Stabilized Li-Rich Layered Oxide Cathode by a Spontaneously Formed Yb and Oxygen-Vacancy Rich Layer on the Surface.

Li-rich layered oxides (LLOs) are among the most promising cathode materials with high theoretical specific capacity (>250 mAh g-1 ). However, capacity decay and voltage hysteresis due tostructural degradation during cycling impede the commercial application of LLOs. Surface engineering and element doping are two methods widely applied tomitigate the structural degradation. Here, it is found that trace amount lanthanide element Yb doping can spontaneously form a surficial Yb-rich layer with high density of oxygen vacancy on the LLO-0.3% Yb (Li1.2 Mn0.54 Co0.13-x Ybx Ni0.13 O2 where x = 0.003) cathodes, which mitigating lattice oxygen loss and the non-preferred layered-to-spinel-to-rock salt tri-phase transition. Meanwhile, there are also some Yb ions doped into the lattice of LLO, which enhance the binding energy with oxygen and stabilize the lattice in grain interior during cycling. The dual effects of Yb doping greatly mitigate the structure degradation during cycling, and facilitate fast diffusion of lithium ions. As a result, the LLO-0.3% Yb sample achieves significantly improved cycling stability, with a capacity retention of 84.69% after 100 cycles at 0.2 C and 84.3% after 200 cycles at 1 C. These finding shighlight the promising rare element doping strategy that can have both surface engineering and doping effects in preparing LLO cathodes with high stability.

Lanthanide-Doped ZnO Nanoparticles: Unraveling Their Role in Cytotoxicity, Antioxidant Capacity, and Nanotoxicology.

This study used a sonochemical synthesis method to prepare (La, Sm)-doped ZnO nanoparticles (NPs). The effect of incorporating these lanthanide elements on the structural, optical, and morphological properties of ZnO-NPs was analyzed. The cytotoxicity and the reactive oxygen species (ROS) generation capacity of ZnO-NPs were evaluated against breast (MCF7) and colon (HT29) cancer cell lines. Their antioxidant activity was analyzed using a DPPH assay, and their toxicity towards Artemia salina nauplii was also evaluated. The results revealed that treatment with NPs resulted in the death of 10.559-42.546% and 18.230-38.643% of MCF7 and HT29 cells, respectively. This effect was attributed to the ability of NPs to downregulate ROS formation within the two cell lines in a dose-dependent manner. In the DPPH assay, treatment with (La, Sm)-doped ZnO-NPs inhibited the generation of free radicals at IC50 values ranging from 3.898 to 126.948 µg/mL. Against A. salina nauplii, the synthesized NPs did not cause death nor induce morphological changes at the tested concentrations. A series of machine learning (ML) models were used to predict the biological performance of (La, Sm)-doped ZnO-NPs. Among the designed ML models, the gradient boosting model resulted in the greatest mean absolute error (MAE) (MAE 9.027, R2 = 0.86). The data generated in this work provide innovative insights into the influence of La and Sm on the structural arrangement and chemical features of ZnO-NPs, together with their cytotoxicity, antioxidant activity, and in vivo toxicity.

Rough and Porous Micropebbles of CeCu2Si2 for Energy Storage Applications.

Supercapacitors have attracted considerable attention due to their advantages, including being lightweight and having rapid charge-discharge, a good rate capability, and high cyclic stability. Electrodes are one of the most important factors influencing the performance of supercapacitors. Herein, a three-dimensional network of rough and porous micropebbles of CeCu2Si2 has been prepared using a one-step procedure and tested for the first time as a supercapacitor electrode. The synthesized material was extensively characterized in a three-electrode configuration using different electrochemical techniques, such as cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) tests, and electrochemical impedance spectroscopy (EIS). CeCu2Si2 shows rather high mass-capacitance values: 278 F/g at 1 A/g and 295 F/g at 10 mV/s. Moreover, the material exhibits remarkable long-term stability: 98% of the initial capacitance was retained after 20,000 cycles at 10 A/g and the Coulombic efficiency remains equal to 100% at the end of the cycles.

Vibrational and spectroscopic analysis of white light emitting Bi2SiO5 nanophosphor.

A series of Dy3+ ion activated Bi2SiO5 nanophosphors were synthesized by the hydrothermal and coprecipitation methods. Various structural and optical characterizations were made using X-ray diffraction, Scanning and Transmission electron microscopy, UV-Visible-Infrared absorption, Raman Spectroscopy, Photoluminescence, Time resolved luminescence techniques etc. Dy3+ ion doped samples yields characteristic bright yellow and blue emissions, on resonant excitation with 349nm and 386nm. The intensity ratio of the yellow/blue peaks was found to be function of Dy ion concentration and synthesis method. We have achieved white colour emission at 1.5mol% Dy concentration, CIE coordinate (0.36, 0.4) of which fall well within gamut of white light. The time-resolved fluorescence reveals decrease in radiative lifetime values with increasing Dy3+ ions concentration. A comparison between the samples synthesized by different methods, and Dy ion concentrations has been made and detail photo-physics involved is presented in the article.