TiO 2 has been regarded as an efficient benchmark photocatalyst that can work under ultraviolet light. However, further modification of TiO 2 for achieving even higher photocatalytic activities is necessary for practical applications and for enriching the family of TiO 2 -based photocatalysts. Herein, a novel Ag-SrTiO 3 /TiO 2 photocatalyst was prepared by hydrothermally treating TiO 2 nanosheets in an aqueous Sr(OH) 2 solution (to form SrTiO 3 nanocubes supported on TiO 2 nanosheets) followed by depositing Ag nanoparticles via photoreduction in the presence of an aqueous AgNO 3 solution. In this case, Ag nanoparticles were found to be deposited on both SrTiO 3 and TiO 2 surfaces. The resulting Ag-SrTiO 3 /TiO 2 was found to be more active than reference catalysts such as TiO 2 , SrTiO 3 /TiO 2 , Ag/TiO 2 , and Ag/SrTiO 3 in photocatalytic degradation of rhodamine B (RhB) and ciprofloxacin hydrochloride (CIP) under simulated sun light. Relevant catalysts were characterized systematically, and possible reasons for the enhanced activity of Ag-SrTiO 3 /TiO 2 was explained.
Hollow double-shelled Ag@SrTiO 3 -TiO 2 with Z-scheme heterostructure was constructed for highly efficient photocatalytic reduction of nitrate to N 2 . The 3D finite-difference-time-domain analysis indicated that hollow double-shelled structure improved light harvesting due to multiple reflections. Photo-generated electrons transfer from SrTiO 3 to Ag 0 caused by electron sink effect were utilized to reduce nitrate, while photo-generated electrons of TiO 2 migrated to SrTiO 3 via transport bridge of Ti 3+ defects for electron–hole recombination. Such charge carriers migration pathway facilitated the construction of Z-scheme heterostructure, which enhanced charge separation yet still retained high redox powers. Both photogenerated electrons and CO 2 − played important role in photocatalytic denitrification. Furthermore, Ag 0 acted as co-catalyst which not only promoted photogenerated electrons transfer to nitrate but also enhanced nitrate conversion selectivity to N 2 . Combining the above advantages, nitrate removal rate and the nitrogen selectivity reached 97.2 % and 98.8 % within 60 min, respectively. Even after five cycles, it still remained satisfied photocatalytic activity and stability. In summary, this work proposed a feasible strategy to construct Z-scheme hollow double-shelled photocatalyst for efficient photocatalytic denitrification.
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