Adsorption studies in flexible metal-organic frameworks are challenging and time-consuming. It is mainly because the mechanism of adsorption, defined by structural framework properties, is constantly modified during the process, as the framework transformation depends on the adsorption uptake. We propose here a new approach to investigate adsorption in such complex systems, in which the simulations of adsorption in a deforming framework are replaced by the analysis of adsorption in intermediate rigid structures. As a proof of concept we analyze carbon dioxide, hexane, and methane adsorption in MIL-53. 19 intermediate structures were generated using geometrical interpolation between the open and the closed MOF forms and optimized with quantum DFT calculations. The grand canonical Monte Carlo method was applied to calculate adsorption isotherms in all intermediate structures. The comparison with experimental results enabled the identification of the intermediate adsorption states. The analysis of the microscopic configurations of the adsorbed molecules in these structures allowed us to propose a new mechanism of adsorbate evolution over the entire process.
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http://dx.doi.org/10.1039/c8cp06817h | DOI Listing |
ACS Appl Mater Interfaces
January 2025
School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China.
Defective MOFs have been identified as promising candidates for efficient membrane-based separation applications. However, the utilization of defective MOFs in membrane gas separation is still in its infancy due primarily to the inefficient molecular differentiation induced by structural defects. Herein, we report a strategic combination of ionic liquid (IL) and defective UiO-66-NH MOF to ameliorate the CO/N selectivity within the highly permeable PIM-1 polymer.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
State Key Laboratory for Chemo/Biosensing and Chemometrics, Advanced Catalytic Engineering Research Center of the Ministry of Education and College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
The cobalt-nitrogen-carbon (Co─N─C) single-atom catalysts (SACs) are promising alternatives to precious metals for catalyzing the hydrogen evolution reaction (HER) and their activity is highly dependent on the coordination environments of the metal centers. Herein, a NaHCO etching strategy is developed to introduce abundant in-plane pores within the carbon substrates that further enable the construction of low-coordinated and asymmetric Co─N sites with nearby vacancy defects in a Co─N─C catalyst. This catalyst exhibits a high HER activity with an overpotential (η) of merely 78 mV to deliver a current density of 10 mA cm, a Tafel slope of 45.
View Article and Find Full Text PDFChemistry
January 2025
China University of Geosciences, Faculty of Materials Science and Chemistry, CHINA.
Pd cocatalysts show great potential for the photocatalytic production of H2O2. However, the catalytic efficiency of Pd cocatalyst is limited due to the strong adsorption of O2, which promotes O-O bond cleavage and thus reduces selectivity for the two-electron O2 reduction reaction. Considering that adjusting the electron density of Pd can predominately optimize Pd-Oads bond strength, in this work, electron-rich Pd sites are constructed by introducing Bi2Se3 middle layer between Pd cocatalysts and (010) facet of BiVO4 using an in-situ selenization strategy.
View Article and Find Full Text PDFEnviron Monit Assess
January 2025
Department of Environmental Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq.
J Mol Model
January 2025
College of Electronics and Information, Xi'an Polytechnic University, Xian, People's Republic of China.
Context: The two-dimensional graphene/MoTe heterostructure holds extensive potential applications in optoelectronic devices, sensors, and catalysts. To expand its optical applications, this study systematically investigates the adsorption stability of metal atoms (Au, Pt, Pd, and Fe) on the graphene/MoTe and their influence on its optoelectronic properties employing first-principles methods. The findings indicate that after the adsorption of Au and Pd, the structure retains its direct bandgap properties, while the adsorption of Pt and Fe exhibits indirect bandgap characteristics.
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