Boosting light harvesting and charge separation over hollow double-shelled Ag@SrTiO3-TiO2 with Z-scheme heterostructure for highly efficient photocatalytic reduction of nitrate to N2

Hollow double-shelled [email protected]3-TiO2 with Z-scheme heterostructure was constructed for highly efficient photocatalytic reduction of nitrate to N2. 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 SrTiO3 to Ag0 caused by electron sink effect were utilized to reduce nitrate, while photo-generated electrons of TiO2 migrated to SrTiO3 via transport bridge of Ti3+ 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 CO2− played important role in photocatalytic denitrification. Furthermore, Ag0 acted as co-catalyst which not only promoted photogenerated electrons transfer to nitrate but also enhanced nitrate conversion selectivity to N2. 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.