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

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.