Generation of VBr•VBi"′VO•• defect clusters for 1O2 production for molecular oxygen activation in photocatalysis

Defect engineering on a semiconductor surface can provide coordinatively unsaturated sites for molecular oxygen activation in photocatalysis. In this work, we demonstrated that the vacancy type was key to modulate the molecular oxygen activation process on BiOBr nanosheets. By regulating the reaction time, an oxygen vacancy (V-O(center dot center dot)), a double atom defect cluster (V ''' V-Bi(O)center dot center dot) and triple atom clusters V '''(BiVOV)-V-center dot center dot '''(Bi) and (VBrV)-V-center dot ''' V-Bi(O)center dot center dot) were accordingly generated on the surface, subsurface and bulk of BiOBr. More importantly, the newly-discovered (VBrV)-V-center dot ''' V-Bi(O)center dot center dot defect cluster was highly related to the singlet oxygen (O-1(2)) production ability of BiOBr. Meanwhile, the excellent photocatalytic selective oxidation reactions were successfully realized over BiOBr with the (VBrV)-V-center dot ''' V-Bi(O)center dot center dot defect cluster. In addition, time-dependent defect cluster generation and the associated molecular oxygen activation were discussed.