Fabrication of a novel BiOI/KTaO3 p–n heterostructure with enhanced photocatalytic performance under visible-light irradiation

Abstract

In this study, a series of BiOI/KTaO₃ 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/KTaO₃ composites exhibited improved photocatalytic efficiency compared to the individual catalysts. In particular, 54 wt% BiOI/KTaO₃ 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/KTaO₃ 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 KTaO₃, which was conducive to the separation and migration of photo-generated carriers. Furthermore, a free-radical capture experiment illustrated that h⁺ and ˙O₂⁻ were the key factors in the photodegradation of RhB.