Direct accessibility of mixed-metal (iii/ii) acid sites through the rational synthesis of porous metal carboxylates

Abstract

The scalable and environmentally-friendly synthesis of mixed Fe(III)/M(II) (M = Ni, Co, Mg) polycarboxylate porous MOFs based on the Secondary Building Unit approach is reported. A combination of in situ infrared spectroscopy, (57)Fe Mössbauer spectrometry and adsorption microcalorimetry confirms the direct accessibility of the iron(III) and metal(II) sites under low temperature activation conditions.

Effect of Fe open metal site in metal‐organic frameworks on post‐combustion CO2 capture performance

“…Results of powder X-ray diffraction of the synthetic MIL-88A and MIL-127(Fe) samples (Fig. S1) show that XRPD patterns are in consistent with those reported in the literatures; 16,18,23 Nitrogen adsorption/desorption isotherm of MIL-127(Fe) shows type-I isotherm (Fig. S3), indicating that MIL-127(Fe) is a microporous material.…”

“…Parameters of the isotherm models examined for the dynamic adsorption of MOFs in our fixed-bed system are shown in Table 3. It should be noted that low adsorption capacity observed with our system is because adsorption process was carried out at low pressure, adsorption of large amount of CO 2 could be achieved at high operating pressure as reported by Wongsakulphasatch et al 23 This result reflects an outstanding capability of MOFs on CO 2 capture technology. This result implies that sorption of CO 2 molecules on the MOFs is held at localized sites, which plausibly be the attractive interaction at unsaturated Fe metal ion site as mentioned earlier.…”

“…Prediction results of maximum adsorption from Langmuir model shown in Table 3 reveals that these two MOFs could adsorb large amount of CO 2 molecules. It should be noted that low adsorption capacity observed with our system is because adsorption process was carried out at low pressure, adsorption of large amount of CO 2 could be achieved at high operating pressure as reported by Wongsakulphasatch et al 23 This result reflects an outstanding capability of MOFs on CO 2 capture technology. Also, it is observed from the predictive Langmuir model that equilibrium isotherm constant (K L ) decreases with increasing temperature, indicating…”

Exploring the Performance Improvement of the Oxygen Evolution Reaction in a Stable Bimetal–Organic Framework System

“…Herein, we designed and synthesized a series of MOFs based on Fe 2 M(μ 3 ‐O)(CH 3 COO) 6 (H 2 O) 3 (Fe 2 M, M=Fe, Co, Ni, Zn) clusters with the following considerations: 1) an iron atom in Fe 3 cluster can be replaced by a second metal with a similar radius that allows formation of Fe 2 M clusters, which is beneficial to realize the performance comparison of bimetallic electrocatalysts; 2) the preformed Fe 2 M clusters are soluble and can maintain their structure and composition, which guarantees the formation of desired bimetallic MOF‐based catalysts; and 3) the resulting bimetallic Fe 2 M‐MOFs feature enhanced chemical stability, satisfying the requirements of OER electrocatalysts. Accordingly, by bridging preformed Fe 2 M clusters with biphenyl‐3,4′,5‐tricarboxylic acid (BPTC) ligands, we prepared four isostructural Fe 2 M‐BPTC MOFs (Fe 3 ‐BPTC ( NNU‐21) , Fe 2 Co‐BPTC ( NNU‐22) , Fe 2 Ni‐BPTC ( NNU‐23 ) and Fe 2 Zn‐BPTC ( NNU‐24 )).…”

“Green” Synthesis of Metal‐Organic Frameworks

“…In contrast to this procedure, the originally reported synthesis conditions utilized iron perchlorate and the linker molecule under reflux in DMF . This MOF structure is especially of interest since comparable synthesis conditions under reflux allow also for the incorporation of mixed‐metal trimeric building units which are employed as preformed acetate building blocks . The synthesis times for compounds with MIL‐127 topology are rather long ranging from 24 to 72 hours.…”