Optical properties of sol-gel materials doped with ethyl 2-(7-hydroxy-2-oxo-2H-chromen-4-yl) acetate

Transparent sol-gel glassy monoliths doped with coumarin molecules [ethyl 2-(7-hydroxy-2-oxo-2H-chromen-4-yl) acetate] displaying a strong blue luminescence are characterized by optical spectroscopy, X-Ray diffraction, SEM and TG/FT-IR spectroscopy. The UV/Vis, luminescence and excitation spectra of the doped sol-gel materials and of ethanol solutions of coumarin are discussed. The coumarin optical spectra are used as a probe for incorporation in the gel structure

Luminescence of Binary-Doped Silica Aerogel Powders: A Two-Step Sol-Gel Approach

In this study, we report a novel synthesis of hydrophobic silica aerogel powder composites, functionalized and binary-doped with [Tb(phen)2](NO3)3 and [Eu(phen)2](NO3)3 nanocrystals, employing a two-step sol-gel methodology. The investigation delves into the structural elucidation, optical properties and thermal conductivity of these functionalized Tb(III)-Eu(III) composites. Our analysis includes diffuse reflectance spectra and excitation and luminescence spectra, highlighting the quantum yields of composites with varying chemical compositions. Remarkably, these samples exhibit a strong luminescence, with distinct hues of red or green based on the specific doping type and level. The detailed examination of excitation spectra and quantum yields establishes robust energy-transfer mechanisms from the 1,10-phenanthroline molecule to the lanthanide ions. Notably, our study uncovers a Tb3⁺→Eu3⁺ energy-transfer phenomenon within the binary functionalized samples, providing compelling evidence for a structural formation process occurring within the mesoporous framework of the aerogel powders

Transport of Carbon Dioxide through a Biomimetic Membrane

Biomimetic membranes (BMM) based on polymer filters impregnated with lipids or their analogues are widely applied in numerous areas of physics, biology, and medicine. In this paper we report the design and testing of an electrochemical system, which allows the investigation of CO2 transport through natural membranes such as alveoli barrier membrane system and also can be applied for solid-state measurements. The experimental setup comprises a specially designed two-compartment cell with BMM connected with an electrochemical workstation placed in a Faraday cage, two PH meters, and a nondispersive infrared gas analyzer. We prove, experimentally, that the CO2 transport through the natural membranes under different conditions depends on pH and displays a similar behavior as natural membranes. The influence of different drugs on the CO2 transport process through such membranes is discussed

The Influence of the Precursor’s Nature and Drying Conditions on the Structure, Morphology, and Thermal Properties of TiO2 Aerogels

A cost-effective solution for the synthesis of high-porosity TiO2 aerogels, which can be used as a mesoporous perovskite network charge-carrier material during the manufacture of solar cells, is described. The effects of the synthesis parameters (precursor (titanium (IV) isopropoxide (TIP) and tetrabutyl orthotitanate (TBOT)), additional solvent exchange (n-hexane (nH), cyclohexane (CH), and diethyl ether (DE)), subcritical drying (800 mbar vacuum, 70 °C, 8 h), aging, and calcination on the aerogel’s structure have been investigated. Methods of XRD, FT-IR, BET, Raman, STA, SEM, UV–vis, and thermal conductivity measurements were applied to find out the relation between the synthesis conditions and the properties of the synthesized aerogels. Amorphous aerogels are polydispersed systems with the highest probability of pore diameter from 0.5 to 15 nm. An nH-exchanged, aged aerogel synthesized from the precursor TIP shows the highest diameter of pores. After calcination, the aerogels tend to crystallize into an anatase phase and the size of the crystallites depends on the precursor’s nature. Calcination leads to a significant increase in both the apparent and true density of the aerogels, and it also results in an increase in porosity and thermal conductivity