Ruthenium‐Catalyzed Deconstruction of Polyolefins: A Strategy to Up‐cycle Waste Polyethylene to Value‐Added AlkenePadhi, Ganeshdev; Khopade, Kishor V.; Moyilla, Nageswararao; Rangappa, Raghavendrakumar; Chikkali, Samir H.; Barsu, Nagaraju
doi: 10.1002/anie.202422609pmid: 39841863
Synthesis of value‐added products from post‐consumer waste polyolefins is fascinating as well as challenging. Here we report ruthenium‐catalyzed up‐cycling of the polyethylene to long‐chain alkene derivatives. The developed methodology mainly involves two steps i.e., dehydrogenation of polyethylene through hydrogen atom transfer and its metathesis using the HG‐II catalyst. The dehydrogenation of polyethylene using ruthenium catalysis derived up to 3.38 %, of double bonds; with 90 % of the recovered polyolefin material. The obtained unsaturated polyethylene was subjected to cross‐metathesis with ethylene using HG‐II catalytic system. This resulted in the synthesis of predominantly dodecene (C12) derivatives, with 58 % selectivity, along with other derivatives of varying chain lengths. The overall reaction produced terminal and internal olefins in the ratio 1:0.8 respectively. The dehydrogenation of polyethylene and its deconstruction was confirmed by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The origin of C12 selectivity has been demonstrated by control experiments. The scope of the methodology was extended to post‐consumer waste polyethylene which gave high conversion to value‐added dodecene derivatives as a major product.
COF‐Assisted Construction of Steric Mass‐Charge Channels to Boost Activity for High‐Performance Fuel CellsWen, Guobin; Sun, Liancheng; Qin, Yanzhou; Liu, Shengnan; Ma, Luyao; Zhang, Ningce; Liu, Shuxuan; Yin, Yan; Ren, Bohua; Wang, Shuangyin
doi: 10.1002/anie.202424179pmid: 39831353
The two‐dimensional lamellar materials disperse platinum sites and minimize noble‐metal usage for fuel cells, while mass transport resistance at the stacked layers spurs device failure with a significant performance decline in membrane electrode assembly (MEA). Herein, we implant porous and rigid sulfonated covalent organic frameworks (COF) into the graphene‐based catalytic layer for the construction of steric mass‐charge channels, which highly facilitates the activity of oxygen reduction reactions in both the rotating disk electrode (RDE) measurements and MEA device tests. Specifically, the normalized mass activity is remarkably boosted by 3.7 times to 1.56 A mgpt−1 after additions of suitable COF modifications in the RDE tests. Especially, an excellent maximum power density of 1.015 W cm−2 is realized on the MEA in H2/Air condition, representing a 22 % improvement through such constructions of steric mass‐charge channels. Meanwhile, the open‐circuit voltage of fuel cells demonstrates only 0.8 % reductions after 10,000 cycles of stability tests. We further extended such methodology of constructing mass‐charge channels to granular PtCo and commercial Pt/C catalysts, which demonstrates a significant impetus for stimulating the catalytic activity in fuel cells.
