Co-reporter:Yaozu Liao, Zhonghua Cheng, Weiwei Zuo, Arne Thomas, and Charl F. J. Faul
ACS Applied Materials & Interfaces November 8, 2017 Volume 9(Issue 44) pp:38390-38390
Publication Date(Web):October 18, 2017
DOI:10.1021/acsami.7b09553
Nitrogen-rich conjugated microporous polymers (NCMPs) have attracted great attention in recent years owing to their polarity, basicity, and ability to coordinate metal ions. Herein, three NCMPs, structurally close to polyaniline, were facilely synthesized via chemical oxidative polymerization between multiconnected aniline precursors. The NCMPs with high N content (11.84 wt %), intrinsic ultramicroporosity (<1 nm), and moderate surface area (485 m2 g–1) show wide-ranging adsorption functionality, e.g., CO2 uptake (11 wt %) and CO2-selectivity over N2 (360, 1 bar), 1.0 wt % H2 storage, as well as 215 wt % iodine vapor uptake at ambient pressure. Moreover, these NCMPs act as support for palladium catalysts and can maintain >94% activity in Suzuki–Miyaura coupling reactions after six continuous runs.Keywords: catalysis; conjugated microporous polymers; gas storage; polyaniline networks; synthesis;
Co-reporter:Matthias Trunk, Johannes F. Teichert, and Arne Thomas
Journal of the American Chemical Society March 15, 2017 Volume 139(Issue 10) pp:3615-3615
Publication Date(Web):March 1, 2017
DOI:10.1021/jacs.6b13147
Porous polymer networks based on sterically encumbered triphenylphosphine motifs, mimicking the basic sites employed in frustrated Lewis pair (FLP) chemistry, were synthesized via Yamamoto polymerization and their interactions with the strong Lewis acid B(C6F5)3 probed. The combinations yield semi-immobilized FLPs, which are able to cleave dihydrogen heterolytically at ambient temperature and low hydrogen pressure.
Co-reporter:Robin J. White, Anna Fischer, Caren Goebel, and Arne Thomas
Journal of the American Chemical Society February 19, 2014 Volume 136(Issue 7) pp:2715-2718
Publication Date(Web):January 7, 2014
DOI:10.1021/ja411586h
A generalized synthesis of high-quality, mesoporous zeolite (e.g., MFI-type) nanocrystals is presented, based on a biomass-derived, monolithic N-doped carbonaceous template. As an example, ZSM-5 single crystals with desirable large-diameter (12–16 nm) intracrystalline mesopores are synthesized. The platform provides scope to optimize template dimensions and chemistry for the synthesis of a range of micro-/mesoporous crystalline zeolites in a cost-effective and highly flexible manner.
Co-reporter:Daniel Becker;Nora Konnertz;Martin Böhning;Johannes Schmidt;Arne Thomas
Chemistry of Materials December 13, 2016 Volume 28(Issue 23) pp:8523-8529
Publication Date(Web):October 28, 2016
DOI:10.1021/acs.chemmater.6b02619
The interest in (micro)porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV–vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each.
Co-reporter:Shuang Li;Chong Cheng;Hai-Wei Liang;Xinliang Feng;Arne Thomas
Advanced Materials 2017 Volume 29(Issue 28) pp:
Publication Date(Web):2017/07/01
DOI:10.1002/adma.201700707
2D porous carbon nanomaterials have attracted tremendous attention in different disciplines especially for electrochemical catalysis. The significant advantage of such 2D materials is that nearly all their surfaces are exposed to the electrolyte and can take part in the electrochemical reaction. Here, a versatile active-salt-templating strategy to efficiently synthesize 2D porous carbon nanosheets from layered organic–inorganic hybrids is presented. The resulting heteroatom-doped carbon nanosheets (NFe/CNs) exhibit exceptional performance for the oxygen-reduction reaction and in Zn–air battery electrodes. The activity of the best catalyst within a series of NFe/CNs exceeds the performance of conventional carbon-supported Pt catalysts in terms of onset potential (0.930 vs 0.915 V of Pt/C), half-wave potential (0.859 vs 0.816 V of Pt/C), long-time stability, and methanol tolerance. Also, when applied as a cathode catalyst in a zinc–air battery the NFe/CNs presented here outperform commercial Pt/C catalysts.
