Aromatic heterocyclic microporous polymers with high surface areas are obtained by directly crosslinking of the heterocyclic monomers under mild conditions. Owing to the narrow pore system and the ...heteroatom‐rich pore surface, these networks exhibit high CO2 adsorption capacity and selectivity. At 273 K, the CO2/N2 selectivity of Py‐1 is about 117, which is among the highest the reported microporous materials.
To explore electrochemistry of the composites of ZnO and reduced graphene oxides (rGO), graphene oxide (GO) was in-situ reduced with Zn powders. The morphology and micro-structure of synthesized ...ZnO@rGO composites were characterized using scanning electron microscopy, transmission electron microscopy, and atomic force microscope. Energy dispersive spectroscopy, X-ray diffraction, Raman, and Fourier Transform infrared spectroscopy were employed to clarify the chemical composition of ZnO@rGO composites. Electrochemical properties of ZnO@rGO composites were studied using cyclic voltammetry and impedance, revealing a large surface area and many active sites. Accordingly, electrochemical sensing of a neutral organic dye Sudan I and a charged metal ion Pb2+ was achieved on ZnO@rGO composites. The strategy of in-situ reduction of GO with Zn powders thus owns great application prospects in constructing a universal and sensitive electrochemical sensing platform.
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The simultaneous determination of xanthine (XA) and hypoxanthine (HXA) has been proved to be a feasible approach for the assessment of fish freshness. In this study, copper(II) nitrate and ...1,3,5-benzenetricarboxylic acid (H3BTC) were used as precursors to prepare various Cu-BTC frameworks with the addition of various amounts of triethylamine at room temperature. The characterization of X-ray diffraction, Fourier-transform infrared spectroscopy and Raman spectroscopy testified that the obtained materials are Cu-BTC frameworks. However, the amount of triethylamine had significant effects on the morphology, active response area and electron transfer ability of Cu-BTC frameworks. The oxidation behavior of XA and HXA demonstrated that the prepared Cu-BTC frameworks exhibited higher sensing activity, with greatly-enhanced oxidation signals. More importantly, the amount of triethylamine obviously affected the accumulation capacity and signal enhancement ability of Cu-BTCs toward XA and HXA, as confirmed from double potential step chronocoulometry. Based on the triethylamine-tuned signal amplification strategy of Cu-BTC frameworks, a highly-sensitive and simple electrochemical sensing system was developed for the assessment of fish freshness by simultaneous detection of XA and HXA. The developed sensing method was used in practical samples, and the results were validated by high-performance liquid chromatography.
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•A strategy for regulating morphology and sensing performance of Cu-BTC frameworks.•Morphology-dependent electrochemical signal amplification strategy for XA and HXA.•Highly-sensitive and convenient sensing system for evaluation of fish freshness.
In this work, large size (i.e., diameter > 100 nm) graphene tubes with nitrogen‐doping are prepared through a high‐temperature graphitization process of dicyandiamide (DCDA) and Iron(II) acetate ...templated by a novel metal–organic framework (MIL‐100(Fe)). The nitrogen‐doped graphene tube (N‐GT)‐rich iron‐nitrogen‐carbon (Fe‐N‐C) catalysts exhibit inherently high activity towards the oxygen reduction reaction (ORR) in more challenging acidic media. Furthermore, aiming to improve the activity and stability of conventional Pt catalysts, the ORR active N‐GT is used as a matrix to disperse Pt nanoparticles in order to build a unique hybrid Pt cathode catalyst. This is the first demonstration of the integration of a highly active Fe‐N‐C catalyst with Pt nanoparticles. The synthesized 20% Pt/N‐GT composite catalysts demonstrate significantly enhanced ORR activity and H2‐air fuel cell performance relative to those of 20% Pt/C, which is mainly attributed to the intrinsically active N‐GT matrix along with possible synergistic effects between the non‐precious metal active sites and the Pt nanoparticles. Unlike traditional Pt/C, the hybrid catalysts exhibit excellent stability during the accelerated durability testing, likely due to the unique highly graphitized graphene tube morphologies, capable of providing strong interaction with Pt nanoparticles and then preventing their agglomeration.
An iron‐containing metal–organic framework, MIL‐100(Fe), is employed to prepare a new oxygen‐reduction non‐precious metal catalyst containing bamboo‐like nitrogen‐doped graphene tubes (diameter > 100 nm). The highly active graphene tubes are further integrated with Pt nanoparticles in order to build a hybrid electrocatalyst, exhibiting significantly improved activity and stability compared to conventional Pt/C catalysts in acid electrolyte.
Bisphenol A (BPA) is an emerging contaminant with severe toxic effects such as disrupting endocrine system or causing cancer, therefore, developing sensitive and selective sensor for BPA is very ...important and interesting. Herein, MCM-41, a kind of mesoporous silica, was synthesized and then used to prepare an electrochemical sensor for BPA. For better comparison, carbon nanotubes, activated carbon, silica gel and graphite were also employed to prepare electrochemical sensor for BPA. The electrochemical behaviors of BPA at different electrochemical sensors were investigated. Compared with other sensors, the MCM-41 sensor greatly enhances the response signal of BPA due to the large active surface area and high accumulation efficiency. The effects of pH value, accumulation time and sensor composition were examined. The linear range is from 2.2
×
10
−7 to 8.8
×
10
−6
mol
L
−1, and the limit of detection is evaluated to be 3.8
×
10
−8
mol
L
−1. Finally, the MCM-41 sensor was successfully employed to determine BPA in water samples.
