ABSTRACT
Researchers are continually seeking potential alternatives to develop water quality sensors with higher selectivity to obtain the desired performance during real-time deployment. Quantification technologies involving interface materials of distinguishing capacity at elevated matrix complexity are desirable. However, there remains a challenge in designing suitable techniques, methodologies, and appropriate validations to support the grounds for the selection of interface materials of enhanced selectivity. The ability to monitor chlorpyrifos in analytical and commercial grade compounds and in the water matrix using an interface material of suitable states is the focus of this work. Herein, N-(2-hydroxyethyl) ethylenediamine triacetic acid trisodium (N-(2-C2H5O) ED(CH3COONa)3) incorporated with functionalized multiwalled carbon nanotube (f-MWCNT) is reported to provide thermodynamically favorable charge transfer for the quantification of chlorpyrifos residues under varying internal and external conditions with appropriate validations using density functional theory (DFT) and high-performance liquid chromatography (HPLC). The sensor exhibited excellent figures of merit such as limit of detection (LOD) and limit of quantitation (LOQ) of 9.7 pM and 29.4 pM, respectively.
Subject(s)
Chlorpyrifos , Nanotubes, Carbon , Chlorpyrifos/analysis , Nanotubes, Carbon/chemistry , Electrochemical Techniques/methods , Electrodes , Limit of DetectionABSTRACT
Real-time assessment of an active ingredient imidacloprid in the water matrix is critically momentous in monitoring the levels of pesticide contaminants in water bodies. Conventional approaches predominantly deal with the detection of imidacloprid, relying on the purified analytical grade compound. Herein, we report an organic/inorganic composite (f-MWCNT/EDTA) integrated electrochemical sensor for the real-time analysis of analytical grade imidacloprid and extended the performance evaluation in agriculture-purpose imidacloprid compound used commercially by farmers. The choice of the electrode interface significantly supports the electrocatalytic activity towards imidacloprid due to the presence of appropriate energy levels, which are favourable for charge transfer processes validated with Density Functional Theory (DFT) calculations. Further, the performance of the sensor was evaluated in the aquatic environment using river water samples procured from seven different sampling sites and in tap water. The organic/inorganic composite-based electrochemical sensor shows a detection limit of 3.1 × 10-3 pM and three significant wide linear concentration ranges of 0.001-0.05 nM, 0.001-0.04 µM, and 0.001-0.004 mM with apparent interferent resistance. This work paves the way for the real-time environmental monitoring and quantification of imidacloprid by utilizing the highly effective f-MWCNT/EDTA composite catalytic layer.
Subject(s)
Electrochemical Techniques , Nanotubes, Carbon , Edetic Acid , Water/chemistry , Nanotubes, Carbon/chemistry , ElectrodesABSTRACT
The nanostructured ZnO thin films were deposited using spray pyrolysis technique. Formation of polycrystalinity with hexagonal wurtzite structure was observed from the structural study. Highly dense spherical shaped nanoparticles with fine crystallites were observed from the surface morphological studies. The light induced hydrogen peroxide vapour sensing was done using chemi-resistive method and its effect on the sensing response was studied and reported.
ABSTRACT
A dye-sensitized solar cell based on a spray deposited zinc oxide (ZnO) photoanode with Evans blue as a sensitizer was fabricated. Structural analysis confirms the hexagonal wurtzite phase of the ZnO photoanode with c-axis orientation. Surface morphology of the ZnO photoanode shows uniform distribution of spherically-shaped grains, ranging from 18 nm to 25 nm. The power conversion efficiency of the device was measured as 0.1%. Density functional theory was adopted to study the observed photovoltaic performance of the fabricated device. The analysis of the electronic properties of Evans blue dye showed that it has a pronounced effect on the observed device performance.
Subject(s)
Coloring Agents/chemistry , Models, Molecular , Quantum Theory , Solar Energy , Zinc Oxide/chemistry , Electrodes , Electrons , Evans Blue/chemistry , Microscopy, Electron, Scanning , Molecular Conformation , Optical Phenomena , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform Infrared , Vibration , X-Ray DiffractionABSTRACT
Molybdenum trioxide thin films of different thicknesses were prepared on a glass substrate with the chemical spray pyrolysis technique. The X-ray diffraction pattern indicates the formation of an α-MoO3 phase with a polycrystalline nature. The field-emission scanning electron micrograph of the surface indicates nanostructured lamellar crystallites. The trimethylamine vapour sensing property of the film was studied by the chemiresistive method at room temperature (≈ 30°C). Film with a thickness of 520 nm shows a response of 12% for 0.5 ppm of TMA vapour in 54% relative humidity, with response and recovery times of 32s and 15s, respectively. The detection limit and sensing response of the α-MoO3 thin film in a mixed environment were analysed and reported.
Subject(s)
Biosensing Techniques , Methylamines/isolation & purification , Molybdenum/chemistry , Oxides/chemistry , Gases/chemistry , Methylamines/chemistry , Nanostructures/chemistry , Surface Properties , X-Ray DiffractionABSTRACT
The present work aims at understanding the structural stability of Cadmium oxide (CdO) nano-particles of different sizes due to its potential application in the field of optoelectronics and gas sensing. The stable structures of the (CdO)(n) (n=1-8) have been fully optimized with Gaussian 03W program package at B3LYP/6-31G level, and it is found that, for n=1-5, the ring structures is more stable, and for n>5, the three-dimensional structures is more stable than the ring structure. But the stable ring geometries for n>9 are found to be difficult, because the ring structures become more complicated. The present calculation also shows that, with the growth of the clusters, 3D structures are more favorable in energy, and the Cd and O atom tend to adopt higher coordination numbers. Moreover, the simulated IR spectra help to distinguish the ring structures from the cubic or hexagonal packing structures.