Co-reporter:Ali Yassin;Matthias Trunk;Frank Czerny;Pierre Fayon;Abbie Trewin;Johannes Schmidt;Arne Thomas
Advanced Functional Materials 2017 Volume 27(Issue 26) pp:
Publication Date(Web):2017/07/01
DOI:10.1002/adfm.201700233
Nitrogen-rich solid absorbents, which have been immensely tested for carbon dioxide capture, seem until this date to be without decisive molecular engineering or design rules. Here, a family of cyanovinylene-based microporous polymers synthesized under metal-catalyzed conditions is reported as a promising candidate for advanced carbon capture materials. These networks reveal that isosteric heats of CO2 adsorption are directly proportional to the amount of their functional group. Motivated by this finding, polymers produced under base-catalyzed conditions with tailored quantities of cyanovinyl content confirm the systematical tuning of their sorption enthalpies to reach 40 kJ mol−1. This value is among the highest reported to date in carbonaceous networks undergoing physisorption. A six-point-plot reveals that the structure–thermodynamic-property relationship is linearly proportional and can thus be perfectly fitted to tailor-made values prior to experimental measurements. Dynamic simulations show a bowl-shaped region within which CO2 is able to sit and interact with its conjugated surrounding, while theoretical calculations confirm the increase of binding sites with the increase of PhCC(CN)Ph functionality in a network. This concept presents a distinct method for the future design of carbon dioxide capturing materials.
Co-reporter:Nicolas Chaoui;Matthias Trunk;Robert Dawson;Johannes Schmidt;Arne Thomas
Chemical Society Reviews 2017 vol. 46(Issue 11) pp:3302-3321
Publication Date(Web):2017/06/06
DOI:10.1039/C7CS00071E
Microporous polymers are covalently bound, entirely organic materials which possess very high surface areas. These materials have been intensively studied within recent years and various interesting properties and possible applications have been discovered and described. This review article starts with the question, what makes microporous polymers special and are there certain features which differentiate them from other microporous materials? Indeed, there are some special structural and functional features found in microporous polymers which make them really unique and merit further exploration. We focus here on microporous polymers which are solution-processable, can be produced as thin films on electrodes by oxidative polymerizations, are π-conjugated organic semiconductors, or which provide the possibility to introduce and exploit distinct functional groups in an otherwise non-functional highly porous environment. Emerging applications for these microporous polymers which make explicit use of these unique features are further presented.
Co-reporter:Yaozu Liao;Zhonghua Cheng;Matthias Trunk;Arne Thomas
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 46) pp:7240-7247
Publication Date(Web):2017/11/28
DOI:10.1039/C7PY01439B
We report a conjugated microporous polycarbazole network and its pyridine-, bipyridine-, and cyano-functionalized networks exhibiting large surface area (1126 m2 g−1), isosteric heat of CO2 adsorption (∼32 kJ mol−1), and CO2-uptake capacity (14 wt% at 1 bar and 273 K). IAST calculations using single-component-isotherms reveal that the functionalized polycarbazole networks have a very high CO2 selectivity over N2 (164) under ambient conditions. These porous networks also possess moderate H2 storage capacity (1.35 wt% at 1 bar and 77 K) and high isosteric heat of H2 adsorption (10.3 kJ mol−1). Our finding provides a new targeted route to control the porosities and functionalities of microporous polymers for efficient gas uptake.
Co-reporter:Sophie Kuecken;Amitava Acharjya;Linjie Zhi;Michael Schwarze;Reinhard Schomäcker;Arne Thomas
Chemical Communications 2017 vol. 53(Issue 43) pp:5854-5857
Publication Date(Web):2017/05/30
DOI:10.1039/C7CC01827D
A fast and facile route for the optimization of covalent triazine frameworks (CTFs) for photocatalytic hydrogen production is presented. Within 10 minutes a CTF with low photocatalytic activity can be converted into a highly active photocatalyst. Optimized CTF catalysts show an average hydrogen evolution rate of 1072 μmol h−1 g−1 under visible light (>420 nm).
Co-reporter:Matthias Trunk;Anna Herrmann;Dr. Hakan Bildirir;Dr. Ali Yassin;Dr. Johannes Schmidt ;Dr. Arne Thomas
Chemistry - A European Journal 2016 Volume 22( Issue 21) pp:7179-7183
Publication Date(Web):
DOI:10.1002/chem.201600783
Abstract
A modified one-pot Sonogashira cross-coupling reaction based on a copper-free methodology has been applied for the synthesis of conjugated microporous poly(aryleneethynylene) networks (CMPs) from readily available iodoarylenes and 1,3,5-triethynylbenzene. The polymerization reactions were carried out by using equimolar amounts of halogen and terminal alkyne moieties with extremely small loadings of palladium catalyst as low as 0.65 mol %. For the first time, CMPs with rigorously controlled structures were obtained without any indications of side reactions, as proven by FTIR and solid-state NMR spectroscopy, while showing Brunauer–Emmett–Teller (BET) surface areas higher than any poly(aryleneethynylene) network reported before, reaching up to 2552 m2 g−1.
