CoNi Alloy Nanoparticles Embedded in Metal–Organic Framework‐Derived Carbon for the Highly Efficient Separation of Xenon and Krypton via a Charge‐Transfer Effect

Abstract

Separation of Xe and Kr is one of the greatest challenges in the gas industries owing to their close molecular structure and similar properties. Energy‐effective adsorption‐based separation using chemically stable carbon adsorbents is a promising technology. We propose a strategy for Xe/Kr separation using MOF‐derived metallic carbon adsorbents. M‐Gallate (M=Ni, Co) were used as precursors to fabricate CoNi alloy nanoparticles embedded carbon adsorbents by one‐step auto‐reduction pyrolysis. The optimal NiCo@C‐700 exhibits record‐high IAST selectivity (24.1) and Henry's selectivity (20.1) of Xe/Kr among reported carbon adsorbents. DFT calculations, local density of states calculation, charge density difference, and Bader charge analysis reveal the great affinity with Xe benefits from the presence of Ni or CoNi nanoparticles as a result of more charge transfer from Xe than Kr to metal, thus providing higher binding energy. Breakthrough experiments further verify NiCo@C‐700 a promising candidate for Xe/Kr separation.

Deep Desulfurization with Record SO2 Adsorption on the Metal–Organic Frameworks

“…Over the past decades, energy-efficient adsorption separation that has showed great potential in desulfurization encourages the development of task-specific adsorbents. − Traditional adsorbents like porous carbons − and zeolites − have been extensively investigated in SO 2 capture and removal. Nevertheless, porous carbons feature the wide pore size distribution and lack strong binding sites, thus showing low selectivity of SO 2 .…”

High-efficiency radon adsorption by nickel nanoparticles supported on activated carbon

“…25,42 DFT calculations showed that Ni atoms strongly adsorb onto xenon atoms. 43 To further investigate the effect of the calcination temperature of Ni/AC on the valence state of nickel metal, XPS was adopted to analyze the surface valence of nickel. The chemical states of nickel in Ni/AC are shown in Fig.…”

“…24 Density functional theory calculations have revealed that charge transfer from Xe to Ni or CoNi nanoparticles could result in a higher binding energy and thus the excellent affinity toward Xe. 43 The polarizability of the noble gases increases with the increasing atomic number in the periodic table. Since there seems to be a correlation with the size of the noble atoms, this phenomenon suggests that the efficiency should be even higher for radon.…”

“…Moreover, the relevant literature has confirmed that Ni has a polarizing effect on noble gases Kr and Xe, and the polarization effect is stronger on Xe than on Kr. 43 The atomic radius of Kr, Xe and Rn are 0.364 nm, 0.410 nm, and 0.417 nm, respectively. 11 Because krypton, xenon and radon belong to the same group of elements on the periodic table, the outermost electrons are arranged in the same way.…”

“…For example, the interaction between Ni-MOF-74 and Xe can be enhanced by its open metal sites;37 the Ag nanoparticles in Ag@Ni-MOF-74 channels can also induce Xe polarization and enhance the interaction with Xe 24. Density functional theory calculations have revealed that charge transfer from Xe to Ni or CoNi nanoparticles could result in a higher binding energy and thus the excellent affinity toward Xe 43. The polarizability of the noble gases increases with the increasing atomic number in the periodic table.…”