Fabrication of β-phase AgI and BiO co-decorated BiOCO heterojunctions with enhanced photocatalytic performance.

BiOCO was co-decorated by β-phase AgI and BiO forming visible-light-active AgI(β)/BiO(β)-BiOCO composite via simply calcining AgI/BiOCO. The calcination temperature and time played vital role in regulating the structure as well as photocatalytic performance. Optimal AgI(β)/BiO(β)-BiOCO was obtained after 325 C calcination for 2 h with 5% AgI. The ratio of BiO to BiOCO was estimated to be ca. 3:1 on the catalyst surface. The transformation process for n-type BiOCO to p-type BiO(β) was monitored and verified by flat band potential measurements. Due to the presence of p-n junctions between p-type BiO(β), n-type AgI(β) and BiOCO, the optimized ternary composite displayed enhanced photocurrent density and reduced charge transfer resistance, which were beneficial for photocatalytic applications. Despite of decreased specific surface area, dramatically enhanced photocatalytic performance can be observed for simultaneous removal of Cr(VI) and phenol. For example, the estimated k and k on AgI(β)/BiO(β)-BiOCO were 3.3 and 2.2 times relative to those on uncalcined AgI/BiOCO, respectively. The optimized composite also displayed good stability in 4 successive cyclic runs.