Co-reporter:Sophie Kuecken, Johannes Schmidt, Linjie Zhi and Arne Thomas
Journal of Materials Chemistry A 2015 vol. 3(Issue 48) pp:24422-24427
Publication Date(Web):2015/11/06
DOI:10.1039/C5TA07408H
The conversion of an amorphous, non-porous polymer network into an ordered, microporous covalent organic framework under ionothermal conditions is presented. The amorphous polymer network is prepared by trimerization of carbonitrile monomers using strong Broensted acids. In a second step the polymer network is converted into a porous covalent triazine framework (CTF) under ionothermal conditions, i.e. in molten zinc chloride. This two-step process largely facilitates the synthesis of CTFs as the application of a polymeric precursor avoids early evaporation of small organic compounds at the high temperatures of the ionothermal process and therefore no evacuated and sealed quartz ampoules have to be used, which makes the CTF synthesis easier, safer and scalable.
Co-reporter:Daniel Becker, Nina Heidary, Marius Horch, Ulrich Gernert, Ingo Zebger, Johannes Schmidt, Anna Fischer and Arne Thomas
Chemical Communications 2015 vol. 51(Issue 20) pp:4283-4286
Publication Date(Web):05 Feb 2015
DOI:10.1039/C4CC09637A
Covalent attachment of a microporous polymer network (MPN) on a gold surface is presented. A functional bromophenyl-based self-assembled monolayer (SAM) formed on the gold surface acts as co-monomer in the polymerisation of the MPN yielding homogeneous and robust coatings. Covalent binding of the films to the electrode is confirmed by SEIRAS measurements.
Co-reporter:Dr. Elham Baktash;Patrick Littlewood;Johannes Pfrommer; Reinhard Schomäcker; Matthias Driess; Arne Thomas
ChemCatChem 2015 Volume 7( Issue 8) pp:1280-1284
Publication Date(Web):
DOI:10.1002/cctc.201402983
Abstract
Supported NiO nanoparticles (NPs) were prepared by impregnation of mesoporous silica SBA-15 with a molecular, metalorganic [Ni4O4] cubane cluster as precursor. By using this ligand-stabilized Ni cluster, deposition of four Ni ions in close proximity on the silica support was achieved; this resulted in the formation of small and highly dispersed NiO NPs after heat treatment. These clusters were shown to have a significant influence on the formation of NiO NPs compared to a conventional Ni(OAc)2 precursor. After a further reduction step, the materials were used as catalysts for the dry reforming of methane, which showed that preorganization of the Ni atoms on the support surface had a beneficial effect on the methane conversion rate.
Co-reporter:Dirk Hollmann, Michael Karnahl, Stefanie Tschierlei, Kamalakannan Kailasam, Matthias Schneider, Jörg Radnik, Kathleen Grabow, Ursula Bentrup, Henrik Junge, Matthias Beller, Stefan Lochbrunner, Arne Thomas, and Angelika Brückner
Chemistry of Materials 2014 Volume 26(Issue 4) pp:1727
Publication Date(Web):January 31, 2014
DOI:10.1021/cm500034p
Photocatalytic hydrogen evolution rates and structural properties as well as charge separation, electron transfer, and stabilization have been analyzed in advanced sol–gel-derived carbon nitrides (SG-CN) pyrolyzed at different temperatures (350–600 °C) and in bulk polymeric carbon nitride reference samples (CN) by XRD, XPS, FTIR, UV–vis, Raman, and photoluminescence as well as by in situ EPR spectroscopy. SG-CN samples show about 20 times higher H2 production rates than bulk CN. This is due to their porous structure, partial disorder, and high surface area which favor short travel distances and fast trapping of separated electrons on the surface where they are available for reaction with protons. In contrast, most of the excited electrons in bulk polymeric CN return quickly to the valence band upon undesired emission of light, which is responsible for their low catalytic activity.
Co-reporter:Sabrina Fischer, Aneta Schimanowitz, Robert Dawson, Irena Senkovska, Stefan Kaskel and Arne Thomas
Journal of Materials Chemistry A 2014 vol. 2(Issue 30) pp:11825-11829
Publication Date(Web):29 May 2014
DOI:10.1039/C4TA02022G
Microporous organic polymer networks with weakly coordinating cations in their backbone have been synthesised by metal catalysed C–C bond forming reactions. A functionalised tetraphenylphosphonium ion was synthesised and successfully used as a tecton in a co-polymerisation with tetrakis(4-bromophenyl) methane using nickel catalysed Yamamoto coupling and with triethynylbenzene in a palladium catalysed Songashira–Hagihara reaction. The microporous materials showed an apparent BET surface area of 1455 m2 g−1 and 540 m2 g−1, respectively. The Yamamoto product provide a CO2 uptake of 2.49 mmol g−1 at 273 K and 1 bar. After ion exchange with chloride CO2 uptake is further increased to 2.85 mmol g−1.
