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Title: Non-Precious Metal Catalysts Prepared By Zeolitic Imidazolate Frameworks: The Ligand Influence to Morphology and Performance

Abstract

A new, “one-pot” synthesis to produce highly active non-PGM electrocatalysts for PEM fuel cells was previously developed by pyrolyzing Fe doped zeolitic imidazolate framework (ZIF) materials prepared by solid-state interaction. Excellent catalytic oxygen reduction reaction (ORR) activities were found through rotating ring-disk electrode (RRDE) and single fuel cell tests. In this study, we compared the ORR activities and structural properties of two catalysts derived from ZIFs containing imidazole and methyl imidazole ligands, respectively. Our results indicate that alkyl group substitution in the imidazolate ligand has a profound effect on the final catalyst performance.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE) - Office of Fuel Cell Technologies (FCTO); USDOE Office of Science (SC)
OSTI Identifier:
1332999
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Fuel Cells; Journal Volume: 16; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
Catalyst; Metal Organic Frameworks; fuel cells

Citation Formats

Barkholtz, H. M., Chong, L., Kaiser, Z. B., and Liu, D. -J. Non-Precious Metal Catalysts Prepared By Zeolitic Imidazolate Frameworks: The Ligand Influence to Morphology and Performance. United States: N. p., 2016. Web. doi:10.1002/fuce.201500164.
Barkholtz, H. M., Chong, L., Kaiser, Z. B., & Liu, D. -J. Non-Precious Metal Catalysts Prepared By Zeolitic Imidazolate Frameworks: The Ligand Influence to Morphology and Performance. United States. doi:10.1002/fuce.201500164.
Barkholtz, H. M., Chong, L., Kaiser, Z. B., and Liu, D. -J. 2016. "Non-Precious Metal Catalysts Prepared By Zeolitic Imidazolate Frameworks: The Ligand Influence to Morphology and Performance". United States. doi:10.1002/fuce.201500164.
@article{osti_1332999,
title = {Non-Precious Metal Catalysts Prepared By Zeolitic Imidazolate Frameworks: The Ligand Influence to Morphology and Performance},
author = {Barkholtz, H. M. and Chong, L. and Kaiser, Z. B. and Liu, D. -J},
abstractNote = {A new, “one-pot” synthesis to produce highly active non-PGM electrocatalysts for PEM fuel cells was previously developed by pyrolyzing Fe doped zeolitic imidazolate framework (ZIF) materials prepared by solid-state interaction. Excellent catalytic oxygen reduction reaction (ORR) activities were found through rotating ring-disk electrode (RRDE) and single fuel cell tests. In this study, we compared the ORR activities and structural properties of two catalysts derived from ZIFs containing imidazole and methyl imidazole ligands, respectively. Our results indicate that alkyl group substitution in the imidazolate ligand has a profound effect on the final catalyst performance.},
doi = {10.1002/fuce.201500164},
journal = {Fuel Cells},
number = 4,
volume = 16,
place = {United States},
year = 2016,
month = 8
}
  • A new tetradentate imidazolate ligand 1,1',1'',1'''-(2,2',4,4',6,6'-hexamethylbiphenyl-3,3',5,5'-tetrayl) tetrakis(methylene)(1H-imidazole) (L) and four Ag(I)/Cu(I) coordination polymers, namely [(MCN){sub 3}L]{sub n} (1: M=Ag; 2: M=Cu), and [(MSCN){sub 2}L]{sub n} (3: M=Ag; 4: M=Cu) are described. All four new coordination polymers were fully characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. Compound 1 features a 3D supramolecular framework constructed by 1D chains through inter-chain Ag-N(CN) and inter-layer Ag-N(L) weak interactions with an uninodal 6{sup 6} topology. Complex 2 presents a 3D framework characterized by a tetranodal (3,4)-connected (3.4.5.10{sup 2}.11)(3.4.5.6.7.9)(3.6.7)(6.10{sup 2}) topology. Complexes 3 and 4 are isostructural, and both have a 3D networkmore » of trinodal 4-connected (4.8{sup 5}){sub 2}(4{sup 2}.8{sup 2}.10{sup 2})(4{sup 2}.8{sup 4}){sub 2} topology. The luminescent properties for these compounds in the solid state as well as the possible ferroelectric behavior of 1 are discussed. - Graphical abstract: Four coordination polymers built upon Ag(I)/Cu(I) pseudohalides and a imidazolate ligand have been solvothermally synthesized. The luminescent properties for these compounds and the possible ferroelectric behavior of 1 are discussed.« less
  • Nano sized zeolitic imidazolate frameworks [nZIF-8] with excellent chemical and thermal stability has been synthesized at room temperature by simple mixing of 2-methylimidazole and zinc nitrate hexahydrate in methanol/ 1% high molecular weight poly(diallyldimethylammonium chloride) solution for 24 hrs
