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 Ag@SrTiO3-TiO2 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 SrTiO3 to Ag-0 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 center dot- played important role in photocatalytic denitrification. Furthermore, Ag-0 acted as co-catalyst which not only promoted photo -generated 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.