Tailoring the visible light photoactivity of un-doped defective TiO2 anatase nanoparticles through a simple two-step solvothermal process

[EN] Anatase TiO2 has become a material of great interest for photocatalytic production of hydrogen, environmental purification and solar energy conversion. Among the key parameters boosting the photocatalytic efficiency of the anatase nanoparticles, an increased light absorption to expand its optical response to the visible region, together with an improved charge separation of the photo- generated electrons and holes, can be enumerated. In this work, yellow-coloured, single-phase anatase nanoparticles have been obtained using a simple two-step solvothermal routine which requires no external addition of dopants, nor the use of a harassing/aggressive synthesis atmosphere. The obtained powders display a lowered bandgap (<3.0 eV) and significantly reduce the recombination processes, eventually leading to an improved photocatalytic performance under visible light, as exemplified by an enhanced degradation of phenol. This exceptional response is linked to the presence of intrinsic defects in the yellowish particles and, hence, the specific conditions of the proposed methodology become crucial to produce a propitious TiO2-defective nanomaterial capable of photo-degrade the phenol molecule, in contrast with the lack of photocatalytic activity currently exhibited by commercial photocatalysts under visible light.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through MAT2014-59210-JIN, MAT2016-80182-R, MAT2016-80394-R and CSIC 201760E012 projects. Dr T Jardiel acknowledges the European Science Foundation (ESF) and the Ramon y Cajal Program of MICINN for the financial support. Dr D G Calatayud also acknowledges the Fundación General CSIC (ComFuturo Program) for the financial support