  • When all cages are assumed to be accessible, popular force fields such as universal force field (UFF) and DREIDING dramatically overpredicted gas adsorption capacity in two widely studied zeolitic-imidazolate frameworks (ZIFs), ZIF-68 and -69. Instead of adjusting the force-field parameters to match the experiments, herein we show that when the pore topology and accessibility are correctly taken into account, simulations with the standard force fields agree very well with the experiments. Careful inspection shows that ZIF-68 and -69 have two one-dimensional channels, which are not interaccessible to gases. The small channel consists of alternating small (HPR) and medium (GME) cages,more » while the large channel comprises the large (KNO) cages. Our analysis indicates that the small channel is not accessible to gases such as CO{sub 2}. So when the cages in the small channel are intentionally blocked in our simulation, the predicted adsorption capacities of CO{sub 2}, CH{sub 4} and N{sub 2} at room temperature from standard force-field parameters for the framework show excellent agreement with the experimental results. In the case of H{sub 2}, all cages are accessible, so simulation results without cage-blocking show excellent agreement with experiment. Due to the promising potential of ZIFs in gas storage and separation, our work here shows that pore topology and accessibility should be carefully examined to understand how gases adsorb in ZIFs.« less
  • Zeolites are one of humanity’s most important synthetic products. These aluminosilicate-based materials represent a large segment of the global economy. Indeed, the value of zeolites used in petroleum refining as catalysts and in detergents as water softeners is estimated at $350 billion per year. A major current goal in zeolite chemistry is to create a structure in which metal ions and functionalizable organic units make up an integral part of the framework. Such a structure, by virtue of the flexibility with which metal ions and organic moieties can be varied, is viewed as a key to further improving zeolite propertiesmore » and accessing new applications. Recently, it was recognized that the Si-O-Si preferred angle in zeolites (145°) is coincident with that of the bridging angle in the M-Im-M fragment (where M is Zn or Co and Im is imidazolate), and therefore it should be possible to make new zeolitic imidazolate frameworks (ZIFs) with topologies based on those of tetrahedral zeolites. This idea was successful and proved to be quite fruitful; within the last 5 years over 90 new ZIF structures have been reported. The recent application of high-throughput synthesis and characterization of ZIFs has expanded this structure space significantly: it is now possible to make ZIFs with topologies previously unknown in zeolites, in addition to mimicking known structures. In this Account, we describe the general preparation of crystalline ZIFs, discussing the methods that have been developed to create and analyze the variety of materials afforded. We include a comprehensive list of all known ZIFs, including structure, topology, and pore metrics. We also examine how complexity might be introduced into new structures, highlighting how link-link interactions might be exploited to effect particular cage sizes, create polarity variations between pores, or adjust framework robustness, for example. The chemical and thermal stability of ZIFs permit many applications, such as the capture of CO 2 and its selective separation from industrially relevant gas mixtures. Currently, ZIFs are the best porous materials for the selective capture of CO 2; furthermore, they show exceptionally high capacity for CO 2 among adsorbents operating by physisorption. The stability of ZIFs has also enabled organic transformations to be carried out on the crystals, yielding covalently functionalized isoreticular structures wherein the topology, crystallinity, and porosity of the ZIF structure are maintained throughout the reaction process. Finally, these reactions, being carried out on macroscopic crystals that behave as single molecules, have enabled the realization of the chemist’s dream of using “crystals as molecules”, opening the way for the application of the extensive library of organic reactions to the functionalization of useful extended porous structures.« less