Effect of nitridation on visible light photocatalytic behavior of microporous (Ag, Ag2O) co-loaded TiO2

A simple solvothermal approach with post-calcination is used to obtain (Ag, Ag 2 O) co-loaded TiO 2 microspheres with high specific surface area (43.8 m 2 g -1 ) and desirable visible light photocatalytic degradation (64% after 2 h visible light irradiation). Generally, N-doping of TiO 2 via nitridation using NH 3 improves the visible light absorption property of material. However, nitridation of (Ag, Ag 2 O) co-loaded TiO 2 results in a deleterious impact on the photocatalytic performance (around 20% after 2 h visible light irradiation). This is because nitridation of Ag-Ag 2 O-TiO 2 results in (a) reduction of Ag 2 O to Ag and (b) Ag agglomeration and grain growth on TiO 2 particles. These results in fact imply that in as-synthesized (Ag, Ag 2 O) co-loaded TiO 2 systems, local surface plasmonic resonance (associated with of 5–12 nm Ag particles) aids in enhanced broad band visible light absorption; furthermore the heterojunction between TiO 2 and Ag 2 O improves efficiency with which photogenerated carriers become available for photocatalysis . In all cases we show through selective radical quenching experiments that singlet oxygen is the primary reason for the dye degradation observed.