A comparative study of self-doped TiO2 catalysts obtained from different routes: analysis of efficiencies in the degradation of 2-chlorophenol under LED visible light

Abstract

Titanium dioxide photocatalysts were synthesized through two different routes. One catalyst was obtained by a conventional sol–gel method without surfactants, while the other was prepared from the calcination of a nitrogen-functionalized metal–organic framework (MOF) precursor that involves the use of organic ligands and solvents. In both cases, the carbon and nitrogen species present in the final oxides originated from the organic precursors used during synthesis, leading to self-doped TiO₂ materials. The effect of these thermally induced doping species was investigated. The resulting materials exhibited mesoporosity and an anatase crystalline phase. After 120 min of reaction under visible LED irradiation, 91% degradation of 2-chlorophenol was achieved with the sol–gel catalyst and 64% with the MOF-derived one, corresponding to a higher photonic efficiency for the former. The improved activity is attributed to the coexistence of interstitial and substitutional carbon species within its structure, whereas only interstitial carbon and a small amount of nitrogen were detected in the MOF-derived catalyst. Owing to its higher efficiency and greener synthesis route, the sol–gel derived catalyst represents a promising alternative for sustainable photocatalytic applications.