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1.
Nanomaterials (Basel) ; 14(9)2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38727384

RESUMO

Motivated by the recent observation of Klein tunneling in 8-Pmmn borophene, we delve into the phenomenon in ß12 borophene by employing tight-binding approximation theory to establish a theoretical mode. The tight-binding model is a semi-empirical method for establishing the Hamiltonian based on atomic orbitals. A single cell of ß12 borophene contains five atoms and multiple central bonds, so it creates the complexity of the tight-binding model Hamiltonian of ß12 borophene. We investigate transmission across one potential barrier and two potential barriers by changing the width and height of barriers and the distance between two potential barriers. Regardless of the change in the barrier heights and widths, we find the interface to be perfectly transparent for normal incidence. For other angles of incidence, perfect transmission at certain angles can also be observed. Furthermore, perfect and all-angle transmission across a potential barrier takes place when the incident energy approaches the Dirac point. This is analogous to the "super", all-angle transmission reported for the dice lattice for Klein tunneling across a potential barrier. These findings highlight the significance of our theoretical model in understanding the complex dynamics of Klein tunneling in borophene structures.

2.
Environ Pollut ; 295: 118669, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34921941

RESUMO

Iron (III) co-precipitation with dissolved organic matter (DOM) is pervasive in many natural environments. However, the effects of DOM on the formation of Fe(III) hydroxysulfate (FHS) and its environmental implications are poorly understood. In this study, fulvic acid (FA) was used as a model DOM compound, and experiments were devised to investigate the effects of FA on the formation of FHS. In addition, the Pb(II) adsorption capabilities of FHSs biosynthesized under various FA dosages, including kinetics and sorption isotherm experiments, were conducted. These experiments showed that co-precipitation of FA promoted the formation of Fe-FA composites, FA-doped schwertmannite, and small particles of jarosite. Co-precipitates are more enriched in carboxyl (-COOH) functional groups due to their preferential binding with FHS. The adsorption kinetics, isotherms and mechanisms of Pb onto the biosynthesized FHSs were then comprehensively characterized and modeled. Though the specific surface area decreased with increasing FA loading, the introduction of FA into FHSs increased Pb(II) adsorption, with the highest concentration of FA addition improving the removal capacity of Pb(II) to 91.54%. Kinetics studies and intra-particle diffusion models indicated that the adsorption of Pb(II) onto the FHSs was correlated with the number of active sites, and two adsorption steps: surface adsorption and the diffusion of Pb(II) in channels inside the biosynthesized FHSs, are suggested. The adsorption mechanism was attributed to cation exchange between Pb(II) and -OH and -COOH functional groups, and the co-precipitated FA provided additional sites for Pb(II) adsorption by FHS.


Assuntos
Matéria Orgânica Dissolvida , Compostos Férricos , Adsorção , Benzopiranos , Cinética
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