TiO2/S-Doped Carbons Hybrids: Analysis of Their Interfacial and Surface Features

Abstract

Hybrids containing approximately equal amounts of P25 TiO2 and S-doped porous carbons were prepared using a water-based slurry mixing method. The materials were extensively characterized by adsorption of nitrogen, potentiometric titration, thermal analysis in air and in helium, XRD, XPS and SEM. The collected results showed the significant blockage of carbon micropores by TiO2 particles deposited on their outer surface. The formation of a new interface, especially for the S-rich samples, might also contribute to the porosity alteration. Analysis of surface chemistry suggested the presence of Ti-S bonds with an involvement of sulfur from thiophenic species in the carbon phase. The latter, especially when polymer-derived, was mainly deposited on the TiO2 nanoparticles. Formation of Ti-S stabilized sulfur and increased the ignition temperature of the hybrids, especially those with a high content of sulfur, in comparison with the ignition temperature of carbons. The surfaces of hybrid with S-containing carbons was also thermally very stable and of basic chemical nature. The formation of interfacial structures Ti-C was detected by XPS analysis suggesting a partial reduction of the Ti.

Analyzing the surface of functional nanomaterials—how to quantify the total and derivatizable number of functional groups and ligands

“…Potentiometric titrations have been used for characterizing the surface chemistry of different types of organic and inorganic NM with various FG, and have been applied to determine the number and nature of acidic sites (carboxy, lactone, phenol, and ester groups) on carbonbased materials like carbon dots (CD), nanocellulose/ nanobentonite composites, biochar particles, multi-walled carbon nanotubes, or cellulose nanocrystals [76][77][78][79][80], or to quantify hydroxy (silanol) and thiol groups on hybrid silica particles [81]. Potentiometric titrations have also been used to determine the total number of acidic sites on different catalyst materials like phosphotungstic acid-functionalized Sn-TiO 2 and organic-inorganic polyoxometalate NP, SrTiO 3 particles used to catalyze condensation, hydrogenation, and amination reactions, functionalized silica particles employed as catalysts for the esterification of linoleic acid, and photocatalytic TiO 2 / S-doped carbon hybrids [82][83][84][85][86]. For example, Wang et al potentiometrically quantified carboxy and amino groups on fluorescent CD prepared with different amounts of L-arginine or L-glycine (see Fig.…”

Síntesis y caracterización de materiales basados en TiO<SUB>2</SUB> y g-C<SUB>3</SUB>N<SUB>4</SUB> inmovilizado en carbón activado para la eliminación de contaminantes de origen farmacéutico

“…Smith et al, 2016). En el caso del espectro XPS para O1s fue asignado a cuatro componentes asociadas a grupos: carboxilo O=C alrededor 532,3 eV, O-C entre 532,7 y 533,1 eV atribuido al grupo fenol, así como un pico intenso a 531,08 eV asociado al oxígeno en TiO2/W-O y la señal a 534,5 eV asociada a oxígeno quimisorbido (Bandosz et al, 2019;Bedia et al, 2018;Ochoa Rodríguez et al, 2021) A partir de la caracterización realizada a los materiales híbridos permite inferir que el carbón activado y el TiO2-TPA lograron integrarse exitosamente lo que le otorgaría a los materiales propiedades mejoradas para la fotodegradación de fármacos disueltos en agua debido a: i.) que el carbón activado puede funcionar como aceptor de los electrones de la banda de conducción fotogenerados en el semiconductor, lo que reduciría la recombinación del par e-/h+, mediante la separación de los portadores de carga a través de la deslocalización y estabilización de los electrones en las capas grafíticas de la matriz carbonosa (Velasco y Maurino y Laurenti y Fonseca y et al, 2013); ii.)…”