Novel p-n type porous Ag2O/Bi5O7I heterojunction for Uv–Vis-NIR activated high efficient photocatalytic degradation of bisphenol A: Photoelectric properties and degradation mechanism

Abstract

Exploring effective strategies to strengthen the photoresponse and charge separation efficiency is crucial for the preparation of photocatalysts with superior-performance. Herein, series of 0D-2D Ag2O/Bi5O7I heterojunctions with UV–Vis-NIR spectrum response were prepared by modifying Ag2O on the surface of porous Bi5O7I nanosheets to boost the photocatalytic degradation of bisphenol A. The modified p-type Ag2O semiconductor not only extends the optical absorbance range of the prepared p-n heterojunction but also improves the separation efficiency of photoinduced charge carriers by the internal electric field. Moreover, the unique porous thin-layer structure can further shorten the transport distance of bulk charges to the surface. In addition, uniformly distributed holes are able to provide more active sites to accelerate charge depletion on Bi5O7I substrate. As a result, the interfacial coulomb electrostatic repulsive force was greatly weakened, making it easier for the charge transferences from Ag2O to Bi5O7I under the internal electric field. Therefore, the prepared p-n heterojunction exhibited excellent performance in photocatalytic degradation of bisphenol A. In particular, 25% Ag2O/Bi5O7I showed the best bisphenol A degradation performance, which was 7.23 and 4.39 times than that of pristine Ag2O and Bi5O7I, respectively. In addition, the prepared samples showed excellent photocorrosion resistance, due to the rapid consumption of enriched electrons by the porous structure. Furthermore, intermediates of bisphenol A degradation reaction were characterized by liquid mass method, and then the degradation pathway was deduced. This work is of significance to the construction and design of efficient photocatalysts with full spectral response and high photoelectric conversion efficiency.