A facile fabrication of sepiolite mineral nanofibers with excellent adsorption performance for Cd2+ ions

Recent Progress on Natural Clay Minerals for Lithium-Sulfur Batteries

Li-S batteries with high energy density have the potential to become a viable alternative to Li-ion batteries. However, Li-S batteries still face several challenges, including the shuttle effect, low conversion kinetics, and Li dendrite growth. Natural clay minerals with porous structures, abundant Lewis-acid sites, high mechanical modulus, and versatile structural regulation show great potential for improving the performance of Li-S batteries. However, so far, relevant reviews focusing on the applications of natural clay minerals in Li-S batteries are still missing. To fill the gap, this review first presents an overview of the crystal structures of several natural clay minerals, including 1D (halloysites, attapulgites, and sepiolite), 2D (montmorillonite and vermiculite), and 3D (diatomite) structures, providing a theoretical basis for the application of natural clay minerals in Li-S batteries. Subsequently, research advancements in the natural clay-based energy materials in Li-S batteries have been comprehensively reviewed. Finally, the perspectives concerning the development of natural clay minerals and their applications in Li-S batteries are provided. We hope this review can provide timely and comprehensive information on the correlation between the structure and function of natural clay minerals in Li-S batteries and offer guidance for material selection and structure optimization of natural clay-based energy materials.

Electron-Scale Insights into the Single and Coadsorption Cd(II) Behaviors of a Metal-Nonmetal-Modified Titanium Dioxide

Metal (Fe) and nonmetal (P) were used to modify TiO2, and then, several functional groups such as P-O, P=O, Fe-O, and -OH were introduced on its surface to enhance the adsorption capacity for Cd(II), which could reach 121 mg/g. According to the experimental analysis of adsorption performance, chemical adsorption dominates the adsorption process, and the adsorption capacity increases with increasing temperature within a certain range. The results of competitive adsorption experiments showed that both Pb(II) and Cu(II) affect the adsorption of Cd(II) and that the adsorption order of P-Fe-TiO2 for heavy metal ions is $\text{Pb}\left(\text{II}\right)>\text{Cd}\left(\text{II}\right)>\text{Cu}\left(\text{II}\right)$ . We further investigated the adsorption mechanism of P-Fe-TiO2 for Cd(II) and the reasons for the difference in competitive adsorption and used DFT calculations to confirm the experimental results. In the analysis of binding energy and frontier molecular orbitals (FMOs), we confirmed that charge transfer occurred during the adsorption process, so chemical reactions occurred. The binding energy of P-Fe-TiO2 and Pb(II) is the largest. The results of the competitive adsorption experiment also confirmed that the adsorbent has the greatest effect on Pb. Mulliken analysis was used to identify the best binding site on the adsorbent. The results of electrostatic potential, total potential, and differential charge analysis further prove the conclusions described above.