This work reported the simple and direct detection of 3,3′,5,5′‑tetrabromobisphenol A (TBBPA) by a polydopamine imprinted electrochemical sensor. The imprinted film was directly prepared by ...electropolymerization of dopamine on a glassy carbon electrode in the presence of template molecule, and then characterized using electrochemical probe of potassium ferricyanide, scanning electron microscopy and atomic force microscopy. It was found that the obtained sensing film greatly enhanced the oxidation signals of TBBPA due to strong accumulation ability. The influences of electropolymerization conditions (e.g. template concentration, scan cycles and scan rates), accumulation time and pH value were studied. The developed sensing platform exhibited good reproducibility, excellent sensitivity and selectivity, offering a low detection limit (0.27 nM) and a linear range from 1 to 50 nM. It was applied for TBBPA detection in plastic e-waste samples, and the results were consistent with those obtained by high-performance liquid chromatography.
It is quite important to monitor synthetic dyes in foods because of their potential harmfulness to human beings. Herein, alumina microfibers with porous structures were prepared via hydrothermal ...reaction, and then used to construct a highly sensitive platform for the detection of sunset yellow. In pH 6.5 phosphate buffer, an oxidation peak was observed for sunset yellow, and the oxidation peak currents of sunset yellow were greatly increased by alumina microfibers. The influences of pH value, amount of alumina microfibers and accumulation time on the signal enhancement of sunset yellow were discussed. As a result, a novel electrochemical method was developed for the detection of sunset yellow. The linear range was from 0.5 to 100nM, and the limit of detection was 0.16nM (72.4ngL−1) after 2-min accumulation. It was applied in soft drink samples, and the detected results consisted with the values that obtained by high-performance liquid chromatography.
ZnCdHgSe quantum dots (QDs) functionalized with N-acetyl-l-cysteine were synthesized and characterized. Through layer-by-layer assembling, the ZnCdHgSe QDs was integrated with a polymerized ...1-decyl-3-3-pyrrole-1-yl-propylimidazolium tetrafluoroborate (PDPIT) ionic liquid film modified indium tin oxide (ITO) electrode to fabricated a photoelectrochemical interface for the immobilization of rabbit antihuman neuron specific enolase (anti-NSE). After being treated with glutaraldehyde vapor and bovine serum albumin successively, an anti-NSE/ZnCdHgSe QDs/PDPIT/ITO sensing platform was established. Simplely using a white-light LED as an excitation source, the immunoassay of neuron specific enolase (NSE) was achieved through monitoring the photocurrent variation. The polymerized ionic liquid film was demonstrated to be an important element to enhance the photocurrent response of ZnCdHgSe QDs. The anti-NSE/ZnCdHgSe QDs/PDPIT/ITO based immunosensor presents excellent performances in neuron specific enolase determination. The photocurrent variation before and after being interacted with NSE exhibits a good linear relationship with the logarithm of its concentration (log c NSE) in the range from 1.0 pg mL–1 to 100 ng mL–1. The limit of detection of this immunosensor is able to reach 0.2 pg mL–1 (S/N = 3). The determination of NSE in clinical human sera was also demonstrated using anti-NSE/ZnCdHgSe QDs/PDPIT/ITO electrode. The results were found comparable with those obtained by using enzyme-linked immunosorbent assay method.
The monitoring of synthetic colourants in foods is very important due to their potential toxicity and pathogenicity. Herein, an electrochemical sensor for rapid and simple detection of Ponceau 4R and ...Allura Red was constructed using multi-wall carbon nanotube (MWNT) sensing film. In pH 7.0 phosphate buffer, two oxidation peaks are observed at 0.56 and 0.68
V for Ponceau 4R and Allura Red. Because of its large surface area and high accumulation efficiency, the MWNT film sensor remarkably enhances the oxidation signals of Ponceau 4R and Allura Red. The detection parameters such as pH value, amount of MWNT, accumulation potential and time were optimised. The MWNT film sensor possesses high sensitivity to Ponceau 4R and Allura Red, and the limits of detection are as low as 15 and 25
μg
L
−1. Finally, the MWNT sensor was successfully used to detect Ponceau 4R and Allura Red in different soft drinks.
A novel ionic liquid, 4-amino-1-(3-mercapto-propyl)-pyridine hexafluorophosphate (AMPPH), was successfully synthesized and characterized. Subsequently, AMPPH was used as a functional monomer to ...fabricate AMPPH-modified gold nanoparticles (AMPPH–AuNPs) via a one-pot synthesis method. The as-prepared AMPPH–AuNPs were confirmed with transmission electron microscopy and X-ray photoelectron spectroscopy. AMPPH–AuNPs were used to construct a biocompatible interface to immobilize rabbit anti-human IgG (anti-HIgG) onto a glassy carbon electrode (GCE) surface, followed by a cross-linking step with glutaraldehyde to fabricate an anti-HIgG–AMPPH–AuNPs/GCE. The nonspecific binding sites were enclosed with bovine serum albumin (BSA) to develop an immunosensor for human IgG. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical properties of the developed immunosensor. The results indicate that AMPPH–AuNPs can improve the immunosensing performance. The current response of the immunosensor was found linearly related to human IgG concentration in the range of 0.1–5.0 ng mL–1 and 5.0–100.0 ng mL–1. The detection limit is estimated to be 0.08 ng mL–1 (S/N = 3). The obtained immunosensor was successfully applied to the analysis human IgG immunoglobulin in human serum, and the results were well consistent with ELISA method.
