Enhancement of the photocatalytic response of Cu-doped TiO2 nanotubes induced by the addition of strontium

The Role of the Ferroelectric Polarization in the Enhancement of the Photocatalytic Response of Copper-Doped Graphene Oxide–TiO2 Nanotubes through the Addition of Strontium

“…This general decrease in intensity is however not associated with changes in the respective contributions of the different emission peaks. This result agrees with previous observations on GO-free Sr-Cu-TiNT materials showing a lower tendency for recombination either in the bulk or with surface oxygen vacancies. Therefore, the addition of strontium up to 0.8 wt % leads undoubtedly to a lower propensity for recombination.…”

“…A deeper analysis of the main E 1g vibration mode reveals some significant shifts with increasing Sr loading with blue and red shifts observed at Sr content similar to that in our previous study on GO-free Sr-Cu-TiNT solids . In this respect, the addition of 0.2 wt % Sr leads to a blue shift of the main E 1g vibration mode from 145.3 to 145.8 cm –1 .…”

“…The red shift can then be attributed to the formation of a new phase (SrTiO 3 or SrO) on the surface of the TiO 2 nanotubes. The creation of surface oxygen vacancies at a very low loading in strontium of 0.2 wt % results from a strong initial interaction between strontium and titania inducing the creation of SrTiO 3 entities on the semiconductor surface as already observed on GO-free Sr-Cu-TiNT solids . The similar shift variations observed here at a given Sr loading whatever the presence of GO reflect the absence of perturbation coming from graphene oxide and susceptible to influencing the Sr-TiO 2 interaction.…”

“…However, this conclusion was only reached indirectly by default without evidencing clearly the link between polarization and enhanced photocatalytic activity. More recently, Alrashedi et al . showed that the addition of low amounts of strontium onto 0.5 wt % Cu-doped TiO 2 nanotubes (Sr-0.5Cu-TiNT) enhances the photocatalytic degradation of formic acid under UV irradiation.…”

“…However, this conclusion was only reached indirectly by default without evidencing clearly the link between polarization and enhanced photocatalytic activity. More recently, Alrashedi et al 55 showed that the addition of low amounts of strontium onto 0.5 wt % Cu-doped TiO 2 nanotubes (Sr-0.5Cu-TiNT) enhances the photocatalytic degradation of formic acid under UV irradiation. The determination of dielectric properties of Sr-0.5Cu-TiNT strongly emphasizes that an optimum formation of in situ SrTiO 3 at the surface of TiO 2 nanotubes helps to stabilize photogenerated charges at the semiconductor surface through in situ polarization effects induced by the ferroelectric domains of the adjacent SrTiO 3 species.…”