Co-reporter:Hakan Bildirir;Dr. Jens Peter Paraknowitsch ;Dr. Arne Thomas
Chemistry - A European Journal 2014 Volume 20( Issue 31) pp:9543-9548
Publication Date(Web):
DOI:10.1002/chem.201402278
Abstract
Conjugated microporous polymer networks have been prepared from the strong electron donor tetrathiafulvalene (TTF) and 1,3,5-triethynylbenzene (TEB) by using the Sonogashira–Hagihara cross-coupling reaction. Optimization of reaction conditions yields polymers with surface areas of up to 434 m2 g−1. The strong electron-donating properties of the network can be proven by iodine exposure. Structural and electronic changes due to formation of the charge-transfer salt from TTFs in the porous network and iodine within the pores are investigated.
Co-reporter:Young-Si Jun;Eun Zoo Lee;Xinchen Wang;Won Hi Hong;Galen D. Stucky;Arne Thomas
Advanced Functional Materials 2013 Volume 23( Issue 29) pp:3661-3667
Publication Date(Web):
DOI:10.1002/adfm.201203732
Abstract
Graphitic carbon nitride (g-CN) is a promising heterogeneous metal-free catalyst for organic photosynthesis, solar energy conversion, and photodegradation of pollutants. Its catalytic performance is easily adjustable by modifying texture, optical, and electronic properties via nanocasting, doping, and copolymerization. However, simultaneous optimization has yet to be achieved. Here, a facile synthesis of mesoporous g-CN using molecular cooperative assembly between triazine molecules is reported. Flower-like, layered spherical aggregates of melamine cyanuric acid complex (MCA) are formed by precipitation from equimolecular mixtures in dimethyl sulfoxide (DMSO). Thermal polycondensation of MCA under nitrogen at 550 °C produces mesoporous hollow spheres comprised of tri-s-triazine based g-CN nanosheets (MCA-CN) with the composition of C3N4.14H1.98. The layered structure succeeded from MCA induces stronger optical absorption, widens the bandgap by 0.16 eV, and increases the lifetime of photoexcited charge carriers by twice compared to that of the bulk g-CN, while the chemical structure remains similar to that of the bulk g-CN. As a result of these simultaneous modifications, the photodegradation kinetics of rhodamine B on the catalyst surface can be improved by 10 times.
Co-reporter:Phisan Katekomol, Jérôme Roeser, Michael Bojdys, Jens Weber, and Arne Thomas
Chemistry of Materials 2013 Volume 25(Issue 9) pp:1542
Publication Date(Web):March 3, 2013
DOI:10.1021/cm303751n
A novel covalent triazine framework (CTF-0) was prepared by trimerization of 1,3,5-tricyanobenzene in molten ZnCl2. The monomer/ZnCl2 ratio, the reaction time, and temperature significantly influence the structure and porosity of such networks. XRD measurements revealed that crystalline frameworks can be formed with surface areas around 500 m2·g–1 and high CO2 uptakes. Increasing the reaction temperature yielded an amorphous material with an enlarged surface area of 2000 m2·g–1. This material showed good catalytic activity for CO2 cycloaddition.Keywords: carbon dioxide sorption/utilization; covalent organic framework; heterogeneous catalysis; microporous polymers; organic carbonates;
Co-reporter:Xiao Xie, Torsten Otremba, Patrick Littlewood, Reinhard Schomäcker, and Arne Thomas
ACS Catalysis 2013 Volume 3(Issue 2) pp:224
Publication Date(Web):December 26, 2012
DOI:10.1021/cs3003963
Silica supported nanoparticles of nickel manganese oxide, Ni0.2Mn0.8O, were prepared in a one-pot approach, combining co-precipitation and sol–gel chemistry. This approach enables the preparation of small ternary oxide crystallites evenly dispersed on porous silica. The resulting materials were used as catalyst for dry reforming of methane (DRM), and show a much higher activity as the reference bulk material prepared from conventional co-precipitation. Notably, the catalyst shows a remarkable activity even at low temperatures for DRM, thus nearly reaching thermodynamic equilibrium at 500 °C.Keywords: activation; carbon dioxide; dry reforming; heterogeneous catalysis; metal oxide catalyst; methane
Co-reporter:Kamalakannan Kailasam;Johannes Schmidt;Hakan Bildirir;Guigang Zhang;Siegfried Blechert;Xinchen Wang;Arne Thomas
Macromolecular Rapid Communications 2013 Volume 34( Issue 12) pp:1008-1013
Publication Date(Web):
DOI:10.1002/marc.201300227
Co-reporter:Elham Baktash, Ivelina Zaharieva, Marc Schröder, Caren Goebel, Holger Dau and Arne Thomas
Dalton Transactions 2013 vol. 42(Issue 48) pp:16920-16929
Publication Date(Web):03 Sep 2013
DOI:10.1039/C3DT51693H
In nature, photosynthetic water oxidation is efficiently catalysed at a protein-bound μ-oxido Mn4Ca cluster. This cluster consists of earth abundant, non-toxic elements and serves as a paragon for development of synthetic catalysts. In this study we developed porous calcium–manganese oxides with a unique foam-like nanostructure prepared via a facile and robust synthetic route using cyanamide as a porogen. A series of such oxide foams annealed at different temperatures was characterized by TEM, SEM, XRD, N2 physisorption, and X-ray absorption spectroscopy (XAS) in order to correlate crystallinity, atomic structure, surface area and oxidation state of the materials with catalytic activity. Some of the resulting Ca–Mn oxides show high activity as catalysts for water oxidation in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant. An amorphous calcium–manganese-oxide foam with 130 m2 g−1 surface area and Mn oxidation state of +3.6 was identified to be most active; its activity is superior to previously reported Ca–Mn oxides. At the atomic level, this material shares structural motifs with the biological paragon as revealed by dual-edge XAS at the Mn and Ca K-edge. Rather than nanostructure and surface area, the atomic structure of the Ca–Mn oxide and the extent of structural order appear to be crucial determinants of catalytic activity. Fully disordered low-valent Mn materials as well as high-valent but crystalline Mn–Ca oxides are unreactive. Highly disordered variants of layered manganese oxide with Ca and water molecules interfacing layer fragments are most reactive.
