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Rationally exfoliating chitin into 2D hierarchical porous carbon nanosheets for high-rate energy storage
Nano Research 2020, 13 (6): 1604-1613
Published: 14 May 2020
Downloads:36

Two-dimensional (2D) carbon nanomaterials with hierarchical porous structure and heteroatoms doping are highly desirable in the fields of energy storage because of their rich active surface and open ion diffusion channels. However, the scalable preparation of carbon materials simultaneously possessing ultrathin 2D feature and hierarchical pores remains a considerable challenge. Herein, a facile one-step method to massively fabricate 2D porous chitin nanosheets (coded as PCNs) via a phytic acid assisted top-down exfoliation of bulk chitin under hydrothermal treatment was presented. Subsequently, 2D carbon nanosheets with extra-thin thickness (3.6 nm), well-defined hierarchical porosity, high specific surface area (855 m2·g-1), as well as abundant self-doped heteroatoms (N, O, P) were fabricated by carbonizing the PCNs, and was named as HPCNs. The as-obtained HPCNs demonstrated remarkable electrochemical performance as electrode material for supercapacitors. The symmetric supercapacitors (SSCs) based on HPCNs exhibited a high specific capacitance of 79 F·g-1 (316 F·g-1 for single electrode) in 6 M KOH aqueous electrolyte solution, as well as a remarkable energy density of 23.8 W·h·kg-1 by using 1 M Li2SO4 as electrolyte. It is also demonstrated that HPCNs/PCNs hybrid dispersions can be used as inks to fabricate conductive films and energy devices with high strength and superior flexibility. This work paves a new avenue for the economical and large-scale synthesis of 2D hierarchically porous carbon materials for energy storage related applications.

Research Article Issue
Ultra-small Pd clusters supported by chitin nanowires as highly efficient catalysts
Nano Research 2018, 11 (6): 3145-3153
Published: 22 May 2018
Downloads:53

For the first time, chitin microspheres woven from nanowires with multi-scale porous structures were used as an excellent support for a catalyst of ultra-small Pd clusters. The Pd species anchored on the precursor Pre-Pd@chitin were 0.6 nm in average size, while the reduced catalyst Red-Pd@chitin featured ultra-small particles of 1.3 nm in average size. X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) demonstrated that the Pd catalyst in both oxidative and reductive states retained good dispersity and ultra-small clusters. The catalyst was tested for the hydrogenation of p-nitroanisole, exhibiting an excellent initial rate (13× that of commercial Pd/C)and excellent turnover frequency reaching 52, 000 h-1. Furthermore, the catalyst could be recycled and used more than 10 times with no decay of the catalytic activity, suggesting potential industrial applications.

Research Article Issue
Construction of highly stable selenium nanoparticles embedded in hollow nanofibers of polysaccharide and their antitumor activities
Nano Research 2017, 10 (11): 3775-3789
Published: 27 May 2017
Downloads:13

Nanotechnologies have been exploited to develop safe and effective medicines and pharmaceuticals. In the present study, a novel functional nanomedicine constructed from a bioactive polysaccharide and selenium nanoparticles (SeNPs) was developed. A highly-branched β-(1→3)-D-glucan (AF1) with high anti-tumor activity was used to self-assemble hollow nanofibers with an apparent average diameter of 92 nm; Se nanoparticles were synthesized via the reduction of sodium selenite. The results of light scattering, transmission electron microscopy, and X-ray diffraction demonstrated that the spherical SeNPs with a mean diameter of 46 nm were entrapped in the cavities of the AF1 hollow nanofibers through the formation of Se–O bonds between SeNPs and AF1, leading to the good dispersion and high stability in water for over 16 months. In vitro and in vivo assays indicated that the AF1-Se nanocomposite had higher anti-tumor activities against breast cancer. Furthermore, AF1-Se displayed a broad-spectrum inhibition against human cancers with low half maximal inhibitory concentration (IC50) values and low toxicity to normal cells. Particularly, the inhibition ratio of AF1-Se against MCF-7 cancer cells reached 75% at a concentration of 200 μg·mL–1 with 29 μM Se content, much higher than that by treatment with AF1 alone, suggesting a strong synergic effect and nano impact. Overall, we developed a method for increasing the stability, anti-tumor activity, and safety of SeNPs by wrapping with bioactive polysaccharides.

Research Article Issue
Construction of controllable size silver nanoparticles immobilized on nanofibers of chitin microspheres via green pathway
Nano Research 2016, 9 (7): 2149-2161
Published: 24 May 2016
Downloads:23

In the present work, nanofibrous chitin microsphere (NCM) was prepared via sol–gel transition from a chitin solution dissolved in a NaOH/urea aqueous system at low temperatures. Ag nanoparticles (AgNPs) were synthesized via an in situ reduction of silver nitrate using trisodium citrate dehydrate and were immobilized on chitin nanofibers to obtain composite microspheres that consist of nanofibers and AgNPs (NCM-Ag). The size of AgNPs could be controlled in the range of 10 to 70 nm, depending on the concentration of AgNO3. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analyses showed that the chitin nanofibers have a strong affinity toward AgNPs, resulting from the interaction between the acetamino group of chitin and the AgNPs. The NCM-Ag exhibited a perfect nanoporous structure and high surface area, as well as high stability in organic solvents. Moreover, in the catalytic epoxidation of olefin (particularly, the conversion of styrene to styrene epoxide), NCM-Ag exhibited an excellent selectivity of up to 90%. Converting chitin powder into chitin microspheres using an environmentally friendly technique is a green process, which is beneficial for the large-scale synthesis of industrial products. More importantly, this work provides a green synthetic pathway for the construction of size-controlled noble metal nanoparticles immobilized on nanofiber support, which have a wide range of potential applications.

Research Article Issue
Facile construction of carbon dots via acid catalytic hydrothermal method and their application for target imaging of cancer cells
Nano Research 2016, 9 (1): 214-223
Published: 20 January 2016
Downloads:32

To solve the problem of high temperature or long reaction time in hydrothermal synthesis of carbon dots (CDs), a novel method based on the promoting carbonization by hydrochloric acid as catalysis was developed in present work. The acid catalyzed carbon dots (ACDs) were prepared facilely from tryptophan and phenylalanine at 200 ℃ for 2 h. In our findings, the acids could promote significantly the formation of the ACDs' carbon core, as a result of the accelerating of the carbonization due to the easy deoxidation. The ACDs showed an average size of 4.8 nm, and consisted of high carbon crystalline core and various surface groups. The ACDs exhibited good optical properties and pH-dependent photoluminescence (PL) intensities. Furthermore, the ACDs were safe and biocompatible. The experimental results demonstrated that such new ACDs were connected with DNA-aptamer by EDC/NHS reaction maintaining both the bright fluorescence and recognizing ability on the cancer cells, which so could be served as an effective PL sensing platform. The resultant DNA-aptamer with ACDs (DNA-ACDs) could stick to human breast cancer cells (MCF-7) specifically, and exhibited high sensitivity and selectivity, indicating the potential applications in the cancer cells targeted imaging fields.

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