Study on the performance and mechanism of a p–n type In2O3/BiOCl heterojunction prepared using a sacrificial MOF framework for the degradation of PFOA

Abstract

In this study, an In₂O₃/BiOCl p–n heterojunction was prepared using a co-calcination method. By utilising the built-in electric field formed near the heterojunction interface, photoinduced electron–hole pairs can be effectively separated, thereby enhancing the photocatalytic activity of the photocatalyst. Experimental results indicate that the p–n heterojunction photocatalyst significantly enhanced photocatalytic activity in the degradation of PFOA under UV light irradiation. Within 2 h, the defluorination rate of PFOA achieved by the heterojunction photocatalyst reached 84.01%, while the pure BiOCl and In₂O₃ photocatalysts exhibit defluorination rates of 61.82% and 56.69%, respectively. The degradation mechanism of PFOA was studied through free radical capture experiments, VB-XPS, FT-IR, and LC-MS. Mechanistic studies show that the main active substances in the heterojunction are holes (h⁺) and superoxide radicals (˙O₂⁻). The holes in the valence band of In₂O₃ are transferred to BiOCl under the effect of the built-in electric field, and the defluorination of PFOA mainly occurs on the BiOCl component of the heterojunction. This highlights the superiority of heterojunctions over pure photocatalysts in terms of their photocatalytic efficiency and provides insights into the photocatalytic degradation mechanism of PFOA.