Sensitive Detection of Thiourea Hazardous Toxin with Sandwich-Type Nafion/CuO/ZnO Nanospikes/Glassy Carbon Composite Electrodes

In this research study, we developed a voltammetric electrochemical sensor probe with a copolymer Nafion (Sulfonated Tetrafluoroethylene-based Fluoro-polymer) decorated with hydrothermally prepared sandwich-type CuO/ZnO nanospikes (NSs) onto a glassy carbon electrode (GCE) for reliable thiourea (TU) detection. The detailed characterizations in terms of structural morphology, binding energy, elemental compositions, grain size and crystallinity for synthesized NSs were performed by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. The differential pulse voltammetric (DPV) analysis for TU showed good linearity at current-versus-TU concentration on the calibration plot in the 0.15~1.20 mM range, which is defined as a dynamic detection range (LDR) of TU in a phosphate buffer solution. Considering the slope of LDR over the GCE-coated NSs surface area (0.0316 cm2), the TU sensor sensitivity (0.4122 µA µM-1 cm-2) was obtained. Besides this, the low limit (LOD) for TU detection was calculated and found to be 23.03 ± 1.15 µM. The fabricated Nafion/CuO/ZnO NSs/GCE sensor probe was created as a reliable sensor based on reproducibility, interference effect, stability and response time. Real bio-samples were investigated and the results confirm the anticipated reliability of the TU sensor probe. Thus, this is a noble way to develop enzyme-free electrochemical sensors that could be an alternative approach for the detection of chemicals in the field of enzyme-free biosensor development technology.

Photocatalytic performance, anti-bacterial activities and 3-chlorophenol sensor fabrication using MnAl2O4·ZnAl2O4 nanomaterials

A MnAl₂O₄·ZnAl₂O₄ nanomaterial was synthesized by co-precipitation and characterized by XRD, SEM, EDS, TEM, AFM, FTIR, PL, CV and EIS. The photocatalytic activity of the nanocomposite against MV dye and its MDR anti-bacterial functions were studied. The nanocomposite shows excellent photocatalytic as well as anti-bacterial activity. A MnAl₂O₄·ZnAl₂O₄ nanomaterial/Nafion/GCE electrode was fabricated and implemented as the working electrode of a 3-CP sensor. The sensor exhibited good sensitivity, with the lowest detection limit, fast response time, large linear dynamic range (LDR), and long-term stability in the chemical environment. The estimated sensitivity is 70.07 μA mM^-1 cm^-2. The LDR, limit of detection (LOD), and limit of quantification (LOQ) are 0.1 nM to 0.01 M, 0.0014 ± 0.0001 nM, and 0.004 nM, respectively. The MnAl₂O₄·ZnAl₂O₄ nanomaterial/Nafion/GCE is a promising fabricated sensor probe for the selective detection of 3-CP for the environmental safety and healthcare fields on a large scale.

Photocatalytic, anti-bacterial performance and development of 2,4-diaminophenylhydrazine chemical sensor probe based on ternary doped Ag·SrSnO3 nanorods

Ag·SrSnO₃ NRs is an excellent photocatalyst, kills both Gram positive and Gram negative bacteria. The 2,4-DAPHyd sensor fabricated by layered Ag·SrSnO₃ NRs onto GCE shows high sensitivity (7.5854 μA μM⁻¹ cm⁻²); LDR, 0.1 nM~0.01 mM & LOD, 96.13 ± 4.81 pM.

Enhanced visible light-mediated photocatalysis, antibacterial functions and fabrication of a 3-chlorophenol sensor based on ternary Ag2O·SrO·CaO

A novel multi-metal oxide nanocomposite, Ag2O·SrO·CaO, was synthesized by a facile co-precipitation method followed by calcinations. The synthesized nanocomposite was characterized by XRD, FESEM, EDS, TEM, FTIR spectroscopy and photoluminescence (PL) spectroscopy. The composite showed enhanced photocatalytic activity under visible light irradiation and excellent anti-bacterial performance against both Gram-positive and Gram-negative bacteria. Here, the synthesized Ag2O·SrO·CaO nanomaterials were deposited on a glassy carbon electrode (GCE) in the form of a thin film to fabricate the desired electrochemical sensor and subjected to I-V analysis of 3-chlorophenol (3-CP) in a phosphate buffer solution (PBS). A calibration curve was plotted from the linear relation of current versus concentration and used to calculate the sensitivity (8.9684 μA μM-1 cm-2), linear dynamic range (LDR, 0.1 nM to 0.01 mM) and lower limit of detection (DL, 97.12 ± 4.86 pM). The analytical parameters of the sensor such as response time, reproducibility and long-term stability in the detection of 3-CP were reliable. Finally, it was used to analyze real samples collected from various environmental sources and found to be acceptable.

