Simultaneous water sterilization and photodegradation of malachite green based on Z-scheme heterojunction of bimetallic sulfide and zinc phthalocyanine

Abstract

Multifunctional Z-scheme heterojunction has emerged as an alternative to achieve the photocatalytic sterilization and photodegradation of organic pollutants. Herein, a novel Z-scheme heterojunction based on bimetallic sulfide and zinc phthalocyanine (ZnPc) was established as a robust bifunctional photocatalyst to sterilize and degrade malachite green (MG) contained in wastewater. Ultrathin Ag2S/MoS2 nanosheets were vertically grown over ZnPc nanorods in situ through hydrothermal method, generating a Z-scheme heterojunction (denoted as Ag2S/MoS2@ZnPc). Results showed enhanced photo-adsorption within full spectrum range, narrowed band gap, and modulated electron structure of metal sites of the heterojunction were achieved via the synergistic effect of interface and defect engineering. The Z-scheme Ag2S/MoS2@ZnPc heterojunction demonstrated a boost in the production of reactive oxygen species, superior photothermal effect, high self-supplying H2O2 ability (737.72 μmol g−1h−1), and the controllable release behavior of Ag+ ions under near-infrared (NIR) light irradiation. Almost 100 % bacteria in wastewater were eliminated by this Z-scheme heterojunction owing to the multimodal antibacterial mechanism under NIR illumination (808 nm, 1.0 W cm−2). Moreover, the Ag2S/MoS2@ZnPc heterojunction exhibited high MG absorption capability in the dark (64.95 mg g−1 at 30 min) and enhanced photodegradation ability under ultraviolet–visible light irradiation (96.3 % at 100 min). The practical experiments unveiled that the developed multifunctional photocatalyst could be employed to treat the wastewater containing pathogenic bacteria and organic pollutants via the thorough sterilization and photodegradation/adsorption of MG.