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In this article, using polyvinyl alcohol (PVA) and sodium hexametaphosphate (SHP) as a surfactant solution, tetragonal SnO2 nanoparticles (NPs) were synthesised using the hydrothermal technique. NPs resulting from this process are named Sn-SHP and Sn-PVA.X-ray diffraction study revealed tetragonal crystal structure for both Sn-SHP and Sn-PVA nanoparticles, matching well with the JCPDS Card No. 88-0287. Scanning electron microscopy (SEM) showed rod-shaped Sn-SHP NPs, whereas Sn-PVA NPs have flower-like forms. A band gap energy of 3.71 and 3.84 eV was measured for the Sn-SHP and the Sn-PVA nanoparticles. The various oxidation states of SnO2 were confirmed by XPS spectra in order to confirm its oxidation states. The electrodes were analysed by using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical ion spectroscopy (EIS) in 6 M KOH electrolytes. For Sn-PVA electrodes, the computed specific capacitance (Cs) values are 330.52, 71.25, 27.34, and 18.85 Fg−1 at scan rates of 2, 10, 30, and 50 mVs−1; whereas for Sn-SHP electrodes, the obtained values are 256.24, 55.46, 21.04, and 14.45 Fg−1 at scan rates of 2, 10, 30, and 50 mVs−1. Additionally, from the GCD curves demonstrate that the Sn-PVA electrode has Cs of 126, 98, 81, and 71 Fg−1, and Sn-SHP electrodes revealed Cs of 75.65, 66.44, 48.69, and 25.97 Fg−1 at current density of 1, 2, 4, and 6 Ag−1, respectively. Galvanostatic charge–discharge curves for Sn-SHP and Sn-PVA NPs were traced in a potential window ranging from 0.03 to 0.4 V, and it was ascertained that Sn-PVA with flower shaped nanoparticles retains Sc of 126 Fg−1 at current density of 1 Ag−1, making it potential candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

MXene, a two-dimensional (2D) material composed of transition metal carbides (TMCs) and nitrides, have fascinated substantial scientific interest. This increased interest results from their exceptional properties, which include extraordinary conductivity, transparency, outstanding absorbing capacity, and significant charge storage capacities. In this work, the MXene-doped vanadium copper sulfide (VCuS) was synthesized through the hydrothermal method. In three electrode measurement system, the VCuS/MXene composite electrode showed exhibited a specific capacity (Qs) of 1620 Cg−1. As application point of view, the hybrid device is designed and measured the electrochemical properties. The hybrid device showed the remarkable Qs of 1528 C.g−1, power density (Pd) of 2347 Wkg−1 and an energy density (Ed) of 34.99 Whkg−1. Further, the VCuS/MXene//AC device is measured up to 6000 cycles to check the stability and durability. The device showed the capacity retention (CR) of 88.5% and a high Coulombic efficiency of 82.6%. Additionally, the VCuS/MXene electrode material is utilized as an electrochemical glucose sensor for the precise detection of H2O2 down to a minimal concentration of H2O2/mm, exhibiting exceptional precision. The use of multifunctional VCuS/MXene nanocomposite electrode material presents novel possibilities for the construction of hybrid energy harvesting systems. [ABSTRACT FROM AUTHOR]

Because of their many advantages, such as simplicity of handling, affordability, and environmental friendliness, green magnetic nanoparticles (GMNPs) are currently receiving more attention than prevailing magnetic nanoparticles (MNPs). The synthesis and application of GMNPs inspired by biological systems are encouraged by rising ecological consciousness and stringent environmental restrictions and also deal with in detail in this manuscript. The current report presents the biological and environmental uses of GMNPs in-depth. Numerous biomedical applications, including imaging and diagnosis, cancer therapy, immunoassay, genetic engineering, and supported enzymes (proteins and peptides), among others, successfully use GMNPs. The GMNPs would be coupled with tiny sensors, microsystems, and microfluidics modules to boost the signal sensitivity for the identification of environmental contaminants, diseases, poisons, drugs, and trace biomarkers from clinical, environmental, and dietary examples. The GMNPs were essential elements in gene delivery and gene therapy initiatives, among other genetic engineering endeavors. They have also been extensively used for environmental applications such as wastewater treatment, organic pollutants decontamination, electrochemical sensing, industrial and radioactive wastes treatment, pollutant adsorption and removal etc. The use of GMNPs, particularly biosynthesized MNPs, is also believed to be more cost-effective than the majority of regularly used traditional MNPs. In addition, Green magnetic nanoparticles applied as supported enzymes, proteins and peptides catalyst, positron emission tomography, computed tomography, magnetic resonance imaging, theranostics, thermo-chemotherapy, electrochemical immunoassay and efficient detection of coronavirus is a significant issue in modern analytical chemistry and other fields. The opportunities of using GMNPs in the place of traditional MNPs have also been proposed. [ABSTRACT FROM AUTHOR]

The thermal enhancement and pressure drop in a circular tube with radially-arrayed winglet vortex generator (VG) mounted inside at different orientations were experimentally studied. A series of four winglet rings containing VGs were on the inner surface of the tube at different sections. The effects of winglet attack angles β (0–45°), pitch ratios PR (1.6–4.8), porosity ratio γ (0–20%), winglet length L (10–20 mm), and inclination angle α (0–30°) on heat transfer and pressure drop characteristics were carefully examined. The study was carried out at Reynolds numbers (Re) ranging from 6 × 103 to 2.7 × 104 nestling in the turbulent flow regime. Results showed a significant effect of the winglets on the heat transfer enhancement and pressure penalty compared to the smooth tube. Experiments further revealed that as the length or attack angle of winglets increased, both Nusselt number (Nu) and friction factor (f) were intensified. When it turned to pitch ratio and inclination angle of winglets, the trend became adverse. By comparing the contribution of different winglet parameters, it is preferable to optimize the pitch ratio (PR) other than length, inclination angle (α) nor attack angle (β) for a higher thermal enhancement. The case of small porosity ratio (γ = 10%) at a low Re yields the maximum thermal enhancement of 1.26. Empirical correlations for Nu and f were generated for the winglets based on experimental data. [ABSTRACT FROM AUTHOR]

The application of scanning electrochemical microscopy has increased recently in corrosion studies. The electrochemical activity image is usually generated indirectly by measuring the rate of reaction of a mediator which is not a part of the studied system. This work aims at developing an experimental technique to use scanning electrochemical microscopy without using electrochemically active species. Galvanic corrosion of ductile cast iron was studied by pulsing both the sample and tip electrode to cathodic and anodic regions. By tuning the pulse parameters, the current response of the tip differs in the vicinity of iron and graphite, leading to the imaging of the oxidation/reduction processes. [ABSTRACT FROM AUTHOR]