Simultaneous Detection of Hydroquinone, Catechol and Resorcinol by an Electrochemical Sensor Based on Ammoniated-Phosphate Buffer Solution Activated Glassy Carbon Electrode

Facile design of FeCu metal-organic frameworks anchored on layer Ti3C2Tx MXene for high-performance electrochemical sensing of resorcinol

This work reports the rational design of a composite material by growing FeCu-MOF-919 on the surface of layered Ti3C2Tx MXene. The introduction of Ti3C2Tx MXene simultaneously weakens the aggregation of FeCu-MOF-919 and Ti3C2Tx MXene, which increases the electrochemical reaction active site of the composite material and improves the electrochemical activity. Interestingly, the FeCu-MOF-919/Ti3C2Tx based sensors were used to detect resorcinol (RS) with a wide linear range (0.5-152.5 μM), excellent sensitivity (0.23 μA μM-1 cm-2), low limit of detection (LOD = 0.08 μM) and outstanding stability. Meanwhile, the sensor shows high repeatability of 1.07 % RSD, reproducibility of 1.47 % RSD and anti-interference performance. What's more, the sensor can be successfully used to detect RS in tap water with good recoveries (96.25-103.37 %, RSD ≤2.18 %), demonstrating that the FeCu-MOF-919/Ti3C2Tx exhibits significant potential as an advanced sensing apparatus for the surveillance of RS in the natural environment.

Electrochemical Detection of Dihydroxybenzene Isomers at a Pencil Graphite Based Electrode

In this work, an HB pencil electrode (HBPE) was electrochemically modified by amino acids (AAs) glycine (GLY) and aspartic acid (ASA) and designated as GLY-HB and ASA-HB electrodes. They were used in the detection of dihydroxybenzene isomers (DHBIs) such as hydroquinone (HQ), catechol (CC), and resorcinol (RS), by cyclic voltammetry (CV), and by differential pulse voltammetry. HBPE was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. These three electrodes showed a linear relationship of current with concentration of DHBIs, and the electrochemical processes were diffusion controlled in all cases. In simultaneous detection, the limit of detection, based on signal-to-noise ratio (S/N = 3), for HQ, CC, and RS was 12.473, 16.132, and 25.25 μM, respectively, at bare HBPE; 5.498, 7.119, and 14.794 μM, respectively, at GLY-HB; and 22.459, 25.478, and 38.303 μM, respectively, at ASA-HB. The sensitivity for HQ, CC, and RS was 470.481, 363.781, and 232.416 μA/mM/cm², respectively, at bare HBPE; 364.785, 282.712, and 135.560 μA/mM/cm², respectively, at GLY-HB; and 374.483, 330.108, and 219.574, respectively, at ASA-HB. The interference studies clarified the suitability and reliability of the electrodes for the detection of HQ, CC, and RS in an environmental system. Real sample analysis was done using tap water, and the proposed electrodes expressed recovery with high reproducibility. Meanwhile, these three electrodes have excellent sensitivity and selectivity, which can be used as a promising technique for the detection of DHBIs simultaneously.

Specific sensing of resorcin based on the hierarchical porous nanoprobes constructed by cuttlefish-derived biomaterials through differential pulse voltammetry

The specific detection of resorcin from its isomers is a current research hotspot. Thus in our work, a ternary hierarchical porous nanoprobe has been constructed based on the combination of cuttlefish ink and bimetallic Au@Ag nanoclusters for the specific sensing of resorcin. Briefly, through electrostatic interaction, Au@Ag core-shell nanoclusters are immobilized on the surface of polydopamine extracted from cuttlefish, which is turned into nitrogen-doped porous carbon functionalized by bimetallic Au@Ag by topological transformation subsequently. Afterward, an electrochemical sensor is fabricated based on the nanoprobes for specifically determining resorcin in solution by differential pulse voltammetry, and the linear detection ranges of the sensor are 1-100 μM and 1.2-4 mM while the detection limit reaches 0.06 μM. Meanwhile, the sensing mechanism of resorcin by the pre-fabricated sensor is detailedly studied by density functional theory to obtain a clear electrochemical process. Besides, the selectivity, stability, plus reproducibility of the pre-fabricated sensor have been also tested, and the determinations for resorcin in real environmental water samples have also been performed with good recoveries, revealing the auspicious application potential in the environmental monitoring.

