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A highly sensitive electrochemical sensor for the detection of ascorbic acid (AA) was first fabricated using network-like carbon nanosheets (NCN) as an enhanced electrode modifier. Novel carbon nanosheets were synthesized from willow catkin via a high temperature carbonization and chemical activation process with the aid of potassium hydroxide (KOH...
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Nanostructured piezoelectric semiconductors offer unprecedented opportunities for high‐performance sensing in numerous catalytic processes of biomedical, pharmaceutical, and agricultural interests, leveraging piezocatalysis that enhances the catalytic efficiency with the strain‐induced piezoelectric field. Here, a cost‐efficient, high‐performance piezo‐electrocatalytic sensor for detecting l‐ascorbic acid (AA), a critical chemical for many organisms, metabolic processes, and medical treatments, is designed and demonstrated. Zinc oxide (ZnO) nanorods and nanosheets are prepared to characterize and compare their efficacy for the piezo‐electrocatalysis of AA. The electrocatalytic efficacy of AA is significantly boosted by the piezoelectric polarization induced in the nanostructured semiconducting ZnO catalysts. The charge transfer between the strained ZnO nanostructures and AA is elucidated to reveal the mechanism for the related piezo‐electrocatalytic process. The low‐temperature synthesis of high‐quality ZnO nanostructures allows low‐cost, scalable production, and integration directly into wearable electrocatalytic sensors whose performance can be boosted by otherwise wasted mechanical energy from the working environment, for example, human‐generated mechanical signals. A cost‐efficient, high‐performance piezo‐electrocatalytic sensor is designed for detecting l‐ascorbic acid (AA), a critical chemical for many organisms, metabolic processes, and medical treatments. The electrocatalytic efficacy of AA is significantly boosted by the piezoelectric polarization induced in the nanostructured semiconducting zinc oxide catalysts.
In this article, an electrochemical sensor was prepared for the simultaneous detection of hydroquinone (HQ) and catechol (CT) by incorporating porous tal palm carbon nanosheets (PTPCNS) as the modifier substance on the surface of glassy carbon electrode (GCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to characterize the electrochemical properties of the designed (PTCNS/GCE) sensor. PTPCNS/GCE demonstrated excellent electro‐catalytic property toward resolving the individual voltametric signal of HQ and CT from their mixture. Differential pulse voltammetry (DPV) was applied to quantify the lower limit of HQ and CT. The calculated limit of detection (LOD) was 0.15 µM for HQ with the linear range of 1–300 µM and 0.49 µM for CT with the corresponding linear range 5–225 µM obtained for the proposed sensor. The limit of quantification (LOQ) was found 0.51 µM and 1.63 µM for HQ and CT, respectively. Modified PTPCNS/GCE exhibited excellent selectivity towards HQ and CT even in presence of 10 folds potential interference. The practical applicability of the proposed sensor was analyzed in tap water sample with an excellent recovery of 98–104% for HQ and 99–102% for CT.
The application of zinc oxide-based nanocomposite is one of the novel approaches utilized for the development of electronic devices. The sol-gel and auto combustion procedures were employed to synthesize porous PVA aided ZnO/Fe2O3 nanocomposite (PBNC). The n-type iron (III) oxide was successfully coupled with n-type ZnO. The characterizations conducted to explore the significant changes in the physical properties of as-synthesized materials revealed that the surface area, porosity, and charge transfer capability improvement on the PBNC, compared to ZnO. Using the DTG analysis, 500 °C was confirmed to be the optimal calcination temperature to degrade the PVA polymer after acting as a capping agent and impurities that have a boiling point of less than 500 °C. The XRD pattern and TEM image analysis validated the nanometer range size of the materials (10–70 nm). The SEM image and BET spectral analyses confirmed the porous nature of the PBNC, supporting results obtained from the HRTEM (IFFT) and SAED pattern analysis. The EDXS, XPS, and HRTEM analyses were appliedapplied for Zn, Fe, and O elemental composition and certainty of ZnO. The presence of improved charge transfer property for PBNC, compared to ZnO, has been evidenced by CV and EIS studies. The PBNC also showed enhanced ascorbic acid detection capability compared to ZnO.
Ascorbic acid (vitamin C, AA) is one of the important vitamins and an essential component in human diet. An unusual level of AA is generally a symptom of illness, so developing a sensitive and selective detection method for biological analysis is important. We have developed a new electrochemical sensor for highly selective detection of AA by using flower structured molybdenum disulfide (MoS2) decorated zinc oxide (ZnO)-functionalized multiwall carbon nanotubes (f-MWCNTs). Flower structured MoS2 and ZnO nanoflakes were synthesized by hydrothermal and microwave-assisted solution methods. As synthesized, MoS2/ZnO/f-MWCNTs nanocomposite (surface morphology, particle size and elemental/chemical composition) was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray analysis (EDAX), respectively. The electrochemical properties of the MoS2/ZnO/f-MWCNTs nanocomposite was studied by cyclic voltammetry (CV). MoS2/f-MWCNTs/ZnO modified glassy carbon electrode (GCE) exhibited higher catalytic current for AA at reduced over potential in 0.1 M phosphate buffer solution (PBS). The MoS2/f-MWCNTs/ZnO/GCE responded linearly from 10 to 100 µM AA at 0.21 V. The limit of detection (LOD) was found to be 1.01 μM for AA. In addition, MoS2/f-MWCNTs/ZnO sensor offered fast electron transfer, good anti-interferent ability and stability for AA sensing. Due to good solubility of ƒ-MWCNTs in water, it helped to form nanocomposite with MoS2 and ZnO via carboxyl groups which created numerous catalytic centers that were able to oxidize AA efficiently. This nanocomposite is also blocked the adsorption of other species on the surface of modified GCE. The proposed sensor offers high accuracy, sensitivity, simple fabrication and low cost. Finally, the MoS2/f-MWCNTs/ZnO nanocomposite sensor is used for AA analysis in real samples.
The electrochemical determination of ascorbic acid was carried out at the surface of glassy carbon electrode (GCE) modified by silver nanoparticles (AgNPs):Polyvinylpyrrolidone (PVP). Nanocomposite was evaluated by fourier transform infrared spectroscopy, zeta potential, and X‐ray diffraction. Also, the surface morphologies of the developed electrode were investigated by scanning electron microscopy, and profilometer. The electrochemical performance of AgNPs/PVP/GCE was studied with cyclic voltammetry and electrochemical impedance spectroscopy measurements. The electrochemical studies demonstrated that the electrode had a large surface. Compared with the bare GCE, PVP/GCE, and AgNPs/GCE, the AgNPs/PVP‐modified GCE showed excellent performance for the electrochemical determination of ascorbic acid. At the optimized conditions of differential pulse voltammetry in pH 6.0 of phosphate buffer solution, the modified electrode allowed the determination of ascorbic acid on a potential of 0.54 V vs. Ag/AgCl. Under optimized conditions, the low detection limit of 0.047 μM and working range of 0.2‐1200 μM were obtained at the AgNPs/PVP/GCE. The AgNPs/PVP/GCE allowed to obtain highest peak current values at low concentrations. Moreover, the fabricated electrode also exhibited good repeatability, reproducibility, and stability. The developed electrode was successfully enforced for the analysis of ascorbic acid in banana, kiwi fruit, mango, and pineapple.
