Multisite luminescence and photocatalytic properties of TiO2:Sm3+ and TiO2:Sm3+@TiO2/TiO2:Sm3+@SiO2 luminescent enhancement materials

Sm3+ doped TiO2 nanocrystals with various morphologies were fabricated via a facile hydrothermal route, and the effect of morphology on the luminescence properties and photocatalytic activity of the products has been investigated. PL studies on TiO2:Sm3+ revealed that the sensitized emission is a much more efficient pathway than the direct excitations of Sm3+. Combined 10 K spectra and theoretical analysis, several kinds of sites of Sm3+ ions have been found in TiO2 matrix. Most importantly, structural models for the formation of multiple sites are proposed based on the optical behaviors of Sm3+ at different sites. Photocatalytic results suggest that flower-like hierarchical architectures show the highest photocatalytic activity compared with nanorods samples with different aspect ratios, and the photodegradation efficiency was 96.8% after 20 min for degradation of methyl orange under white light irradiation. And surface photovoltage spectroscopy (SPV) have been measured to understand the separation and transfer behaviour of photogenerated charges which are helpful for explaining the photocatalytic and luminescence properties deeply. Moreover, TiO2:Sm3+@TiO2 luminescent enhancement homo-structures and TiO2:Sm3+@SiO2 luminescent enhancement hetero-structures are prepared. The effect of calcination temperature on luminescence intensity and the luminescence enhancement mechanism have been discussed in detail.