Coomassie brilliant blue G 250 modified carbon paste electrode sensor for the voltammetric detection of dihydroxybenzene isomers

In this present study, coomassie brilliant blue G-250 (CBBG) modified electrode was fabricated for the specific and simultaneous detection of three dihydroxybenzene isomers such as resorcinol (RS), catechol (CC) and hydroquinone (HQ). The fabrication of the modified electrode was carried out by electrochemical polymerization of CBBG on the surface of unmodified electrode. The surface structures of bare and fabricated electrode were studied by scanning electron microscope (SEM). The established electrode portrays the very fine interface with these isomers and displayed the sufficient sensitivity and selectivity. The specific parameters of pH solution, scan rate and varying the concentration of analytes were optimized at the modified electrode. The sensor process was originated to be adsorption-controlled activity and the low limit of detection (LOD) for RS and CC was attained at 0.24 and 0.21 µM respectively. In the simultaneous study, designed sensor clearly implies the three well separated anodic peaks for RS, HQ and CC nevertheless in unmodified electrode it failed. Also, the constructed electrode was applied for the real sample analysis in tap water and obtained results are agreeable and it consistent in-between 92.80–99.48%.

An efficient electrochemical sensing of hazardous catechol and hydroquinone at direct green 6 decorated carbon paste electrode

In this proposed work, direct green 6 (DG6) decorated carbon paste electrode (CPE) was fabricated for the efficient simultaneous and individual sensing of catechol (CA) and hydroquinone (HY). Electrochemical deeds of the CA and HY were carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at poly-DG6-modfied carbon paste electrode (Po-DG6-MCPE). Using scanning electron microscopy (SEM) studied the surface property of unmodified CPE (UCPE) and Po-DG6-MCPE. The decorated sensor displayed admirable electrocatalytic performance with fine stability, reproducibility, selectivity, low limit of detection (LLOD) for HY (0.11 μM) and CC (0.09 μM) and sensor process was originated to be adsorption-controlled phenomena. The Po-DG6-MCPE sensor exhibits well separated two peaks for HY and CA in CV and DPV analysis with potential difference of 0.098 V. Subsequently, the sensor was practically applied for the analysis in tap water and it consistent in-between for CA 93.25–100.16% and for HY 97.25–99.87% respectively.

Atomic Layer Deposition of Electrocatalytic Insulator Al2O3 on Three-Dimensional Printed Nanocarbons

The advantages of three-dimensional (3D) printing technologies, such as rapid-prototyping and the freedom to customize electrodes in any design, have elevated the benchmark of conventional electrochemical studies. Furthermore, the 3D printed electrodes conveniently accommodate other active layers for diverse applications such as energy storage, catalysis, and sensors. Nevertheless, to enhance a complex 3D structure while preserving the fine morphology, conformal deposition by atomic layer deposition (ALD) technique is a powerful solution. Herein, we present the concept of coating Al₂O₃ by ALD with different thicknesses from 20 to 120 cycles on the 3D printed nanocarbon/PLA electrodes for the electrocatalytic oxidation of catechol as an important biomarker. Overall, 80 ALD cycle Al₂O₃ achieved an optimum thickness for catechol electrocatalysis. This is resonated with the enhanced adsorption of catechol at the electrode surface and efficient electron transfer, according to the two-proton, two-electron-transfer mechanism, as well as for the passivation of surface defects of the nanocarbon electrode. This work compellingly demonstrates the prospect of 3D printed electrodes modified by a functional layer utilizing a low-temperature ALD process that can be extended to other arbitrary surfaces.