Showing papers by "Adisorn Tuantranont published in 2022"

Fast, sensitive and selective simultaneous determination of paraquat and glyphosate herbicides in water samples using a compact electrochemical sensor.

Abstract: We report a new ready-to-use sensor for simultaneous determination of paraquat (PQ) and glyphosate (GLY) based on a graphite screen-printed electrode modified with a dual-molecularly imprinted polymer coated on a mesoporous silica-platinum core. Amino-mesoporous silica nanoparticles (MSN-NH2) were first synthesized by a simple co-condensation method using tetraethyl orthosilicate and 3-aminopropyltrimethoxysilane. PtNPs were then decorated on the surface of MSN-NH2 by chemical reduction. Finally, the dual-MIP was successfully coated on the MSN-PtNP core. This 3D-surface-imprinting strategy enhances the conductivity and monodispersity of the MSN-PtNPs@d-MIP. Quantitative analysis was performed by differential pulse voltammetry with an oxidation current appearing at -0.95 V for PQ and +0.97 V for GLY. The dual-MIP sensor shows good linear calibration curves in the range of 0.025-500 μM for both analytes with detection limits of 3.1 nM and 4.0 nM for PQ and GLY, respectively. The dual-MIP sensor shows high selectivity and specificity, attributed to the increased affinity of the imprinted cavities formed on the polymer film for the target PQ and GLY molecules. The proposed dual-MIP sensor was successfully applied to detect PQ and GLY concentrations simultaneously in water samples. The ready-to-use dual-MIP sensor is well suited for water-quality control and on-site applications without sophisticated instrumentation.

Photocatalytic efficiency under visible light of a novel Cu–Fe oxide composite films prepared by one-step sparking process

Abstract: Copper-iron (Cu-Fe) oxide composite films were successfully deposited on quartz substrate by a facile sparking process. The nanoparticles were deposited on the substrate after sparking off the Fe and Cu tips with different ratios and were then annealed at different temperatures. The network particles were observed after annealing the film at 700 °C. Meanwhile, XRD, XPS and SAED patterns of the annealed films at 700 °C consisted of a mixed phase of CuO, γ-Fe2O3, CuFe2O4 and CuFe2O. The film with the lowest energy band gap (Eg) of 2.56 eV was observed after annealing at 700 °C. Interestingly, the optimum ratio and annealing temperature show the photocatalytic activity under visible light higher than 20% and 30% compare with the annealed TiO2 at 500 and 700 °C, respectively. This is a novel photocatalyst which can be replaced TiO2 for photocatalytic applications in the future.

Copper Zinc Sulfide (CuZnS) Quantum Dot-Decorated (NiCo)–S/Conductive Carbon Matrix as the Cathode for Li–S Batteries

Abstract: Sulfur composites consisting of electrochemical reactive catalysts/conductive materials are investigated for use in lithium–sulfur (Li–S) batteries (LSBs). In this paper, we report the synthesis, physicochemical and electrochemical properties of CuZnS quantum dots (CZSQDs) decorated with nickel–cobalt–sulfide ((NiCo)–S)) mixed with reduced graphene oxide (rGO)/oxidized carbon nanotube (oxdCNT) (rGO/oxdCNT) ((NiCo)–S@rGO/oxdCNT) composites. These composites are for the purpose of being the sulfur host cathode in Li–S batteries. The as-prepared composites showed a porous structure with the CZSQDs being uniformly found on the surface of the rGO/oxdCNT, which had a specific surface area of 26.54 m2/g. Electrochemical studies indicated that the (NiCo)–S@rGO/oxdCNT cells forming the cathode exhibited a maximum capacity of 1154.96 mAhg−1 with the initial discharge at 0.1 C. The smaller size of the CZSQDs (~10 nm) had a positive effect on the CZSQDs@(NiCo)–S@rGO/oxdCNT composites in that they had a higher initial discharge capacity of 1344.18 mAhg−1 at 0.1 C with the Coulombic efficiency being maintained at almost 97.62% during cycling. This latter property is approximately 1.16 times more compared to the absence of the Cu–Zn–S QD loading. This study shows that the CuZnS quantum dots decorated with a (NiCo)–S@rGO/oxdCNT supporting matrix-based sulfur cathode have the potential to improve the performance of future lithium–sulfur batteries.

