Three dimensional hybrid carbon materials have been prepared using different biomass-derived porous carbons as catalyst supports for growing multi-walled carbon nanotubes (MWCNTs) via a chemical ...vapor deposition method. The nickel catalyst-loaded supports before and after growing MWCNTs were characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy spectra, and mercury porosimetry. The results show that the grown MWCNTs microstructures are closely related to the porous structures and surface conditions of the carbon supports. By using bamboo as template, a porous carbon support with a large total pore volume, appropriate pore size, and abundant favorable surface functional groups is obtained, which is found to be an ideal support for growing the MWCNTs. Investigation of growth mechanism demonstrated that the combination of appropriate porous structures and surface conditions plays an essential role in catalyst distribution and MWCNTs growth.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Through a simple room-temperature photoreduction process, this letter conformally replicates 3D submicrometer structures of wing scales from two butterfly species into Ag to generate practical ...surface-enhanced Raman scattering (SERS) substrates. The Ag replicas of butterfly scales with higher structural periodicity are able to detect rhodamine 6G at a low concentration down to 10–9 M, which is three orders of magnitude lower than the detectable concentration limit of using quasi-periodic Ag butterfly structures. This result presents a way to select suitable scale morphologies from 174 500 species of Lepidopterans to replicate, as consumable SERS substrates with low cost and high reproducibility.
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IJS, KILJ, NUK, PNG, UL, UM
Graphene oxide is extensively compounded with polymers toward a wide variety of applications. Less studied are few‐layer or multi‐layer highly crystalline graphene, both of which are herein named as ...graphene platelets. This article aims to provide the most recent advancements of graphene platelets and their polymer composites. A first focus lies on cost‐effective fabrication strategies of graphene platelets – intercalation and exfoliation – which work in a relative mass scale, e.g., 5.3 g h−1. As no heavy oxidization is involved, the platelets have high crystalline integrity, e.g., C:O ratio over 8.0, with thicknesses 2–4 nm and lateral dimension up to a few micrometers. Through carefully selecting the solvent for dispersion and the molecules for surface modification, graphene platelets can be liquid‐processable, enabling them to be printed, coated, or compounded with various polymers. A purpose‐designed experiment is undertaken to unravel the effect of reasonable ultrasonication time on the platelet thickness. Typical polymer/graphene platelet composites are critically examined for their preparation, structure, and applications such as thermal management and flexible/stretchable electronic devices. Perspectives on the limitations, current challenges, and future prospects for graphene platelets and their polymer composites are provided.
Graphene platelets referring to few‐layer or multi‐layer highly crystalline graphene have attracted increasing attention for the development of polymer composites. This article reviews the recent platelet fabrication strategies – intercalation and exfoliation from graphite. The platelets processable in liquid can be printed, coated, or compounded with various polymers to fabricate various functional composites and devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A novel method for duplicating the hierarchical structures of biological substances at nanometer resolution in manganese oxides has been developed. This innovation uses natural biomorphic specimens, ...such as butterfly wing, cotton, and wood as templates. The biotemplates were first treated with either HCl/NaOH or HCl/H2O2/NaOH and then mixed with an aqueous solution of KMnO4. The treated biological materials were then ultrasonically irradiated, and finally, the biological templates were removed by calcination in air at temperatures between 500 and 800 °C. The structures of the resulting manganese oxides were characterized by a combination of XRD, FE-SEM, TEM and EDS. It was found that the fine hierarchical structures of the biological templates down to the nanometer scale were faithfully duplicated, and the duplication was positive. A mechanism for the positive replication is proposed and discussed in terms of the effects of the sonochemical reaction as well as the surface modification prior to the sonochemical reaction. The same sonochemical method can be extended to the duplication of intricate hierarchical structures of other biological forms in a large range of metal oxides.
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IJS, KILJ, NUK, PNG, UL, UM
Multilayers containing a perylene diimide labelled star polymers (FSP) donor adjacent to phosphorus dendrimer layer on a silver substrate were constructed by layer by layer (LBL) approach. Using ...Surface Plasmon Enhanced Fluorescence Spectroscopy (SPFS) technique, a time‐resolved ultrasensitive and selective detection of DNA targets relying on enhanced optical fields associated with energy transfer (ET) were achieved under the excitation at 543 nm. The detection limit is about 8 orders of magnitude better than the achieved one under the excitation at 632 nm, which is ascribed to no energy transfer from the donor to the acceptor under the excitation at 632 nm, resulting in much weak detection signal in turn.
