H₂O-Functionalized Zeolitic Zn(2-methylimidazole)₂ Framework (ZIF-8) for H₂ Storage

Abstract

It is generally recognized that H 2 O adsorption on a porous material would inhibit H 2 adsorption. However, this paper reports that stable H 2 O-functionalized Zeolitic Zn(2-methylimidazole) 2 Framework (ZIF-8), which was obtained by the simple water treatment of ZIF-8 at ambient temperature, can increase its H 2 adsorption heat from 5.2 to 10.1 kJ/mol. As a result, the reversible H 2 capacity at ambient temperature increased by 77%. This indicates that H 2 O-functionalization provides a novel approach to enhance ambient-temperature hydrogen storage in ZIF-8 and other metal-organic frameworks (MOFs).

Surface defection reduces cytotoxicity of Zn(2-methylimidazole)2 (ZIF-8) without compromising its drug delivery capacity

“…After treated in PBS, which was used as drug loading medium, the H-O-H bending groups in the range of 1620 to 1490 cm −1 appeared in the FT-IR spectra of all the defected ZIF-8 samples, indicating H 2 O was bound in these particles (Figure 1D). The bands of pristine ZIF-8 were consistent with our previous publication 23 . The FT-IR subtraction spectra of defected ZIF-8 were calculated by subtracting the IR spectrum of ZIF-8 from those of defected ZIF-8 samples.…”

“…Our previous density functional theory (DFT) calculation has proven that H 2 O molecules are bound to unsaturated Zn-sites of ZIF-8 through their oxygen atoms with binding energy of 80.5 kJ/moL, and the hydrogen atoms of H 2 O molecules are bound to the unsaturated N-sites of ZIF-8 with binding energy of 31.7 kJ/mol. The two energies are both much higher than the binding energy of physisorption (usually less than 10 kJ/moL), thus the unsaturated sites were preferentially re-saturated by H 2 O in PBS 23 .…”

“…This analysis was performed under 1 atm at room temperature. Crystal size was further calculated by the Scherrer equation 23 : $$\tau =\frac{K\lambda }{\beta \mathrm{italiccos}\theta }$$…”

“…As a representative ZIF, Zn(2-methylimidazole) 2 (ZIF-8) possesses a sodalite zeolite-type structure with large pores (11.6 Å in diameter), which are connected by apertures (3.4 Å in diameter). Our previous publications have revealed that bivalent cations result in a structural collapse of ZIF-8, and even water causes a gradual change in ZIF-8 crystal structure 22, 23 . Because of the large pore size, high surface area, as well as its degradability in aqueous environment, ZIF-8 has attracted much attention for delivering both hydrophilic and hydrophobic drugs, including 5-fluorouracil 24 , doxorubicin 25 , and several other drugs 26 .…”

Acetylene adsorption on defected MIL-53

“…C 2 H 2 adsorption on MIL‐53 with and without defects was measured by volumetric method at different temperatures (298 and 273 K) as follows: 0.2 g powder sample was loaded into a reactor and degassed under vacuum at 120 °C for 12 h. Then, C 2 H 2 was introduced into the reactor for adsorption at a selected temperature. The C 2 H 2 pressure change during adsorption was measured with an Accu‐Cal Plus 75514‐29B55 digital pressure gauge (3D Instruments, Anaheim, CA, USA) with a precision of 1 Torr, generating the adsorption isotherm of pressure versus the amount of adsorbed C 2 H 2 .…”