Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles

Water desalination using stainless steel meshes coated with layered double hydroxide/graphene oxide nanocomposite

Coated stainless steel meshes with layered double hydroxides and graphene oxide nanocomposites (LDH/GO) were used as desalination membranes. The nature of stainless steel mesh allows a greater amount of sorbent to be coated on the surface using sol-gel technique and increases the adsorption capacity of ions and the efficiency of desalination. These substrates improve the contact surface area so that approximately 5 min is required for the desalination process. The LDH/GO stainless steel mesh exhibited excellent corrosion resistance and tensile strength of 99.9% and 112 MPa, respectively. To achieve the best desalination efficiency, different parameters were optimized, including the ratio of GO to LDH in the nanocomposites, the number of mesh layers, NaCl concentrations, and process cycles. The maximum adsorption capacity for the NaCl was 555.5 mg g-1 . The results revealed that LDH/GO nanocomposite was able to remove (94.3 ± 0.5) % of the NaCl under the optimum conditions. The proposed method was used to successfully remove Na+ , Mg+2 , Ca+2 , and K+ cations from seawater, with the yields of 92.3%, 92.5%, 91.2%, and 90.2%, respectively. PRACTITIONER POINTS: The salts are removed via interaction between salt ions and functional groups on the LDH/GO nanocomposite surface. A high amount of adsorbent loaded on the surface of steel mesh leads to an improvement in the adsorption capacity. The sol-gel technique strengthens the LDH/GO nanocomposites on the surface of steel mesh.

Synthesis of N-acyl glycine surfactant from palm oil as green repellent and toxicant to termite (Microcerotermes diversus)

This study described for the first time, the synthesis of a greener, safer, and more effective termiticide using a bio-based surfactant, N-acyl glycine derived from palm oil for the control of Microcerotermes diversus. Laboratory findings showed that the highest repellent activity was observed in N-acyl glycine surfactant (83.33%) at 50 ppm. In addition, N-acyl glycine surfactant also exhibited substantial time and concentration-dependent anti-termiticidal activity in which the highest termite mortality was observed after 3 days of exposure at 50 ppm of the surfactant (100%). Furthermore, 32.49 ppm concentration of N-acyl glycine surfactant (LC50 = 32.49 ppm) attained 50% of termite lethality. The current innovated termiticide with the use of N-acyl glycine surfactant offers a better efficacy, lower cost, and prevents the use of dangerous termiticides that are critical in creating a more sustainable environment, and controls Microcerotermes diversus at the same time.

Anomalous metal vaporization from Pt/Pd/Al2O3 under redox conditions

Al2O3-supported Pt/Pd bimetallic catalysts were studied using in situ atmospheric pressure and ex situ transmission electron microscopy. Real-time observation during separate oxidation and reduction processes provides nanometer-scale structural details - both morphology and chemistry - of supported Pt/Pd particles at intermediate states not observable through typical ex situ experiments. Significant metal vaporization was observed at temperatures above 600 °C, both in pure oxygen and in air. This behavior implies that material transport through the vapor during typical catalyst aging processes for oxidation can play a more significant role in catalyst structural evolution than previously thought. Concomitantly, Pd diffusion away from metallic nanoparticles on the surface of Al2O3 can also contribute to the disappearance of metal particles. Electron micrographs from in situ oxidation experiments were mined for data, including particle number, size, and aspect ratio using machine learning image segmentation. Under oxidizing conditions, we observe not only a decrease in the number of metal particles but also a decrease in the surface area to volume ratio. Some of the metal that diffuses away from particles on the oxide support can be regenerated and reappears back on the catalyst support surface under reducing conditions. These observations provide insight on how rapid cycling between oxidative and reductive catalytic operating conditions affects catalyst structure.

Approaches to synthesize MgO nanostructures for diverse applications

Magnesium oxide remained interesting from long time for several important phenomena like; defect induced magnetism, spin electron reflectivity, broad laser emission etc. Moreover, nanostructures of this material exhibited suitability for different kinds of applications ranging from wastewater treatment to spintronics depending upon their shape and size. In this way, researchers had grown nanostructures in the form of nanoparticles, thin films, nanotubes, nanowalls, nanobelts. Though nanoparticles and thin films are well known form of nanostructures and wide variety of synthesis approaches are available, however, limited methodology for other nanostructures are available. In order to grow these nanostructures in an optimized way an understanding of these methods is essential. Thus, this review article depicts an overview of various approaches for design of different kinds of nanostructures.

Influence of supporting amorphous carbon film thickness on measured strain variation within a nanoparticle

Strain variation within a nanoparticle plays a crucial role in tuning its properties. High Resolution Transmission Electron Microscopy (HRTEM) images of a nanoparticle supported on amorphous carbon film are used to determine the strain variation. Experimental measurements in this present study on a single crystalline silver nanoparticle exhibited an unexpected high strain variation. Generally, the influence of carbon film is not accounted for during interpretation of measured strain variation. However, experimental observations raise the question whether the supporting carbon film alters the measured strain variation. In order to address this, strain variation within a simulated Ag nanoparticle supported on an amorphous carbon is measured with varying film thicknesses. The results show that supporting carbon film thickness introduces an artefact leading to more strain variation than what is present within an unsupported nanoparticle. Moreover, the variation increases with increasing supporting carbon film thickness. This effect is more pronounced in a thinner nanoparticle. Without considering this influence, the interpretation of strain within a nanoparticle may introduce severe errors which in turn will affect the tunability of desirable properties for different applications. Since strain measurement depends on the accuracy of the atomic position, the interpretation of any result using the atomic position from HRTEM images of a nanoparticle should consider the influence of supporting film.