Ag Nanoparticles decorated few-layer Nb2CT nanosheets architectures with superior lithium/sodium-ion storage

WS2 nanosheets vertically grown on Ti3C2 as superior anodes for lithium-ion batteries

Tungsten disulfide (WS2) is considered as a promising anode material for high-performance lithium-ion batteries (LIBs) result from its inherent characteristics such as high theoretical capacity, large interlayer spacing and weak interlayer Van der Waals force. Nevertheless, WS2 has the drawbacks of easy agglomeration, severe volume expansion and high Li+ migration barrier, which lead to rapid capacity degradation and imperfect rate ability. In this work, a novel two-dimensional (2D) hierarchical composite (Ti3C2/WS2) consisting of WS2 nanosheets vertically grown on titanium carbide (Ti3C2) nanosheets is prepared. Thanks to this distinctive hierarchical structure and synergy between WS2 and Ti3C2, the Ti3C2/WS2 composite demonstrates exceptional electrochemical performance in LIBs. In addition, we investigate the effect of the mass proportion of WS2 in Ti3C2/WS2 composite on the electrochemical performance, and find that the optimal mass ratio of WS2 is 60%. As expected, the optimal electrode exhibits a high specific capacity (650 mAh/g at 0.1 A/g after 100 cycles) and ultra-long cycle stability (400 mAh/g at 1.0 A/g after 5000 cycles).

Ultra-Efficient Synthesis of Nb4 C3 Tx MXene via H2 O-Assisted Supercritical Etching for Li-Ion Battery

Nb4 C3 Tx MXene has shown extraordinary promise for various applications owing to its unique physicochemical properties. However, it can only be synthesized by the traditional HF-based etching method, which uses large amounts of hazardous HF and requires a long etching time (> 96 h), thus limiting its practical application. Here, an ultra-efficient and environmental-friendly H2 O-assisted supercritical etching method is proposed for the preparation of Nb4 C3 Tx MXene. Benefiting from the synergetic effect between supercritical CO2 (SPC-CO2 ) and subcritical H2 O （SBC-H2 O）, the etching time for Nb4 C3 Tx MXene can be dramatically shortened to 1 h. The as-synthesized Nb4 C3 Tx MXene possesses uniform accordion-like morphology and large interlayer spacing. When used as anode for Li-ion battery, the Nb4 C3 Tx MXene delivers a high reversible specific capacity of 430 mAh g-1 at 0.1 A g-1 , which is among the highest values achieved in pure-MXene-based anodes. The superior lithium storage performance of the Nb4 C3 Tx MXene can be ascribed to its high conductivity, fast Li+ diffusion kinetics and good structural stability.

Endogenous Nb2CTx/Nb2O5 Schottky heterostructures for superior lithium-ion storage

Schottky heterostructures have significant advantages for exciting charge transfer kinetics at material interfaces. In this work, endogenous Nb2CTx/Nb2O5 Schottky heterostructures with a large active surface area were constructed using an in-situ architectural strategy. The semiconductor Nb2O5 has a low work function, and during the construction of Nb2CTx/Nb2O5 Schottky heterostructures, there was an interfacial electron transfer, which resulted in a built-in electric field. The electrochemical reaction kinetics of Nb2CTx/Nb2O5 Schottky heterostructures were enhanced due to the rapid transfer of charge driven by the electric field. The Nb2CTx/Nb2O5 Schottky heterostructures have a large active surface area, which contributes to excellent electrolyte diffusion kinetics. Therefore, Nb2CTx/Nb2O5 Schottky heterostructures have excellent lithium-ion storage capacity with 575 mAh/g after 200 cycles at 0.10 A/g, and 290 mAh/g after 1000 cycles at 2.00 A/g, without capacity fading. Furthermore, in-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy analyses reveal the mechanisms for structure evolution and lithium-ion storage optimization of Nb2CTx/Nb2O5 Schottky heterostructures during the electrochemical reaction. The construction of Schottky heterostructures with excited charge transport kinetics provides a novel idea for optimizing the lithium-ion storage activity of MXenes materials.

Green synthesized Ag decorated CeO2 nanoparticles: Efficient photocatalysts and potential antibacterial agents

Implication of natural resources for manufacturing of nanoparticles is sustainable, economical and contaminant free approach towards ecological and medical applications. Herein, CeO₂ and Ag/CeO₂ nanoparticles are green synthesized from Morinda tinctoria plant extract. The phase structure, surface morphology, optical identity, Ce(III) and Ce(IV) valency of the synthesized CeO₂ and Ag/CeO₂ nanoparticles are explored. The X-ray diffraction analysis indicated the formation of cubic phase CeO₂ and cubic silver decorated CeO₂ nanoparticles. Fourier transform infrared (FTIR) spectroscopy revealed the metal decoration of CeO₂ nanoparticles, metal-oxygen stretching, indicating the plant molecules reduction and stabilization. UV-visible spectroscopy shown the decreased band gap owing to silver modification. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs displayed spherical morphology of the nanoparticles. Elemental composition and sample purity is assessed by energy dispersive spectroscopy (EDS). Double oxidation of Ce, double splitting energy of Ag and lattice oxygen are observed from X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of Ag/CeO₂ exposed the enhanced photocatalytic activity up to 94% where CeO₂ nanoparticles gave 60% degradation of bromophenol blue (BB). The plasmonic decoration of silver on the ceria surface induced the charge separations and free radical reactions. Moreover, Ag/CeO₂ nanoparticles are seen as superior antibacterial agents than CeO₂ towards both E.coli and S.aureus. Hence, the silver decorated metal oxide photocatalyst successfully degraded the BB dye and inactivated the bacterial strains. This report established a future research in green synthesis of multipurpose metal nanoparticles.

V2CTX catalyzes polysulfide conversion to enhance the redox kinetics of Li-S batteries

Lithium-sulfur (Li-S) batteries have the potential to become the future energy storage system, yet they are plagued by sluggish redox kinetics. Therefore, enhancing the redox kinetics of polysulfides is key for the development of high-energy density and long-life Li-S batteries. Herein, a Ketjen Black (KB)/V₂CT_X modified separator (KB/V₂CT_X-PP) based on the catalytic effect in continuous solid-to-liquid-to-solid reactions is proposed to accelerate the conversion of sulfur species during the charge/discharge process in which the V₂CT_X can enhance the redox kinetics and inhibit polysulfide shuttling. The cells assembled with KB/V₂CT_X-PP achieve a gratifying first discharge capacity of 1236.1 mA h g^-1 at 0.2C and the average capacity decay per cycle reaches 0.049% within 1000 cycles at 1C. The work provides an efficient idea to accelerate redox conversion and suppress shuttle effects by designing a multifunctional catalytic separator.