Tiny‐Ligand Solvation Electrolyte Enabled Fast‐Charging Aqueous BatteriesShang, Yanxin; Chen, Nan; Li, Yuejiao; Chen, Shi; Li, Zhujie; Li, Shengxi; Ren, Xuening; Ye, Yusheng; Li, Li; Wu, Feng; Chen, Renjie
doi: 10.1002/anie.202423808pmid: N/A
The H‐bond network among H2O molecules enables ultrafast diffusion of H+ and OH− via a hopping mechanism, making aqueous batteries attractive competitors for next‐generation fast‐charging energy storages. Ideal aqueous electrolyte for the widely used lithium‐ion batteries is expected to have the wide electrochemical stability window (>5 volts), fast charging (≤15 minutes) without gas evolution, and low cost. However, the hydrogen evolution reaction (HER) associated with narrow voltage window of water (1.23 V) limits their practical applications. Herein, we built a new guideline for designing tiny‐ligand electrolytes by utilizing sterically hindered groups with low binding energy. Cosolvent tetraethyl orthocarbonate (TEOC), with large‐sized ethoxy groups and hydrogen‐bond‐captured ability, forces free H2O and anion TFSI− into the Li+ first solvation shell. Hence, inhibition of HER takes place by means of immobilized H2O activity and formation of hydrogen‐bonding networks —C−O⋅⋅⋅H between TEOC and H2O. This unique structure with ultra‐small sheath volume thereby facilitates the formation of LiF‐rich SEI and fast ion‐conduction. The lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in TEOC/H2O electrolyte exhibits wide electrochemical window of 5.7 V, enabling LiMn2O4/Li4Ti5O12 pouch cells to achieve 1200 cycles under rapid 10 C rate. This engineering of tiny‐ligand solvation opens new pathways for developing advanced electrolyte that balance performance with sustainability.
Towards Surface‐Enhanced Homogeneous Catalysis: Tailoring the Enrichment of Metal Complexes at Ionic Liquid SurfacesHemmeter, Daniel; Haumann, Marco; Williams, Federico J.; Koller, Thomas M.; Wasserscheid, Peter; Meyer, Karsten; Maier, Florian; Steinrück, Hans‐Peter
doi: 10.1002/anie.202422693pmid: 39972678
When talking about homogeneous catalyst systems, it has long been assumed that the system at hand consists of a transition metal complex in solution with the liquid interface representing the composition of the bulk solution. Now, in light of considerable developments in the study of metal complexes dissolved in ionic liquids with their negligible vapor pressures, more detailed studies of the composition at the liquid/gas interface became possible. These investigations revealed pronounced surface enrichment and segregation effects of high relevance for practical applications. This article reviews recent advancements in tailoring the interfacial composition of ionic liquid‐based catalytic systems. A particular focus is dedicated to surface enrichment phenomena, and a variety of parameters are presented for deliberate control of the local concentration of the complexes at the surface, that is, the nature of the ligands, the bulk concentration, the temperature, and the nature of the IL solvent. As experimental methods, angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) and vacuum‐based pendant‐drop surface tension measurements were applied. The reviewed results are intended to provide the basis for the advancement of catalytic systems with high surface areas, such as in supported ionic liquid phase (SILP) catalysis, where the interface design is directly interconnected with catalytic performance.
Defect‐Induced Electron Localization Promotes D2O Dissociation and Nitrile Adsorption for Deuterated AminesLi, Rui; He, Meng; Cheng, Chuanqi; Chen, Fanpeng; Yang, Lijun; Cui, Jian‐Zhong; Liu, Cuibo; Zhang, Bin
doi: 10.1002/anie.202424039pmid: 39806818
Electrochemical reductive deuteration of nitriles is a promising strategy for synthesizing deuterated amines with D2O as the deuterated source. However, this reaction suffers from high overpotentials owing to the sluggish D2O dissociation kinetics and high thermodynamic stability of the C≡N triple bond. Here, low‐coordinated copper (LC−Cu) is designed to decrease the overpotential for the electrosynthesis of the precursor of Melatonin‐d4, 5‐methoxytryptamine‐d4, by 100 mV with a 68 % yield (Faradaic efficiency), which is 4 times greater than that of high‐coordinated copper (HC−Cu). The low coordinated sites induced an enrichment of electrons to concentrate K+ ions hydrated deuterium water (K⋅D2O) and decrease the energy of the Volmer step via the polarization effect, leading to a continuous supplementation of *D for the reductive deuteration of nitriles. Moreover, the enhanced local electric field changes the adsorption configuration of nitriles from a semibridge model to a flat model, leading to faster reduction kinetics of nitriles with a high reaction rate at lower potentials. High deuterium incorporation, a wide substrate scope, and easy gram‐scale synthesis over LC−Cu at 300 mA rationalize the design concept. Furthermore, the enhanced antitumor and antioxidation effects of Melatonin‐d4 highlight the great promise of deuterated drugs.
