A glassy carbon electrode modified with carbon nano-fragments and bismuth oxide for electrochemical analysis of trace catechol in the presence of high concentrations of hydroquinone

CuS nanoparticles decorated MoS2 sheets as an efficient nanozyme for selective detection and photocatalytic degradation of hydroquinone in water

Cost effective and efficient CuS–MoS₂ nanocomposite with enhanced peroxidase enzyme mimetics and photocatalytic activity was synthesized by simple hydrothermal method and successfully utilized for sensing and detection of toxic hydroquinone molecules in aqueous medium.

Simultaneous determination of dihydroxybenzene isomers using a three-dimensional over-oxidized polypyrrole–reduced graphene oxide composite film electrode prepared by an electrochemical method

A 3D-over-oxidized polypyrrole–reduced graphene oxide composite film was prepared by an electrochemical procedure, which showed high electrochemical activity and good selectivity for simultaneous determination of dihydroxybenzene isomers.

A voltammetric sensor for simultaneous determination of hydroquinone and catechol by using a heterojunction prepared from gold nanoparticle and graphitic carbon nitride

An electrochemical sensor is described for the simultaneous determination of hydroquinone (HQ) and catechol (CC) based on a nanocomposite consisting of gold nanoparticles and graphitic carbon nitride (g-C₃N₄). The nanocomposite was synthesized via one-step thermal polymerization route and characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared techniques. The results confirmed the close contact between gold nanoparticles and g-C₃N₄. The nanocomposites exhibited the enhanced electrocatalytic redox towards HQ and CC. A glassy carbon electrode was modified with the nanocomposite to obtain a sensor that exhibited favorable analytical properties in the simultaneous detection of HQ and CC, with voltammetric peaks typically near -0.14 and - 0.02 V (vs. saturated calomel electrode). Linear responses are found between 1.0 and 320 μM for HQ (with a 0.3 μM detection limit; at S/N = 3), and between 0.1 and 320 μM for CC (with a 0.04 μM detection limit; at S/N = 3). The sensor was applied for the simultaneous determination of HQ and CC in spiked water samples, and acceptable recoveries were achieved. The superior sensing properties of the electrode are attributed to the synergy between the microstructure (heterojunction and porosity) and the π interactions between phenolic isomers and g-C₃N₄. Graphical abstractA novel electrochemical sensor is demonstrated for the simultaneous determination of hydroquinone and catechol based on a nanocomposite consisting of gold nanoparticles (AuNPs) and graphitic carbon nitride (g-C₃N₄).

3D-Flower-Like Copper Sulfide Nanoflake-Decorated Carbon Nanofragments-Modified Glassy Carbon Electrodes for Simultaneous Electrocatalytic Sensing of Co-existing Hydroquinone and Catechol

A copper sulfide nanoflakes-decorated carbon nanofragments-modified glassy carbon electrode (CuS-CNF/GCE) was fabricated for the electrocatalytic differentiation and determination of hydroquinone (HQ) and catechol (CC). The physicochemical properties of the CuS-CNF were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The electrocatalytic determination of HQ and CC over the CuS-CNF/GCE was evaluated by cyclic voltammetry and differential pulse voltammetry. An excellent detection limit and sensitivity of the CuS-CNF/GCE are obtained (0.293 µM and 0.259 µM) with a sensitivity of 184 nA µM⁻¹ cm⁻² and 208 nA µM⁻¹ cm⁻² (S/N=3) for HQ and CC, respectively. In addition, the CuS-CNF/GCE shows a selective identification of HQ and CC over potential interfering metal ions (Zn²⁺, Na⁺, K⁺, NO³⁻, SO₄²⁻, Cl⁻) and organic compounds (ascorbic acid, glucose), and a satisfactory recovery is also obtained in the spiked water samples. These results suggest that the CuS-CNF/GCE can be used as an efficient electrochemical sensor for the simultaneous determination of co-existing environmental pollutants such as HQ and CC in water environments with high selectivity and acceptable reproducibility.