Schematic demonstration of the detection of DNA hybridization on a silver surface deposited with multilayer containing a fluorescent star polymer (FSP) donor layer and a phosphorous dendrimer layer by layer‐by‐layer (LBL) approach, the enhanced optical fields associated with energy transfer (ET) from FSP donors to dye labelled DNA targets in surface plasmon field enhanced fluorescence spectroscopy (SPFS).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Layered crystals, once exfoliated in liquids, create nanosheets with large surface area and likely generate electron band gaps. The current liquid exfoliation of graphite is performed by either ...oxidation, ultrasonication or the oxidation followed by ultrasonication; these methods are respectable but have limitations in general: the oxidation actually produces graphene oxide while the sonication is time-consuming with a low yield. In this paper we report a highly effective yet simple approach for the fabrication of high-quality graphene; the approach consists of simultaneously oxidizing and ultrasonicating graphite for merely 60 min, followed by washing and filtration. Exfoliation was markedly promoted by the simultaneous treatment, where 80% of the sheets comprise single or few layers with lateral dimensions ranging 50 nm to over 100 nm; their carbon to oxygen ratio is at 8.85; the ratio of Raman D- to G-band intensity is as low as 0.211; and the sheets can be stably dispersed in acetone for at least 48 hours and they have an electrical conductivity over 600 S cm
−1
. A thin graphene film made by casting exhibited a sheet resistance of ∼1000 Ω square
−1
with 80% transparency at 550 nm.
The convenience of injectable hydrogels that can provide high loading of diverse phototherapy agents and further long‐time retention at the tumor site has attracted tremendous interest in ...simultaneous photothermal and photodynamic cancer therapies. However, to incorporate the phototherapy agents into hydrogels, complex modifications are generally unavoidable. Moreover, these phototherapy agents usually suffer from low efficiency and work at different irradiation wavelengths outside the near infrared windows. Hence, a method for the fabrication of an injectable hydrogel for simultaneous photothermal therapy and photodynamic therapy, through the Schiff‐base reaction between amido modified carbon dots (NCDs) and aldehyde modified cellulose nanocrystals is proposed. The NCDs act as both phototherapy agents and crosslinkers to form hydrogels. Significantly, the NCDs demonstrate an extremely high photothermal conversion efficiency of 77.6% which is among the highest levels for photothermal agents and a high singlet quantum yield of 0.37 under a single 660 nm light‐emitting diode irradiation. The hydrogels are examined through in vitro and in vivo animal experiments which show nontoxic and effectively tumor inhibition. Thus, the strategy of direct reaction of phototherapy agents and the matrix not only provides new strategies for injectable hydrogel fabrication but paves a new road for advanced tumor treatment.
A novel strategy is developed for the fabrication of injectable hydrogels with extremely high efficiency in simultaneous photothermal therapy and photodynamic therapy, through a simple Schiff base reaction between carbon dots decorated with amido groups and aldehyde modified cellulose nanocrystals, which not only provides a new strategy for injectable hydrogel fabrication but paves a new road for advanced tumor treatment.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Inspired by the high light-harvesting properties of typical butterfly wings, ceramic WO
3
butterfly wings with hierarchical structures of bio-butterfly wings was fabricated using a template of
...PapilioParis
butterfly wings through a sol–gel method. The effect of calcination temperatures on the structures of the ceramic butterfly wings was investigated and the results showed that the WO
3
butterfly wing replica calcined at 550 °C (WO
3
replica-550) is a single phase and has a high crystallinity and relatively fine hierarchical structure. The average grain size of WO
3
replica-550 and WO
3
powder are around 32.6 and 42.2 nm, respectively. Compared with pure WO
3
powder, WO
3
replica-550 demonstrated a higher light-harvesting capability in the region from 460 to 700 nm and more importantly the higher charge separation rate, as evidenced by electron paramagnetic resonance measurements. Photocatalytic O
2
evolutions from water were investigated on the ceramic butterfly wings and pure WO
3
powder under visible light (
λ
> 420 nm). The results showed that the amount of O
2
produced from WO
3
replica-550 is 50 % higher than that of the pure WO
3
powder. The improved photocatalytic performance of WO
3
replica-550 is attributed to the quasi-honeycomb structure inherited from the
PapilioParis
butterfly wings, providing both high light-harvesting efficiency and efficient charge transport through the WO
3
.
•A novel nonenzymatic glucose sensor based on the Ag-CuO/rGO composite.•Ag-CuO with average particle size of 10 nm was dispersed on the surface of rGO.•The sensor exhibits a wide linear range, high ...sensitivity and low detection limit.
In this study, a nano Ag-CuO/rGO (reduced graphene oxide) composite was designed and constructed as a novel nonenzymatic glucose sensor. The composite was fabricated through a one-step synthesis process. In the process, Ag-CuO with an average particle size of 10 nm formed and dispersed homogeneously on the surface of rGO sheets. When used for nonenzymatic glucose sensing, the resultant Ag-CuO/rGO composite showed a high sensitivity of 214.37 μA mM−1 cm−2 and an extremely wide linear response from 0.01 to 28 mM with a 0.76 μM detection limit (S/N = 3) at +0.6 V. The excellent sensing properties of the composite are probably due to the synergistic effect of the combination of Ag, CuO nanoparticles and rGO. The electron transfer is improved by the addition of Ag nanoparticles, and the composite electrode possesses larger surface area due to the rGO. The Ag-CuO/rGO composite doe not only show the good catalytic activity, excellent selectivity but also outstanding long term stability, good reproducibility, which makes it a novel type of composite for nonenzymatic glucose sensing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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