Fabrication of a novel BiOI/KTaO(3) p–n heterostructure with enhanced photocatalytic performance under visible-light irradiation

In this study, a series of BiOI/KTaO(3) p–n heterojunctions were prepared via a facile in situ chemical bath strategy. The photocatalytic properties of the catalysts was tested by the degradation of Rhodamine B (RhB) and phenol under visible light irradiation. The BiOI/KTaO(3) composites exhibited improved photocatalytic efficiency compared to the individual catalysts. In particular, 54 wt% BiOI/KTaO(3) displayed the highest photocatalytic activity since it degraded 98.6% RhB within 30 minutes, while only 68.1% RhB was degraded over pure BiOI under identical conditions. In addition, the reaction kinetic constant of RhB degradation over 54 wt% BiOI/KTaO(3) was approximately 2.56 and 115-fold larger than those of pure BiOI and KTaO(3,) respectively. The results of PL, photocurrent and EIS indicated that the improved photocatalytic efficiency could root in the p–n junction formed between BiOI and KTaO(3), which was conducive to the separation and migration of photo-generated carriers. Furthermore, a free-radical capture experiment illustrated that h(+) and ˙O(2)(−) were the key factors in the photodegradation of RhB.