Co-reporter:Sabrina Fischer;Dr. Johannes Schmidt;Dr. Peter Strauch; Arne Thomas
Angewandte Chemie 2013 Volume 125( Issue 46) pp:12396-12400
Publication Date(Web):
DOI:10.1002/ange.201303045
Co-reporter:Sabrina Fischer;Dr. Johannes Schmidt;Dr. Peter Strauch; Arne Thomas
Angewandte Chemie International Edition 2013 Volume 52( Issue 46) pp:12174-12178
Publication Date(Web):
DOI:10.1002/anie.201303045
Co-reporter:Dipti S. Kundu;Dr. Johannes Schmidt;Dr. Christian Bleschke;Dr. Arne Thomas;Dr. Siegfried Blechert
Angewandte Chemie International Edition 2012 Volume 51( Issue 22) pp:5456-5459
Publication Date(Web):
DOI:10.1002/anie.201109072
Co-reporter:Dipti S. Kundu;Dr. Johannes Schmidt;Dr. Christian Bleschke;Dr. Arne Thomas;Dr. Siegfried Blechert
Angewandte Chemie 2012 Volume 124( Issue 22) pp:5552-5555
Publication Date(Web):
DOI:10.1002/ange.201109072
Co-reporter:Kamalakannan Kailasam, Jan Dirk Epping, Arne Thomas, Sebastian Losse and Henrik Junge
Energy & Environmental Science 2011 vol. 4(Issue 11) pp:4668-4674
Publication Date(Web):07 Oct 2011
DOI:10.1039/C1EE02165F
Mesoporous carbon nitrides, silicas and their composites have been prepared by a combined sol–gel and thermal condensation approach. Precursors for the carbon nitride (cyanamide) and silica (TEOS) are mixed and condensed simultaneously. After condensation and heat treatment it is observed that the carbon nitride and silica formed highly interpenetrating mesophases which leads either to the formation of mesoporous carbon nitride or silica after selective removal of one of the phases. Importantly, the carbon nitride preserves its graphitic stacking even in the spatial confinement introduced by the surrounding silica phase. As both precursors are liquids this approach allows convenient shaping into thin and thick films or monoliths of mesoporous carbon nitrides. Enhanced photocatalytic activity is observed for the production of hydrogen from water when these mesoporous carbon nitrides are applied as photocatalyst in comparison to the bulk, but also to other mesoporous carbon nitrides, prepared by the reported two-step, hard templating approach.
