenges in this field were provided along with some advices on potential research directions in the future.