Sensitive electrochemical detection of gp120 based on the combination of NBD-556 and gp120

As is known, the employment of molecular imprinting polymer (MIP) as specific sensing materials in sensors, namely MIP-based sensors. In this contribution, we devised a MIP electrochemical sensor for the detection of variable-format conformations protein gp120. The sensor was constructed by using a grapheme-like carbon nanfragment (CNF) and bismuth oxides composites (CNF-Bi) as decoration material, small-molecule entry inhibitor NBD-556 and gp120 conjugates NBD-556@gp120 instead of gp120 as the template, and pyrrole as an electropolymerization monomer. Cyclic voltammetry, differential pulse voltammetry, scanning electron microscopy and transmission electron microscope were used to characterize the preparation process of the sensor. Results showing that, under optimized conditions, the introduction of NBD-556 make the specific recognition and analytical properties of the MIP sensor towards gp120 more efficient. The response currents were proportional to the NBD-556@gp120 concentrations in the range of 0.0002 ng mL^-1 to 200 ng mL^-1 with the detection limit of 0.0003 ng mL^-1 based on S/N = 3. Meanwhile, the NBD-556@gp120 based MIP sensor also shows acceptable stability and reproducibility. When used for the detection of gp120 in human plasma, it also showed good accuracy. This research idea is in great promising for the early diagnosis of HIV-1 virus and can also be extended to the detection of other conformationally unstable proteins.

Amperometric determination of hydroquinone and catechol using a glassy carbon electrode modified with a porous carbon material doped with an iron species

A porous carbon material doped with an iron species (Fe/PC) was prepared by carbonizing a mixture of zeolitic imidazolate framework-8 in the presence of iron(II) ions. The resulting material was characterized by X-ray diffraction, nitrogen adsorption isotherms, transmission electron microscopy, and by Raman and X-ray photoelectron spectroscopy. Fe/PC was the deposited on the surface of glassy carbon electrode (GCE) to obtain a sensor for amperometric determination of phenolic compounds. The unique catalytic activity, good electrical conductivity and hierarchical structure of the Fe/PC composite results in good electrooxidative activity towards hydroquinone (HQ; typically at 44 mV) and catechol (CC; typically at 160 mV). Under optimal conditions, the amperometric responses are linear in the range from 0.1 to 120 μmol · L^-1 for HQ, and from 1.0 to 120 μmol · L^-1 for CC. The respective detection limits are 14 and 33 nmol · L^-1. The sensor is highly selective against potential interferents and was successfully applied to the determination of HQ and CC contents in (spiked) water samples. Graphical abstract An amperometric sensor for phenolic compounds was constructed by using a metal-organic framework derived iron doped porous carbon material.

Synthesis and application of bismuth ferrite nanosheets supported functionalized carbon nanofiber for enhanced electrochemical detection of toxic organic compound in water samples

Recently, the multiferroic material has fabulous attention in numerous applications owing to its excellent electronic conductivity, unique mechanical property, and higher electrocatalytic activity, etc. In this paper, we reported that the synthesis of bismuth ferrite (BiFeO₃) nanosheets integrated functionalized carbon nanofiber (BiFeO₃ NS/F-CNF) nanocomposite using a simple hydrothermal technique. Herein, the structural changes and crystalline property of prepared BiFeO₃ NS/F-CNF nanocomposite were characterized using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). From this detailed structural evolution, the formation of nanosheets like BiFeO₃ and its nanocomposite with F-CNF were scrutinized and reported. Furthermore, the as-prepared BiFeO₃ NS/F-CNF nanocomposite modified glassy carbon electrode (GCE) was applied for electrochemical detection of catechol (CC). As expected, BiFeO₃ NS/F-CNF/GCE shows excellent electrocatalytic activity as well as 3.44 (F-CNF/GCE) and 7.92 (BiFeO₃ NS/GCE) fold higher electrochemical redox response for CC sensing. Moreover, the proposed sensor displays a wide linear range from 0.003 to 78.02 µM with a very low detection limit of 0.0015 µM. In addition, we have validated the real-time application of our developed CC sensor in different water samples.