Fabrication of three-dimensional hollow nanocassette photocatalysts RE-TiO2 (RE = La, Ce, Sm, Yb, and Tm) with enhanced pesticide degradation activity and highly exposed (101) crystal planes

In this study, using a solvothermal technique, we created several rare earth element-doped TiO2 hollow nanobox catalysts. A variety of characterization techniques were used to examine the basic physicochemical features of the synthesized samples. The results reveal that rare earth element can be preferentially incorporated into the unit cells of TiO2 hollow nanoboxes and replace titanium atoms, leading to an increase in the electron transfer rate and an extension of the light absorption of hollow-structured TiO2 from the UV to the visible region. Meanwhile, rare earth element doping promotes the reaction of electrons clustered in the highly exposed (101) crystal plane with chemisorbed oxygen to generate superoxide radicals, thereby improving photocatalytic degradation activity. In the activity test, the Tm-TiO2 samples showed the greatest photocatalytic degradation activity among others. And the degradation rate reached more than 90% under ultraviolet light in 90 min. Furthermore, DFT calculations indicate that the band gap of TiO2 (001) is lower than that of TiO2 (101). This suggests that the (001) crystal plane is more easily excited, and photogenerated electron-hole separation occurs. Moreover, the separated electrons transfer to the (101) crystal plane, effectively inhibiting electron-hole recombination.