Improving Photocatalytic Degradation Activity of Organic Pollutant by Sn(4+) Doping of Anatase TiO(2) Hierarchical Nanospheres with Dominant {001} Facets

Herein, high-energy {001} facets and Sn(4+) doping have been demonstrated to be effective strategies to improve the surface characteristics, photon absorption, and charge transport of TiO(2) hierarchical nanospheres, thereby improving their photocatalytic performance. The TiO(2) hierarchical nanospheres under different reaction times were prepared by solvothermal method. The TiO(2) hierarchical nanospheres (24 h) expose the largest area of {001} facets, which is conducive to increase the density of surface active sites to degrade the adsorbed methylene blue (MB), enhance light scattering ability to absorb more incident photons, and finally, improve photocatalytic activity. Furthermore, the Sn(x)Ti(1−x)O(2) (STO) hierarchical nanospheres are fabricated by Sn(4+) doping, in which the Sn(4+) doping energy level and surface hydroxyl group are beneficial to broaden the light absorption range, promote the generation of charge carriers, and retard the recombination of electron–hole pairs, thereby increasing the probability of charge carriers participating in photocatalytic reactions. Compared with TiO(2) hierarchical nanospheres (24 h), the STO hierarchical nanospheres with 5% n(Sn)/n(Ti) molar ratio exhibit a 1.84-fold improvement in photodegradation of MB arising from the enhanced light absorption ability, increased number of photogenerated electron–hole pairs, and prolonged charge carrier lifetime. In addition, the detailed mechanisms are also discussed in the present paper.