Preparation of PbBiO2I ultrathin nanosheets with rich oxygen vacancies for enhanced visible-light-driven photocatalytic activities

Photocatalytic oxidation technology is deemed as a prospective approach to settle the global environmental crisis. Nevertheless, the photocatalytic performance is limited by the insufficient solar light harvesting ability and disappointing charge carrier separation efficiency of photocatalysts. Herein, PbBiO2I ultrathin nanosheets with tunable oxygen vacancy (OV) concentrations were successfully fabricated via ionothermal process. The crystal structure, morphology and photoelectrochemical properties of the acquired catalysts were systematically studied. The photocatalytic degradation results demonstrate that rich oxygen vacancy (ROV) PbBiO2I possesses the highest photocatalytic degradation activity, which is about 2.9 and 35.0 times higher than those of deficient oxygen vacancy (DOV) PbBiO2I and bulk PbBiO2I in rhodamine B (RhB) degradation. The enhanced visible-light absorption region arising from bulk oxygen vacancy and surface oxygen vacancy can serve as highly active sites for catalytic reaction. This contributes to enriching electrons to accelerate oxygen molecular activation and boost charge separation. Additionally, superoxide radicals (O2 center dot-) and holes (h+) are proved to be the major reactive species during photocatalytic process. By which, a feasible photocatalytic mechanism was primarily proposed. This research can offer a new avenue for developing bismuth-based defective photocatalyst in the field of environmental remediation.