Superlattice hydrogen storage alloys offer a compelling advantage with rapid hydriding rate and high storage capacity. However, its practical applications face challenges including complex structure, low dehydriding capacity, and cyclic instability. In this work, we successfully prepared La0.66Mg0.34Ni3.5–xCox superlattice hydrogen storage alloys with enhanced dehydriding capacity and stability by partially substituting Co for Ni. X-ray diffraction (XRD) refinements analysis reveals the presence of (La,Mg)3Ni9, (La,Mg)5Ni19, and LaNi5 phases within the alloy. Following Co substitution in the La0.66Mg0.34Ni3.4Co0.1 alloy, there is a significant increase in content of the (La, Mg)3Ni9 phase and a reduction in the hysteresis factor, resulting in an improved reversible hydrogen storage capacity from 1.45 wt% to 1.60 wt%. The dehydriding kinetics of the alloy is controlled by diffusion model with an activation energy of 8.40 kJ/mol. Furthermore, the dehydriding enthalpy value of the Co-substituted alloy decreases from 30.84 to 29.85 kJ/mol. Impressively, the cycling performance of the alloy after Co substitution exhibits excellent stability, with a capacity retention rate of 92.3% after 100 cycles. These findings provide valuable insights for the development of cost-effective hydrogen storage materials.
Neodymium-iron-boron (Nd-Fe-B) sludge is an important secondary resource of rare-earth elements (REEs). However, the state-of-the-art recycling method, i.e., HCl-preferential dissolution faces challenges such as slow leaching kinetics, excessive chemical consumption and wastewater generation. In this work, the in situ anodic leaching of Nd-Fe-B sludge was developed to selectively recover REEs with high efficiency. The leaching rates of the REEs are 2.4–9.0 times higher using the in situ anodic leaching at the current density from 10 to 40 mA/cm2 than using conventional chemical leaching under the maintained pH of 3.7. Mechanism studies reveal that the anode-generated H+ plays the key role during the in situ anodic leaching process that locally increases the H+ concentration at the interface of sludge particles, accelerating the leaching kinetics. By achieving a total leaching efficiency of Nd-Fe-B sludge close to 100% and the Fe deposition efficiency in the range of 70.9%–74.3%, selective leaching of REEs is successfully realized and thus largely reduces chemical consumption. Additionally, a two-step recycling route involving electrolysis-selective precipitation was proposed that enables a stable REEs recovery of 92.2% with recyclable electrolyte. This study provides a novel and environmentally-friendly strategy for the efficient recovery of REEs from secondary resources.
Herein we report novel photocatalysts ZnIn2S4–Ag–LaFeO3 with the core–shell structured materials prepared by hydrothermal method. In order to improve the efficiency of photocatalytic degradation of pollutants, LaFeO3 was prepared by hydrothermal followed by calcination, and further Ag nanoparticle (NP) was loaded onto the spherical structure of LaFeO3 by photolysis of silver nitrate, and finally the spherical ZnIn2S4–Ag–LaFeO3 photocatalyst was prepared by hydrothermal method again. The structure and properties of the as-prepared materials were characterized by X-ray photoelectron spectroscopy, ultraviolet–visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and fluorescence spectra. The results show that the synthesized composite photocatalysts display a significant improvement in photocatalytic efficiency relative to the single LaFeO3 and ZnIn2S4 and form a core–shell structure. Furthermore, the effect of the ratio of each component on the photocatalytic efficiency was investigated in detail, and it is discovered that at an Methylene Blue (MB) concentration of 0.219 mol/L, the degradation rate of MB is 95% at 120 min using 0.02 g of catalyst with an ideal ZnIn2S4:Ag:LaFeO3 ratio of 10:0.5:1. The possible mechanisms to improve the photocatalytic efficiency were explored.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：