Dual functional photocatalysts of echinoid-like Bi2S3@ZnO heterojunctions for efficient Cr(VI) reduction and E. coli inactivation under visible light irradiation

Abstract

The development of multifunctional photocatalysts with high efficiency is vital advancing for environmental remediation and sustainable water treatment. In this work, a BS-based semiconductor heterojunction was fabricated by coupling BS with ZnO through a facile hydrothermal approach. The resulting BS@ZnO nanocomposites exhibited a unique echinoid-like morphology and were comprehensively characterized to assess their structural, optical, and surface properties. For the first time, the BS@ZnO was applied to dual photocatalytic functions, Cr(VI) reduction and Escherichia coli inactivation under visible-light irradiation. The optimized BS@ZnO-10 % composite demonstrated outstanding performance, achieving 98.9 % Cr(VI) reduction in 100 min and 97.05 % bacterial inactivation in just 75 min, significantly surpassing the activity of previously reported Bi-based photocatalysts. The enhanced photocatalytic efficiency is attributed to improved light absorption, efficient charge separation, and an increased specific surface area, 4.8 times greater than pure ZnO. Mott-Schottky analysis confirmed that the interface forms an n–n type Z-scheme heterojunction, enabling effective charge transfer while preserving strong redox ability. These results highlight the synergistic effects between BS and ZnO and establish BS@ZnO as a promising multifunctional photocatalyst for integrated wastewater treatment.