Chiral nematic mesoporous magnetic ferrites

Meseck, Georg R.; Terpstra, Andrea S.; Marenco, Armando J.; Trudel, Simon; Hamad, Wadood Y.; MacLachlan, Mark J.

doi:10.1039/c6tc04371b

Cited by 7 publications

(8 citation statements)

References 39 publications

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“…This method is advantageous compared to other loading techniques (e.g., incipient wetness loading), which often only achieve poor infiltration of the pore network and can require extensive surface modification of the silica template. [ 24a,27 ] Furthermore, unlike traditional loading methods, the films do not need to be crushed into fine powders to promote precursor absorption. This strategy to load pores of chiral mesoporous materials is attractive for its efficiency and ability to create large films.…”

Section: Resultsmentioning

confidence: 99%

“…[ 23 ] Moreover, CNMS has served as a platform to template mesoporous organic and inorganic materials with long‐range chirality. [ 12a,24 ] Surprisingly, there have only been a handful of reports demonstrating the synthesis of high surface area chiral metals despite their potential for chiral sensing, catalysis, and separation. [ 12a,25 ] Therefore, it is of great interest to use CNMS as a hard‐template to create chiral materials with high surface area.…”

Section: Introductionmentioning

confidence: 99%

“…Using a vacuum‐assisted loading technique, we achieved a high loading of precursor into the mesoporous template without the need for surface modification. The simplicity and speed of this method, and the ability to achieve deep pore penetration provides significant advantages over traditional loading methods, [ 24a ] and allows for the formation of a more complete chiral structure. Simple thermal treatment yields the metal oxide composites, which can then be extracted from the silica template while maintaining appreciable surface area and chirality.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Chiral Nematic Mesoporous Metal and Metal Oxide Nanocomposites and their Use as Heterogeneous Catalysts

et al. 2020

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We report the synthesis of chiral nematic mesoporous metal and metal oxide nanocomposites containing zinc or copper prepared through a vacuum‐assisted loading of the metal precursor into a chiral nematic mesoporous silica template followed by high‐temperature treatment. Significant metal loading into the template was achieved after a single loading cycle (up to 55 % of the pore volume) as confirmed by nitrogen sorption measurements. Growth of the metal nanoparticles was contained within the porous silica template, and subsequent removal of the template afforded free‐standing chiral nematic metal oxide films with surface areas up to 200 m2/g. To demonstrate the utility of these high surface area materials, we used the prepared CuO material as a heterogeneous catalyst for click reactions. Our prepared CuO showed excellent activity (95 % conversion after seven hours) when compared to commercially available CuO nanoparticles (20 % conversion after 24 hours) owing to its considerably higher surface area. Moreover, the prepared CuO material maintained high activity (>70 % conversion) after four cycles.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of Chiral Nematic Mesoporous Metal and Metal Oxide Nanocomposites and their Use as Heterogeneous Catalysts

et al. 2020

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“…PXRD patterns (Figure 1c) of the CoFe 2 O 4 /chitosan show diagnostic peaks at 32°, 37°, 45°, 60°, and 65°2θ corresponding to (220), (311), (400), (511), and (440) planes, respectively, for spinel cobalt ferrite (CoFe 2 O 4 ) crystals. [54] Characteristic peaks of crystalline chitosan are also observed. [13] SEM images (Figure 1f) show CoFe 2 O 4 nanoparticles attached onto chitosan nanofibrils.…”

Section: Resultsmentioning

confidence: 86%

“…[50,51] Such material preparation is exclusively due to the mimicry of Bouligand-type chitosan structure instead of the more widely used nanocellulose as previously reported by other researchers [52] and our group. [53,54] Here we present a bioinspired pathway for the fabrication of mesoporous CoFe 2 O 4 /C nanoflake materials with helical morphologies and we evaluate their electrochemical performance as free-standing LIB anodes.…”

Section: Introductionmentioning

confidence: 99%

Biomimetic Mesoporous Cobalt Ferrite/Carbon Nanoflake Helices for Freestanding Lithium‐Ion Battery Anodes

et al. 2020

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Structural biomimicry is a fascinating concept to explore hierarchically organized nanomaterials for mechanical structures, catalysis, sensing, and energy storage applications. Here we report the fabrication of biomimetic mesoporous cobalt ferrite/carbon nanoflake materials with helical morphologies and evaluate their electrochemical properties as free‐standing lithium‐ion battery (LIB) anodes. Iridescent chiral nematic mesoporous chitosan films obtained from crab shells were combined with binary metallic ions to afford helical cobalt ferrite/chitosan membranes. The cobalt ferrite/chitosan composites were thermally converted to cobalt ferrite/carbon replicas with hybrid nanoflakes arranged in a twisted Bouligand‐type mesoporous network. The structure of the materials was probed by electron microscopy, powder X‐ray diffraction, and Raman spectroscopy. We directly used these freestanding cobalt ferrite/carbon films as binder‐ and additive‐free LIB anodes, where they showed a first discharge capacity of 862 mAh g−1 (at 100 mA g−1), which faded during subsequent charge‐discharge cycles. Our work demonstrates a new potential use of chiroptical chitosan membranes to develop energy storage materials, a process that may be extended to other metal‐oxide based components.

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Homeotropic Concentric Helix Orientations in Chiral Nematic Cellulose Nanocrystal Films by Local Magnetic Fields

Jeong

et al. 2022

Advanced Optical Materials

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Many fascinating device applications of chiral nematic materials are determined by their helical axis orientations. Cellulose nanocrystals (CNCs) self‐assemble producing left‐handed chiral nematic films with predominant planar textures. While varied techniques have been exploited to tune the helical axis orientations, it remains challenging to produce concentrically aligned chiral nematic state. Herein, the authors report novel findings that left‐handed chiral nematic CNC films formed with homeotropic concentric helix orientations in the planar textures can be realized by local radial magnetic field‐directed self‐assembly of CNCs. These chiral nematic CNC films display left‐handed circular polarization patterns and transform spontaneous luminescence to right‐handed circularly polarized luminescence on both film plane and lateral surfaces owing to the underlying photonic bandgaps. These plane‐lateral chiroptical properties can be tuned simultaneously from the visible to the near‐infrared spectral regime. Their work presents a step towards the development of self‐organized chiroptical materials encoded with complex polarization features for photonic applications.

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Chiral nematic mesoporous magnetic ferrites

Cited by 7 publications

References 39 publications

Synthesis of Chiral Nematic Mesoporous Metal and Metal Oxide Nanocomposites and their Use as Heterogeneous Catalysts

Synthesis of Chiral Nematic Mesoporous Metal and Metal Oxide Nanocomposites and their Use as Heterogeneous Catalysts

Biomimetic Mesoporous Cobalt Ferrite/Carbon Nanoflake Helices for Freestanding Lithium‐Ion Battery Anodes

Homeotropic Concentric Helix Orientations in Chiral Nematic Cellulose Nanocrystal Films by Local Magnetic Fields

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