Co-reporter:Junjiang Zhu, Kamalakannan Kailasam, Anna Fischer, and Arne Thomas
ACS Catalysis 2011 Volume 1(Issue 4) pp:342
Publication Date(Web):March 2, 2011
DOI:10.1021/cs100153a
Supported cobalt oxide nanoparticles (NPs) have been prepared by wetness impregnation on different supports and subsequent heat treatment in argon at 350 °C for 2 h. The thus prepared cobalt oxide (Co3O4) can be well dispersed on carbonaceous materials such as activated carbon (AC) and covalent trizaine frameworks (CTF), with average particle sizes below 5 nm. The catalytic performance of supported Co3O4 NPs was tested by aerobic oxidation of alcohols in liquid phase. The results show that AC supported Co3O4 NPs, Co3O4/AC, exhibit ∼100% conversions for alcohol oxidation and can be reused for at least 4 runs without appreciable loss of activity, when a thermal regeneration step is carried out, suggesting that the Co3O4 NPs are well embedded and stabilized on the support, making Co3O4/AC a promising catalyst for aerobic oxidation of alcohols in liquid phase.Keywords: activated carbon; alcohol oxidation; cobalt oxide; liquid phase; nanoparticles
Co-reporter:Junjiang Zhu, Kamalakannan Kailasam, Xiao Xie, Reinhard Schomaecker, and Arne Thomas
Chemistry of Materials 2011 Volume 23(Issue 8) pp:2062
Publication Date(Web):March 31, 2011
DOI:10.1021/cm1028639
The influence of poly(vinyl alcohol) (PVA) in the synthesis of SBA-15 was investigated. It was found that, by the addition of PVA, the surface area and porosity of SBA-15 is increased, while the structure and size of the mesopores remain unchanged. Nitrogen sorption measurements indicate that PVA introduces additional pores with pore sizes of around 2 nm into the pore wall. Thus, a simple way of improving the porosity of mesoporous silica is presented that could enhance transport of substrates through the porous system, important for catalytic applications and also beneficial for replication and nanocasting purposes. We, furthermore, show that a heterogeneous catalyst, Pt/SBA-15, with high surface area can be prepared by the addition of PVA-stabilized platinum nanoparticle sols.Keywords: cyclooctadiene hydrogenation; heterogeneous catalysis; mesoporous silica; platinum; PVA; SBA-15;
Co-reporter:Yilmaz Aksu, Stefano Frasca, Ulla Wollenberger, Matthias Driess, and Arne Thomas
Chemistry of Materials 2011 Volume 23(Issue 7) pp:1798
Publication Date(Web):March 4, 2011
DOI:10.1021/cm103087p
The preparation of porous, i.e., high surface area electrodes from transparent conducting oxides, is a valuable goal in materials chemistry as such electrodes can enable further development of optoelectronic, electrocatalytic, or bioelectronic devices. In this work the first tin-rich mesoporous indium tin oxide is prepared using the molecular heterobimetallic single-source precursor, indium tin tris-tert-butoxide, together with an appropriate structure-directing template, yielding materials with high surface areas and tailorable pore size. The resulting mesoporous tin-rich ITO films show a high and durable electrical conductivity and transparency, making them interesting materials for hosting electroactive biomolecules such as proteins. In fact, its unique performance in bioelectronic applications has been demonstrated by immobilization of high amounts of cytochrome c into the mesoporous film which undergo redox processes directly with the conductive electrode material.Keywords: bioelectrochemistry; cytochrome c; device; electrode; indium tin oxide ITO;
Co-reporter:Carine E. Chan-Thaw, Alberto Villa, Phisan Katekomol, Dangsheng Su, Arne Thomas and Laura Prati
Nano Letters 2010 Volume 10(Issue 2) pp:537-541
Publication Date(Web):January 19, 2010
DOI:10.1021/nl904082k
An important goal in the preparation of highly active supported metal particles is the enhancement of the metal support interaction, providing a more stable catalyst, especially for liquid phase reactions as the leaching and reconstruction of the active phase causes deactivation. In this work, a covalent triazine framework (CTF) as support for Pd nanoparticles is compared to activated carbon (AC), the typical support used in liquid phase reactions. The results indicate that the presence of the N-heterocyclic moieties on the surface of the frameworks is beneficial for improving the stability of Pd nanoparticles during the liquid phase glycerol oxidation. Pd/CTF showed better activity and in particular better stability when compared to Pd supported on activated carbon (AC).
Co-reporter:Kamalakannan Kailasam, Young-Si Jun, Phisan Katekomol, Jan Dirk Epping, Won Hi Hong and Arne Thomas
Chemistry of Materials 2010 Volume 22(Issue 2) pp:428
Publication Date(Web):December 21, 2009
DOI:10.1021/cm9029903
Mesoporous melamine resins have been prepared using hexamethoxymethyl melamine (HMMM) as monomer and block-co-polymer Pluronic F127 as template. At acidic conditions, HMMM condenses into melamine resins, replicating the mesophases formed by the block-co-polymer template. The template can be removed by solvent extraction, yielding mesoporous melamine resins with surface areas of up to 258 m2/g and pore diameters of 7.8 nm. At a HMMM/F127 weight ratio of 1:1 an ordered mesoporous melamine resin is observed exhibiting a 2d hexagonal arrangement of cylindrical pores. The simplicity of the synthesis of these mesoporous films allows the large scale production of the materials, for example, in the form of free-standing films.
