Instrumental Techniques for Characterization of Molybdenum Disulphide Nanostructures

In-situ growth of MOF-derived Co3S4@MoS2 heterostructured electrocatalyst for the detection of furazolidone

The over-exploitation of antibiotics in food and farming industries ruined the environmental and human health. Consequently, electrochemical sensors offer significant advantages in monitoring these compounds with high accuracy. Herein, MOF-derived hollow Co3S4@MoS2 (CS@MS) heterostructure has been prepared hydrothermally and applied to fabricate an electrochemical sensor to monitor nitrofuran class antibiotic drug. Various spectroscopic methodologies have been employed to elucidate the structural and morphological information. Our prepared electrocatalyst has better electrocatalytic performance than bare and other modified glassy carbon electrodes (GCE). Our CS@MS/GCE sensor exhibited a highly sensitive detection by offering a low limit of detection, good sensitivity, repeatability, reproducibility, and stability results. In addition, our sensor has shown a good selectivity towards the target analyte among other potential interferons. The practical reliability of the sensor was measured by analyzing various real-time environmental and biological samples and obtaining good recovery values. From the results, our fabricated CS@MS could be an active electrocatalyst material for an efficient electrochemical sensing application.

Thermal and hydraulic performance of ZnO/EG based nanofluids in mini tubes of different diameters: An experimental investigation

The present experimental study investigates the thermal and hydraulic performance of Ethylene Glycol (EG)-based ZnO nanofluids (NFs) in circular minichannel test sections, each of 330 mm in length and 1.0-2.0 mm inner diameters. The experiments were conducted under steady-state constant heat flux and laminar flow conditions. The stable ZnO/EG-based NFs were synthesized using a standard two-step method in varying nanoparticles (NPs) loadings (0.012-0.048 wt%). The morphological characteristics, crystal structure, and specific surface area (SSA) showed that the NPs were sized in nm, possessing excellent crystal structure and enhanced surface area. Thermal conductivity (TC) and viscosity (VC) of the NFs were examined in the 20-60 °C temperature range. Both TC and VC possessed an increasing trend with the rise in concentration of the NPs. However, with the temperature rise, TC increased while the VC decreased and vice versa. The highest enhancements in TC and VC were 14.38 % and 15.22 %, respectively, at 40 °C and 0.048 wt% of NPs loading. The highest enrichment recorded in the local and average heat transfer coefficient (HTC) were 14.80 % and 13.48% in a minichannel with 1.0 mm inner diameter, respectively. It was directly proportional to the NPs loading and volume flow rate of the NFs. The friction factor was also directly proportional to the test section's inner cross-sectional area, while the pressure gradient showed an inverse behavior. An inverse relationship was recorded for the volume flow rate of the NFs and vice versa. Maximum friction factor and the pressure drop for all three minichannel test sections were recorded as 34.58 % and 32.16 %, respectively. The well-known Shah correlation predicted the local and average HTC within ±15.0 %, while the friction factor and the pressure gradient were well predicted by the Darcy correlation within the ±10.0 % range.

3D silver metallized nanotrenches fabricated by nanoimprint lithography as flexible SERS detection platform

We report the development of highly sensitive substrates with great potential as Surface-enhanced Raman scattering (SERS) spectroscopy detection platforms, consisting of nanoimprint lithography (NIL) fabricated nanotrenches in plastic and covered by nanostructured silver (Ag) films with thicknesses in the 10-100 nm range deposited by direct current (DC) sputtering. The Ag film thickness was increased by using sequential deposition times and its contribution to the obtained enhancement factor was determined. The morphological and structural properties of the metalized nanotrenches were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Crystal violet (CV) was used as analyte to test the SERS activity of the substrates prepared with or without the nanoimprinted pattern. Our original approach was to determine the resulted SERS enhancement from the synergy of three key aspects: the Ag metallization of cheap, flexible substrates, the effect of increasing the Ag film thickness and the periodic nanotrenches imprinted by NIL as substrate. We found a dramatical contribution in the SERS signal of the periodical Ag nanopattern in comparison to the Ag film quantified by a calculated enhancement factor (EF) up to 10⁷ in case of the SERS detection platform with a 25 nm Ag layer on top of the periodic nanotrenches. The contribution of plasmonic nanostructures contained in the Ag films as well as the contribution of the periodical nanopatterned trenches was assessed, as a cumulative effect to the first contribution. This substrate showed a considerably lower limit of detection (LOD) for SERS, down to 10 pM, much better uniformity as well as more reproducible signals in comparison with the other thicknesses of the metallic film.