High-Gravity-Assisted Synthesis of Surfactant-Free Transparent Dispersions of Monodispersed MgAl-LDH Nanoparticles

Controllable synthesis of layered double hydroxide nanosheets to build organic inhibitor-loaded nanocontainers for enhanced corrosion protection of carbon steel

The development of layered double hydroxide (LDH) nanosheets as nanocontainers has been intensively studied in recent years. Despite their potential for application on a large scale, their synthesis in an aqueous medium is rarely reported. Herein, we report a straightforward approach for the controllable synthesis of uniform MgAl-LDH nanosheets by an aqueous nucleation process followed by a hydrothermal treatment. The key to this method relies on the well-dispersed LDH nuclei that are produced by high-speed homogenization. Following the nucleation step, the coalescence of the aggregate hydroxide layers is diminished by hydraulic shear forces, leading to the disaggregation and even distribution of LDH nuclei. As a result, the oriented growth of individual crystals along the horizontal plane becomes predominant, leading to a high surface charge density of the hydroxide sheets and preventing their stacking. The electron microscope virtual proofs showed that the particles had a well-defined circular shape with a thickness of about 2-3 nm. Afterward, for the first time, LDH nanosheets were used to prepare LDH nanocontainers loaded with 2-benzothiazolythio-succinic acid (BTSA) by anion exchange. The incorporation of BTSA into the interlayer region and the emission behavior of the inhibitor were investigated. These results indicate that the prepared nanosheets can be utilized as effective nanocontainers for organic inhibitor loading and anti-corrosion application.

Intrabasal Plane Defect Formation in NiFe Layered Double Hydroxides Enabling Efficient Electrochemical Water Oxidation

Defect engineering has proven to be one of the most effective approaches for the design of high-performance electrocatalysts. Current methods to create defects typically follow a top-down strategy, cutting down the pristine materials into fragmented pieces with surface defects yet also heavily destroying the framework of materials that imposes restrictions on the further improvements in catalytic activity. Herein, we describe a bottom-up strategy to prepare free-standing NiFe layered double hydroxide (LDH) nanoplatelets with abundant internal defects by controlling their growth behavior in acidic conditions. Our best-performing nanoplatelets exhibited the lowest overpotential of 241 mV and the lowest Tafel slope of 43 mV/dec for the oxygen evolution reaction (OER) process, superior to the pristine LDHs and other reference cation-defective LDHs obtained by traditional etching methods. Using both material characterization and density functional theory (DFT) simulation has enabled us to develop relationships between the structure and electrochemical properties of these catalysts, suggesting that the enhanced electrocatalytic activity of nanoplatelets mainly results from their defect-abundant structure and stable layered framework with enhanced exposure of the (001) surface.

Controllable Synthesis of Hollow Silica Nanoparticles Using Layered Double Hydroxide Templates and Application for Thermal Insulation Coating

The innovative hollow silica nanoparticle (HSN) material possesses substantial potential for application in the insulation field. The size and shell thickness of HSN are crucial factors in determining their inherent properties, which, in turn, impact their applicability. This research presents a facile approach to synthesizing HSN in which sodium silicate (Na2SiO3) was utilized as the silica precursor that can be directly deposited onto layered double hydroxide (LDH) nanoparticles without the utilization of any surfactant. A subsequent acid treatment was used to eliminate the templates, resulting in the formation of an HSN devoid of mesopores in silica shells. By utilizing various sizes of LDH cores, obtainable via coprecipitation followed by hydrothermal treatment, we were capable of successfully synthesizing the hollow particles with adjustable diameters ranging from 50 to 200 nm. In addition, the shell thickness is varied from 6.8 to 22.5 nm by varying the silicate solution concentration. Results demonstrate that prepared HSNs have low thermal conductivity and high reflectance in the UV-vis-NIR range (averaging 82.1%). These findings suggest that HSN can be utilized as an effective inorganic filler in the formulation of reflective and thermally insulating coatings.

Flexible Methyl Cellulose/Polyaniline/Silver Composite Films with Enhanced Linear and Nonlinear Optical Properties

In order to potentiate implementations in optical energy applications, flexible polymer composite films comprising methyl cellulose (MC), polyaniline (PANI) and silver nanoparticles (AgNPs) were successfully fabricated through a cast preparation method. The composite structure of the fabricated film was confirmed by X-ray diffraction and infrared spectroscopy, indicating a successful incorporation of AgNPs into the MC/PANI blend. The scanning electron microscope (SEM) images have indicated a homogenous loading and dispersion of AgNPs into the MC/PANI blend. The optical parameters such as band gap (Eg), absorption edge (Ed), number of carbon cluster (N) and Urbach energy (Eu) of pure MC polymer, MC/PANI blend and MC/PANI/Ag films were determined using the UV optical absorbance. The effects of AgNPs and PANI on MC polymer linear optical (LO) and nonlinear optical (NLO) parameters including reflection extinction coefficient, refractive index, dielectric constant, nonlinear refractive index, and nonlinear susceptibility are studied. The results showed a decrease in the band gap of MC/PANI/AgNPs compared to the pure MC film. Meanwhile, the estimated carbon cluster number enhanced with the incorporation of the AgNPs. The inclusion of AgNPs and PANI has enhanced the optical properties of the MC polymer, providing a new composite suitable for energy conversion systems, solar cells, biosensors, and nonlinear optical applications.