Lei HUANG,Zhi-hui YANG,LÜ-ji YAN,Sikpaam Issaka ALHASSAN,Hai-yin GANG,Ting WANG,Hai-ying WANG
2D carbon ribbon/Al 2 O 3 was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods. Batch experiments of adsorption parameters such as pH, liquid/solid ratio, adsorption kinetics, adsorption thermodynamics, and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al 2 O 3 and nitrogen-doped carbon ribbon/Al 2 O 3 . The adsorption of fluoride on carbon ribbon/Al 2 O 3 could be described as the chemical and multilayer adsorption, while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al 2 O 3 followed the chemical and monolayer adsorption phenomenon. The fluoride on nitrogen-doped carbon ribbon/Al 2 O 3 had a much faster adsorption rate of 3.1×10 −7 m/s than carbon ribbon/Al 2 O 3 , which was 1.2×10 −7 m/s. The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride. Also, the diacetylene linkages (—C≡C—) and pyridinic-N were studied to understand their influences on removing fluoride. The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.
Wan Wang,Hua Bai,Haiyu Li,Qing Lv,Qing Zhang,Ning Bao
Fabrication of disposable gold working electrodes in bulk is desirable for their extensive application in electrochemical detection . In this paper the gold film electrodes were prepared by sputtering the gold film with the thickness of ∼12 nm on the double sided conductive carbon tape. The gold film coated carbon tape could be used like stickers with small square pieces and attached on ITO glass for fabrication of disposable gold film electrodes. The electrochemical responses of the gold film modified electrodes on Cr(VI) in acidic solutions were similar to previous gold electrodes, suggesting the similar mechanism as before. Cr(VI) could be determined by the amperometric method with the detection limit of 0.7 μg L −1 (0.013 μM), which was significantly improved compared with previously reported disposable gold-based electrodes. The batch-by-batch (n = 20) reproducibility of the fabricated electrodes was 7.3% at 50 μg L −1 and 3.8% at 5.0 mg L −1 , respectively. The disposable electrodes could be applied to quantify Cr(VI) in real samples including plastics, tap water and lake water with results in agreement with those obtained with HPLC-ICP-MS. This study provides a simple and effective alternative for preparation of disposable gold film electrodes.
Graphical Composite nanostructured cathode : FeOOH nanocubes with a core–shell structure and anchored on carbon ribbons have been prepared. The carbon ribbons improve the conductivity of the system and make more of the FeOOH surface available for electrochemical reaction. An Li/O 2 battery with FeOOH as the cathode material shows a specific capacity of 14816 mAh g −1 cathode and a long-term stability of 67 cycles over 400 h (see figure). A composite of FeOOH nanocubes anchored on carbon ribbons has been synthesized and used as a cathode material for Li/O 2 batteries. Fe 2+ ion-exchanged resin serves as a precursor for both FeOOH nanocubes and carbon ribbons, which are formed simultaneously. The as-prepared FeOOH cubes are proposed to have a core–shell structure, with FeOOH as the shell and Prussian blue as the core, based on information from XPS, TEM, and EDS mapping. As a cathode material for Li/O 2 batteries, FeOOH delivers a specific capacity of 14816 mA h g −1 cathode with a cycling stability of 67 cycles over 400 h. The high performance is related to the low overpotential of the oxygen reduction/evolution reaction on FeOOH. The cube structure, the supporting carbon ribbons, and the -OOH moieties all contribute to the low overpotential. The discharge product Li 2 O 2 can be efficiently decomposed in the FeOOH cathode after a charging process, leading to higher cycling stability. Its high activity and stability make FeOOH a good candidate for use in non-aqueous Li/O 2 batteries.
The template-controlled electrodeposition has been widely used for fabricating arrayed micro-/nanostructures (both metallic and composite), which typically requires the vacuum-deposition of a conductive metal film on the template and faces the challenge of detaching them from the substrate electrode for subsequent characterization/application. Herein we report that such a template-assisted fabrication strategy can be readily accomplished by using double-sided carbon tapes in conjunction with nanoporous templates of choice, which allows for not only simple, rapid assembly with any substrate electrode for the deposition of arrayed micro-/nanostructures with standard electrochemical equipment, but also their effort-less detachment for subsequent characterization and application. As of the proof-of-concept, we have demonstrated that “hemisphere” gold ultramicroelectrode arrays with characteristic redox responses can be reproducibly prepared in a few minutes with appropriate deposition time and potential. The application of this convenient method as a routine, benchtop protocol for preparing different types of arrayed micro-/nanostructures (e.g., Au, Cu, and Pt) using various nanoporous templates (both polycarbonate membranes and anodic aluminum oxide substrates) via conventional electrochemical deposition has been also described.
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