Conversion of Carbon Dioxide into Chemical Vapor Deposited Graphene with Controllable Number of Layers via Hydrogen Plasma Pre-Treatment

Abstract: In this work, we report the conversion of carbon dioxide (CO2) gas into graphene on copper foil by using a thermal chemical vapor deposition (CVD) method assisted by hydrogen (H2) plasma pre-treatment. The synthesized graphene has been characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show the controllable number of layers (two to six layers) of high-quality graphene by adjusting H2 plasma pre-treatment powers (100–400 W). The number of layers is reduced with increasing H2 plasma pre-treatment powers due to the direct modification of metal catalyst surfaces. Bilayer graphene can be well grown with H2 plasma pre-treatment powers of 400 W while few-layer graphene has been successfully formed under H2 plasma pre-treatment powers ranging from 100 to 300 W. The formation mechanism is highlighted.

A compact N-nitrosodiphenylamine imprinted sensor based on a Pd nanoparticles-MIP microsphere modified screen-printed graphene electrode

Abstract: Herein, we report the fabrication of a compact voltammetric sensor for the sensitive and selective determination of N-nitrosodiphenylamine (NDPhA) based on a screen-printed graphene electrode modified with a molecularly imprinted polymer coating on a palladium nanoparticle core ([email protected]/SPGrE). In addition, a novel approach for 3D-imprinting of NDPhA on the PdNPs surface is presented. PdNPs were first synthesized by chemical reduction using sodium borohydride. Then, Core-shell polymerization was achieved by successively coating the surface of PdNPs with poly(vinylpyrrolidone) and terminating with an MIP consisting of poly(N-Isopropylacrylamide)-co-trimethylolpropane trimethacrylate. Morphological, structural, and electrochemical characterization reveals that the as-prepared micro-sized spherical [email protected] has a uniform, high electro-catalytic activity and a specific surface area with many NDPhA imprinted sites. We constructed the compact NDPhA imprinted sensor by coating the SPGrE surface with [email protected] Quantitative analysis was performed by linear sweep anodic stripping voltammetry (LSASV) using a deposition potential of +0.02 V for 60 s. The linear working ranges for NDPhA measurements were 0.01–0.1 μM (r2 = 0.996) and 0.1–100 μM (r2 = 0.992) with corresponding sensitivities of 51.935 and 0.821 (μA s) µM−1, respectively. The system provides a good precision of %RSD 1.67% with an estimated detection limit (3Sb, n = 3) of 0.0013 μM. The intraday and inter-day accuracy (%bias) of the certified reference material (CRM) are −0.74% and −1.01%, respectively. We demonstrate the successful application of the fabricated compact sensor to determine NDPhA in beverage and synthetic samples. The compact NDPhA imprinted sensor can provide an alternative approach to food quality control.

Improved Performance of Lithium–Sulfur Batteries Using Nitrogen-Doped Reduced Graphene Oxide-Coated Separators with Optimized Nitrogen Content

Abstract: In this work, a hydrothermally synthesized nitrogen-doped reduced graphene oxide (N-rGO) layer as a barrier to polysulfide diffusion was coated on a commercial polypropylene (PP) separator to enhance charge capacity and cycling stability of Li–S batteries. Coin-cell Li–S batteries were fabricated using sulfur/carbon nanotube/N-rGO cathode with 70% sulfur loading, lithium foil anode, lithium bis(trifluoromethanesulfonyl) imide-based electrolyte, and N-rGO-coated PP separators with varying N contents in the range of 0–20 wt %. Galvanostatic charge–discharge measurements demonstrated that the charge capacity and capacity retention at various current densities improved substantially with increasing N content from 0 to 15 wt % before slightly deteriorating as the N content increases further. The cell with the optimal N-rGO-modified separator delivered high initial discharge capacities of 1563 mA h g–1 at 0.1 C and 1291 mA h g–1 at 1 C and high capacity retentions of 83.7% after 200 cycles at 0.1 C and 79.8% after 500 cycles at 1 C. Chemical analyses of materials verified that the improved energy storage performances by the N-rGO-coated separator could be attributed to the strong affinity of lithium polysulfides around N sites on N-rGO, leading to improved redox kinetics and effective suppression of the polysulfide shuttle effect. Therefore, the hydrothermally synthesized N-rGO-modified separator is highly promising as a means to achieve high-performance and long-life Li–S batteries suitable for mass production and commercialization.