Co-reporter:Jens Peter Paraknowitsch Dr.;Arne Thomas ;Markus Antonietti
ChemSusChem 2010 Volume 3( Issue 2) pp:223-225
Publication Date(Web):
DOI:10.1002/cssc.200900168
Co-reporter:Dr. Arne Thomas
Angewandte Chemie 2010 Volume 122( Issue 45) pp:8506-8523
Publication Date(Web):
DOI:10.1002/ange.201000167
Abstract
Dieser Aufsatz soll einen Überblick über die jüngsten Entwicklungen auf dem Gebiet der porösen organisch-anorganischen oder rein organischen Funktionsmaterialien geben. Verschiedene Möglichkeiten zum Einbau organischer Gruppen, die eine chemische oder physikalische Funktion aufweisen, in poröse Netzwerke werden diskutiert. Speziell sollen hier Materialien besprochen werden, bei denen die organischen funktionellen Gruppen ein tragender Bestandteil der Porenwände sind. Durch diesen Ansatz kann die Zahl der organischen Gruppen im Netzwerk prinzipiell bis zu dem Punkt erhöht werden, an dem das poröse Material rein organisch wird.
Co-reporter:Dr. Arne Thomas
Angewandte Chemie International Edition 2010 Volume 49( Issue 45) pp:8328-8344
Publication Date(Web):
DOI:10.1002/anie.201000167
Abstract
This Review aims to give an overview of recent research in the area of porous, organic–inorganic and purely organic, functional materials. Possibilities for introducing organic groups that exhibit chemical and/or physical functions into porous materials will be described, with a focus on the incorporation of such functional groups as a supporting part of the pore walls. The number of organic groups in the network can be increased such that porous, purely organic materials are obtained.
Co-reporter:DangSheng Su Dr.;Jian Zhang Dr.;Benjamin Frank Dr.;Arne Thomas ;Xinchen Wang Dr.;Jens Paraknowitsch Dr.;Robert Schlögl
ChemSusChem 2010 Volume 3( Issue 2) pp:169-180
Publication Date(Web):
DOI:10.1002/cssc.200900180
Abstract
The current established catalytic processes used in chemical industries use metals, in many cases precious metals, or metal oxides as catalysts. These are often energy-consuming and not highly selective, wasting resources and producing greenhouse gases. Metal-free heterogeneous catalysis using carbon or carbon nitride is an interesting alternative to some current industrialized chemical processes. Carbon and carbon nitride combine environmental acceptability with inexhaustible resources and allow a favorable management of energy with good thermal conductivity. Owing to lower reaction temperatures and increased selectivity, these catalysts could be candidates for green chemistry with low emission and an efficient use of the chemical feedstock. This Review highlights some recent promising activities and developments in heterogeneous catalysis using only carbon and carbon nitride as catalysts. The state-of-the-art and future challenges of metal-free heterogeneous catalysis are also discussed.
Co-reporter:M. Yildiz, Y. Aksu, U. Simon, T. Otremba, K. Kailasam, C. Göbel, F. Girgsdies, O. Görke, F. Rosowski, A. Thomas, R. Schomäcker, S. Arndt
Applied Catalysis A: General (5 September 2016) Volume 525() pp:168-179
Publication Date(Web):5 September 2016
DOI:10.1016/j.apcata.2016.06.034
Co-reporter:Robin J. White ; Anna Fischer ; Caren Goebel ;Arne Thomas
Journal of the American Chemical Society () pp:
Publication Date(Web):January 7, 2014
DOI:10.1021/ja411586h
A generalized synthesis of high-quality, mesoporous zeolite (e.g., MFI-type) nanocrystals is presented, based on a biomass-derived, monolithic N-doped carbonaceous template. As an example, ZSM-5 single crystals with desirable large-diameter (12–16 nm) intracrystalline mesopores are synthesized. The platform provides scope to optimize template dimensions and chemistry for the synthesis of a range of micro-/mesoporous crystalline zeolites in a cost-effective and highly flexible manner.
Co-reporter:Sophie Kuecken, Amitava Acharjya, Linjie Zhi, Michael Schwarze, Reinhard Schomäcker and Arne Thomas
Chemical Communications 2017 - vol. 53(Issue 43) pp:NaN5857-5857
Publication Date(Web):2017/05/08
DOI:10.1039/C7CC01827D
A fast and facile route for the optimization of covalent triazine frameworks (CTFs) for photocatalytic hydrogen production is presented. Within 10 minutes a CTF with low photocatalytic activity can be converted into a highly active photocatalyst. Optimized CTF catalysts show an average hydrogen evolution rate of 1072 μmol h−1 g−1 under visible light (>420 nm).
Co-reporter:Nicolas Chaoui, Matthias Trunk, Robert Dawson, Johannes Schmidt and Arne Thomas
Chemical Society Reviews 2017 - vol. 46(Issue 11) pp:NaN3321-3321
Publication Date(Web):2017/04/19
DOI:10.1039/C7CS00071E
Microporous polymers are covalently bound, entirely organic materials which possess very high surface areas. These materials have been intensively studied within recent years and various interesting properties and possible applications have been discovered and described. This review article starts with the question, what makes microporous polymers special and are there certain features which differentiate them from other microporous materials? Indeed, there are some special structural and functional features found in microporous polymers which make them really unique and merit further exploration. We focus here on microporous polymers which are solution-processable, can be produced as thin films on electrodes by oxidative polymerizations, are π-conjugated organic semiconductors, or which provide the possibility to introduce and exploit distinct functional groups in an otherwise non-functional highly porous environment. Emerging applications for these microporous polymers which make explicit use of these unique features are further presented.
