Oxygen vacancies and OH species in rutile and anatase TiO2 polymorphs

Oxide/polymer interfaces for hybrid and organic solar cells: Anatase vs. Rutile TiO2

“…The presence of FTO and TiO 2 -rutile could be behind the better photovoltaic behavior observed for the devices under an N 2 . Under inert atmospheres, and independently of the crystalline TiO 2 phase, the release of oxygen from its structure produces oxygen vacancies (O vac ) on TiO 2 [20], becoming highly conductive [21][22][23][24]. Higher amount of O vac can be formed in anatase in comparison with rutile (this is the reason why anatase shows higher conductivity and better photocatalytic properties [22,24,25]).…”

“…Under inert atmospheres, and independently of the crystalline TiO 2 phase, the release of oxygen from its structure produces oxygen vacancies (O vac ) on TiO 2 [20], becoming highly conductive [21][22][23][24]. Higher amount of O vac can be formed in anatase in comparison with rutile (this is the reason why anatase shows higher conductivity and better photocatalytic properties [22,24,25]). Since O vac are known as good electron traps [26,27], higher amount of recombination centers can be expected in anatase in comparison with rutile-based devices.…”

“…For a photovoltaic device, the presence of O vac is undesirable, since O vac act as electron traps and the final oxide is full of recombination centers [26,27]. Thus, low or null photovoltaic response would be expected for a device applying doped oxides, especially in an oxygen-free environment, where the conductivity of the doped oxide increases and high amount of O vac are formed [20][21][22][23][24]. The question is then, why the Nb-TiO 2 /polymer solar cell, reported in our previous work [6], shows photovoltaic response and longer stability than the bare TiO 2 when working under inert atmospheres?…”

Photocatalytic degradation of phenolic compounds with new TiO2 catalysts

“…These groups are located at defects and/or oxygen vacancies on the surface [45]. That is, cata- lysts calcinated at higher temperature have fewer defects and e − /h + recombination rate will also be lower which should favour the formation of radicals.…”

A DFT-based Analysis on H2O Molecule Adsorption and Dissociation on the Rutile TiO2 (110) and (100) Surfaces

“…The use of hybrid functionals and DFT＋U calculations were carried out to address these deˆciencies. Studies on oxygen deˆcient TiO 2 using hybrid functionals and DFT＋U calculations [35][36][37][38][39] indeed showed excess electron localization around Ti atom, either on the surface and/or the subsurface with varying results depending on usage hybrid functional and the choice of U parameter employed in the DFT＋U calculations. However, some STM and PED studies on the distribution of excess electrons points to electron delocalization consistent with DFT results 40,41) .…”