An alternative ready-to-use electrochemical immunosensor for point-of-care COVID-19 diagnosis using graphene screen-printed electrodes coupled with a 3D-printed portable potentiostat

Abstract: A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a cause of worldwide Coronavirus 2019 (COVID-19) disease pandemic. It is thus important to develop ultra-sensitive, rapid and easy-to-use methods for the identification of COVID-19 infected patients. Herein, an alternative electrochemical immunosensor based on poly(pyrrolepropionic acid) (pPPA) modified graphene screen-printed electrode (GSPE) was proposed for rapid COVID-19 detection. The method was based on a competitive enzyme immunoassay process utilizing horseradish peroxidase (HRP)-conjugated SARS-CoV-2 as a reporter binding molecule to compete binding with antibody against the SARS-CoV-2 receptor binding domain (SARS-CoV-2 RBD) protein. This strategy enhanced the current signal via the enzymatic reaction of HRP-conjugated SARS-CoV-2 RBD antibody on the electrode surface. The modification, immobilization, blocking, and detection processes were optimized and evaluated by amperometry. The quantitative analysis of SARS-CoV-2 was conducted based on competitive enzyme immunoassay with amperometric detection using a 3D-printed portable potentiostat for point-of-care COVID-19 diagnosis. The current measurements at -0.2 V yielded a calibration curve with a linear range of 0.01-1500 ng mL-1 (r2 = 0.983), a low detection limit of 2 pg mL-1 and a low quantification limit of 10 pg mL-1. In addition, the analyzed results of practical samples using the developed method were successfully verified with ELISA and RT-PCR. Therefore, the proposed portable electrochemical immunosensor is highly sensitive, rapid, and reliable. Thus, it is an alternative ready-to-use sensor for COVID-19 point-of-care diagnosis.

Enhanced NO2‐Sensing Properties of Cu‐Loaded SnO2 Nanoparticles Synthesized via Precipitation and Impregnation Methods

Abstract: Herein, NO2 noxious gas sensors based on precipitation/impregnation synthesized SnO2 nanoparticles loaded with Cu2O (Cu2O–SnO2) are presented. The particle properties are characterized by nitrogen adsorption, X‐ray spectroscopic, and microscopic analyses. The NO2‐sensing performances in terms of sensor response, response times, selectivity, and stability are optimized by varying Cu contents. The optimal sensing film (1.0 wt%Cu–SnO2) shows a high sensor response of ≈5680–5 ppm of NO2 at a low operating temperature of 200 °C. In addition, 1.0 wt%Cu–SnO2 sensor exhibits very high NO2 selectivity against SO2, H2S, C2H5OH, H2, C2H2, C2H4, and CH4 compared with unloaded one. Therefore, the 1.0 wt%Cu–SnO2 sensor is a promising candidate for highly sensitive and selective detection of NO2.

Acute Kidney Injury Detection using Real Human Urine NGAL Biomarker Sensor based on 3D Graphene

Abstract: Acute kidney injury (AKI) is not a specified symptom in the early stages. Frequency of AKI occurrence is highly correlated to Chronic Kidney Disease (CKD). Therefore, development of non-invasive, ultra-sensitive, and highly accurate sensing platform is crucial for early AKI diagnosis. Serum creatinine (SCr) level usually takes 24-72 hours to response to the incident of AKI. Meanwhile, urine Neutrophil Gelatinase-Associated Lipocalin (NGAL) takes only 2 hours to response after the AKI occurrence. In this work, we investigated the use of microporous graphene and dipole-dipole enhancement between graphene/nickel layers to enhance electrode sensitivity for urine NGAL level determination. Selectivity was assured using enzymatic electrochemistry. Once NGAL level was measured, a doctor can diagnose AKI under additional information on patient’s conditions. The result is promising since the detection range was 0.110 to 93.9 ng/ml and the correlation coefficient is 0.8235. The detection covered AKI primary diagnostic cutoff level at 87 ng/ml in urine. The electrochemical immunosensor was able to determine NGAL in Urine with results compared to those provided by the standard ELISA method. This work is a part of development of handheld NGAL determination strip in human urine samples and prepared portable NGAL sensing devices. Despite our investigation’s limitation, the acquired data indicates that non-invasive acute kidney injury detection using actual human urine with graphene foam/nickel-based electrochemical sensor should be further explored as an auxiliary diagnostic tool for AKI.

A Plastic Based Electrowetting on Dielectric Microchip Integrate with Electrochemical Sensor by Screen Printing

Abstract: In this research, a plastic based electrowetting on dielectric (EWOD) microchip with electrochemical sensor was studied. The microchip was designed, fabricated and experimental studied for the chemical analysis. For the design, the microchip was designed with the T-junction base for develop to the new junction that can analyte four droplets in one time and use three electrodes as electrochemical sensor in the end of the junction. The electrochemical sensor comprising three electrodes, including carbon working, carbon counter, and silver/silver chloride reference electrodes. The EWOD integrate with electrochemical sensor was fabricated by screen sprint technique and was tested to possibility of moving droplets on the microchip and chemical analysis with digital operator.The screen-printed EWOD microchip with integrated screen-printed carbon electrochemical sensor could be a promising alternative for low-cost automated chemical analyses