Core–shell ZIF-8@ZIF-67- and ZIF-67@ZIF-8-based zeolitic imidazolate frameworks (ZIFs) were synthesized solvothermally using a seed-mediated methodology. Transmission electron microscopy–energy-dispersive X-ray spectrometry, line scan, elemental mapping, X-ray photoelectron spectroscopy, and inductively coupled plasma-atomic emission spectroscopy analyses were performed to confirm the formation of a core–shell structure with the controlled Co/Zn elemental composition of ∼0.50 for both the core–shell ZIFs. The synthesized core–shell ZIF-8@ZIF-67 and ZIF-67@ZIF-8 frameworks conferred enhanced H 2 (2.03 and 1.69 wt %) storage properties at 77 K and 1 bar, which are ca. 41 and 18%, respectively, higher than that of the parent ZIF-8. Notably, the distinctly remarkable H 2 storage properties shown by both the core–shell ZIFs over the bimetallic Co/Zn-ZIF and the physical mixture of ZIF-8 and ZIF-67 clearly evidenced their unique structural properties (confinement of porosity) and elemental heterogeneity due to the core–shell morphology of the outperforming core–shell ZIFs. Moreover, H 2 adsorption isotherm data of these frameworks are best fitted with the Langmuir model ( R 2 ≥ 0.9999). Along with the remarkably enhanced H 2 storage capacities, the core–shell ZIFs also displayed an improved CO 2 capture behavior. Hence, we demonstrated here that the controlled structural features endorsed by the rationally designed porous materials may find high potential in H 2 storage applications.

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Metal-organic frameworks (MOFs) show promising characteristics for hydrogen storagea pplication.I nt his direction, modification of under-utilized large pore cavities of MOFs has been extensively explored as ap romising strategy to further enhancet he hydrogen storage properties of MOFs. Here, we describedasimple methodology to enhance the hydrogen uptake properties of RHA incorporated MIL-101 (RHA-MIL-101,w here RHA is rice husk ash-a waste material) by controlled doping of Li + ions. The hydrogen gas uptake of Li-doped RHA-MIL-101 is significantly higher (up to 72 %) compared to the undoped RHA-MIL-101, where the content of Li + ions dopingg reatly influenced the hydrogen uptake properties. We attributed the observed enhancement in the hydrogen gas uptake of Li-dopedR HA-MIL-101 to the favorableL i + ion-to-H 2 interactions and the cooperative effect of silanol bonds of silica-rich rice-huska sh incorporated in MIL-101.[b] Dr.

A sustainable methodology was explored to synthesize carbon−MIL-101 hybrid composites by advantageously inducing in situ hydrothermal carbonization (HTC) of glucose during the synthesis of MIL-101. Carbon−MIL-101 hybrid composites with varying carbon contents were synthesized by tuning the content of glucose. The HTC of glucose and incorporation of carbon in MIL-101 were confirmed by probing 13 C nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman investigations. The microporosity of composites can be fine-tuned by optimizing the carbon loading. Consequently, the carbon−MIL-101 hybrid composites with an optimized pore size and high pore volume and surface area conferred enhanced H 2 uptake properties (by ca. 11% compared to MIL-101) at 77 K and 1 bar. The noteworthy enhancement in H 2 uptake for the synthesized carbon−MIL-101 hybrid composites endorsed the potential of the studied methodology to design hybrid metal−organic framework composites with tuned porosity for H 2 storage application.

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