Efficient selective 4-aminophenol sensing and antibacterial activity of ternary Ag2O3·SnO2·Cr2O3 nanoparticles

The electrochemical oxidation of 4-AP based on Ag₂O₃·SnO₂·Cr₂O₃ NPs/binder/GCE sensor.

ZIF-8 derived ZnO/Zn6Al2O9/Al2O3 nanocomposite with excellent photocatalytic performance under simulated sunlight irradiation

The ZIF-8 derived ZnO/Zn₆Al₂O₉/Al₂O₃ nanocomposite exhibits an unprecedented photocatalytic degradation activity toward MO of high concentration.

Enhanced photocatalytic activity and ultra-sensitive benzaldehyde sensing performance of a SnO2·ZnO·TiO2 nanomaterial

The synthesis of a ternary SnO₂·ZnO·TiO₂ nanomaterial (NM) by a simple co-precipitation method and its potential applications as an efficient photocatalyst and chemical sensor have been reported. The synthesized nanomaterial was fully characterized by XRD, SEM, EDS, XPS, FTIR, AFM and photoluminescence studies. This nanomaterial exhibited enhanced efficiency in photo-catalysis of Methyl Violet 6b (MV) dye degradation. The observed photocatalyst efficiency of the SnO₂·ZnO·TiO₂ nanomaterial was 100% under UV light at pH 9. Moreover, it lost around 12% efficiency over five reuses. The PL properties with changing excitation energy were also reported. Glassy carbon electrode (GCE) was modified with the SnO₂·ZnO·TiO₂ nanomaterial by an efficient electrochemical technique to develop a chemical sensor for selective benzaldehyde. Hazardous benzaldehyde was carefully chosen as a target analyte by a selectivity study; it displays a rapid response towards the SnO₂·ZnO·TiO₂/Nafion/GCE sensor probe in electrochemical sensing. It also shows superb sensitivity, an ultra-low detection limit, long-term stability, and very good repeatability and reproducibility. In this study, a linear calibration plot was obtained for 0.1 nM to 1.0 mM aqueous benzaldehyde solutions, with a sensitivity value of 4.35 nA μM⁻¹ cm⁻² and an exceptionally low detection limit (LOD) of 3.2 ± 0.1 pM (S/N = 3). Hence, a chemical sensor modified with SnO₂·ZnO·TiO₂/GCE may be a promising sensor in the determination of toxic chemicals in the environmental and healthcare fields.

Schematic of a GCE fabricated with SnO₂·ZnO·TiO₂ NMs/Nafion/GCE using a conducting Nafion binder and its electrochemical response as a benzaldehyde sensor.

Wet-chemically prepared low-dimensional ZnO/Al2O3/Cr2O3 nanoparticles for xanthine sensor development using an electrochemical method

A reliable xanthine (XNT) chemical sensor was fabricated using a facile wet-chemical method (by co-precipitation) to prepare ZnO/Al₂O₃/Cr₂O₃ nanoparticles (NPs) in an alkaline medium at low temperature. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-vis) were implemented for detailed characterization of the NPs. To fabricate the working electrode as a XNT chemical sensor probe, a glassy carbon electrode (GCE) with a 0.0316 cm² surface area was coated with an ethanolic slurry of the prepared ZnO/Al₂O₃/Cr₂O₃ NPs to make a thin layer and used to analyse XNT in a phosphate buffer system. To evaluate the analytical performances of the XNT chemical sensor, the calibration curve of XNT was plotted as the relationship of current versus the concentration of XNT. The plotted calibration curve was found to be linear over the LDR (linear dynamic range) of 0.05 nM to 5.0 μM. The assembled XNT electrochemical sensor exhibited the highest sensitivity (70.8861 μA μM⁻¹ cm⁻²), the lowest detection limit (1.34 ± 0.07 pM), good reproducibility performance with high accuracy and long-term stability with standard results under ambient conditions. This is a simple route to selectively detect XNT with wet-chemically prepared co-doped ZnO/Al₂O₃/Cr₂O₃ nanomaterials using a reliable electrochemical method at a large scale for safety within healthcare fields.

This is a simple route to detect the selective xanthine with wet-chemically prepared co-doped ZnO/Al₂O₃/Cr₂O₃ nanomaterials by reliable electrochemical method at large scales for the safety of healthcare fields.

Fabrication of a 2,4-dinitrophenol sensor based on Fe3O4@Ag@Ni nanomaterials and studies on their antibacterial properties

Scheme representing (a) MO coated GCE, (b) theoretical I–V response, (c) observed I–V responses by the MO/Nafion/GCE, and (d) proposed detection mechanism of 2,4-DNP.