Co-reporter:Daniel Becker, Nina Heidary, Marius Horch, Ulrich Gernert, Ingo Zebger, Johannes Schmidt, Anna Fischer and Arne Thomas
Chemical Communications 2015 - vol. 51(Issue 20) pp:NaN4286-4286
Publication Date(Web):2015/02/05
DOI:10.1039/C4CC09637A
Covalent attachment of a microporous polymer network (MPN) on a gold surface is presented. A functional bromophenyl-based self-assembled monolayer (SAM) formed on the gold surface acts as co-monomer in the polymerisation of the MPN yielding homogeneous and robust coatings. Covalent binding of the films to the electrode is confirmed by SEIRAS measurements.
Co-reporter:Sabrina Fischer, Aneta Schimanowitz, Robert Dawson, Irena Senkovska, Stefan Kaskel and Arne Thomas
Journal of Materials Chemistry A 2014 - vol. 2(Issue 30) pp:NaN11829-11829
Publication Date(Web):2014/05/29
DOI:10.1039/C4TA02022G
Microporous organic polymer networks with weakly coordinating cations in their backbone have been synthesised by metal catalysed C–C bond forming reactions. A functionalised tetraphenylphosphonium ion was synthesised and successfully used as a tecton in a co-polymerisation with tetrakis(4-bromophenyl) methane using nickel catalysed Yamamoto coupling and with triethynylbenzene in a palladium catalysed Songashira–Hagihara reaction. The microporous materials showed an apparent BET surface area of 1455 m2 g−1 and 540 m2 g−1, respectively. The Yamamoto product provide a CO2 uptake of 2.49 mmol g−1 at 273 K and 1 bar. After ion exchange with chloride CO2 uptake is further increased to 2.85 mmol g−1.
Co-reporter:Sophie Kuecken, Johannes Schmidt, Linjie Zhi and Arne Thomas
Journal of Materials Chemistry A 2015 - vol. 3(Issue 48) pp:NaN24427-24427
Publication Date(Web):2015/11/06
DOI:10.1039/C5TA07408H
The conversion of an amorphous, non-porous polymer network into an ordered, microporous covalent organic framework under ionothermal conditions is presented. The amorphous polymer network is prepared by trimerization of carbonitrile monomers using strong Broensted acids. In a second step the polymer network is converted into a porous covalent triazine framework (CTF) under ionothermal conditions, i.e. in molten zinc chloride. This two-step process largely facilitates the synthesis of CTFs as the application of a polymeric precursor avoids early evaporation of small organic compounds at the high temperatures of the ionothermal process and therefore no evacuated and sealed quartz ampoules have to be used, which makes the CTF synthesis easier, safer and scalable.
Co-reporter:Elham Baktash, Ivelina Zaharieva, Marc Schröder, Caren Goebel, Holger Dau and Arne Thomas
Dalton Transactions 2013 - vol. 42(Issue 48) pp:NaN16929-16929
Publication Date(Web):2013/09/03
DOI:10.1039/C3DT51693H
In nature, photosynthetic water oxidation is efficiently catalysed at a protein-bound μ-oxido Mn4Ca cluster. This cluster consists of earth abundant, non-toxic elements and serves as a paragon for development of synthetic catalysts. In this study we developed porous calcium–manganese oxides with a unique foam-like nanostructure prepared via a facile and robust synthetic route using cyanamide as a porogen. A series of such oxide foams annealed at different temperatures was characterized by TEM, SEM, XRD, N2 physisorption, and X-ray absorption spectroscopy (XAS) in order to correlate crystallinity, atomic structure, surface area and oxidation state of the materials with catalytic activity. Some of the resulting Ca–Mn oxides show high activity as catalysts for water oxidation in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant. An amorphous calcium–manganese-oxide foam with 130 m2 g−1 surface area and Mn oxidation state of +3.6 was identified to be most active; its activity is superior to previously reported Ca–Mn oxides. At the atomic level, this material shares structural motifs with the biological paragon as revealed by dual-edge XAS at the Mn and Ca K-edge. Rather than nanostructure and surface area, the atomic structure of the Ca–Mn oxide and the extent of structural order appear to be crucial determinants of catalytic activity. Fully disordered low-valent Mn materials as well as high-valent but crystalline Mn–Ca oxides are unreactive. Highly disordered variants of layered manganese oxide with Ca and water molecules interfacing layer fragments are most reactive.