Easily Water‐Synthesisable Iron‐Chloranilate Frameworks as High Energy and High‐Power Cathodes for Sustainable Alkali‐Ion BatteriesDurán‐Egido, Víctor; Darby, James P.; Cliffe, Matthew J.; Garitaonandia, José S.; Grande‐Fernández, Paloma; Morris, Andrew J.; Carretero‐González, Javier; Castillo‐Martínez, Elizabeth
doi: 10.1002/anie.202424416pmid: 39825770
Achieving high battery performance from low‐cost, easily synthesisable electrode materials is crucial for advancing energy storage technologies. Metal–organic frameworks (MOFs) combining inexpensive transition metals and organic ligands are promising candidates for high‐capacity cathodes. Iron‐chloranilate‐water frameworks are herein reported to be produced in aqueous media under mild conditions. Removal of reticular water from known [Fe2(CAN)3(H2O)4] ⋅ 4H2O yields a new supramolecular metal–organic framework (SMOF), [Fe2(CAN)3(H2O)4]. Removing coordination water, a new 2D honeycomb‐like MOF forms, Fe2(CAN)3, stable without counterions and solvent. This MOF adopts the unusual ABC layer‐stacking, as determined using a combination of ab initio random structure searching, electron diffraction, and Rietveld refinement of powder XRD data. Magnetometry, Mossbauer and Raman spectroscopy confirm that all three [Fe2(CAN)3(H2O)x]⋅yH2O phases contain HS‐Fe3+ and CAN2−, with magnetic ordering temperatures increasing (5→20 K) as the Fe−CAN connectivity increases. The SMOF and MOF show reversible (de)insertion of >4Li+/f.u. at average 2,59 V and 2,76 V vs Li+/Li, respectively. [Fe2(CAN)3] achieves 146 mAh/g at 1 C, thus specific energy (563 Wh/kg) and power (446 W/kg) in Li half‐cells competitive with conventional LiFePO4 (~580 Wh/kg and ~450 W/kg). Beyond Li, [Fe2(CAN)3] delivers 394 Wh/kg and 421 Wh/kg, for Na and K half‐cells respectively, becoming a competitive cathode for sustainable batteries.
Distinct Valence States of the [4Fe4S] Cluster Revealed in the Hydrogenase CrHydA1Heghmanns, Melanie; Yadav, Shalini; Boschmann, Sergius; Selve, Victor R.; Veliju, Astrit; Brocks, Claudia; Happe, Thomas; Pantazis, Dimitrios A.; Kasanmascheff, Müge
doi: 10.1002/anie.202424167pmid: 39828591
Iron‐sulfur clusters play a crucial role in electron transfer for many essential enzymes, including [FeFe]‐hydrogenases. This study focuses on the [4Fe4S] cluster ([4Fe]H) of the minimal [FeFe]‐hydrogenase from Chlamydomonas reinhardtii (CrHydA1) and employs advanced spectroscopy, site‐directed mutagenesis, molecular dynamics simulations, and QM/MM calculations. We provide insights into the complex electronic structure of [4Fe]H and its role in the catalytic reaction of CrHydA1, serving as paradigm for understanding [FeFe]‐hydrogenases. We identified at least two distinct species within the apo‐form of CrHydA1, designated 4Fe−R and 4Fe−A, with unique redox potentials and pH sensitivities. Our findings revealed that these species arise from a complex interplay of structural heterogeneity and valence isomer rearrangements, influenced by second‐sphere residues. We propose that the interconversion between 4Fe−R and 4Fe−A could provide control over electron transfer in the absence of accessory FeS clusters typically found in other [FeFe]‐hydrogenases. The insights gained from this study not only enhance our understanding of [FeFe]‐hydrogenases but also provide a crucial foundation for future investigations into analysis of other FeS clusters across diverse biological systems.