Efficient hollow cubic Co9S8@defective ZnS/g-C3N4 for multi-pollutants removal via cascade Z-scheme heterojunction

Abstract

Multi-pollutants environment coexisted organic and inorganic pollutants has become a common phenomenon, seriously affecting water biodiversity and human water security. Currently, the removal of organic and inorganic pollutants by photocatalysis are mostly in own single-pollutant environment, not in multi-pollutants system, where the common photocatalysts cannot achieve efficiently charge separate and transfer with low reactive oxygen species (ROS) efficiency. Herein, we constructed an efficient cascaded Z-scheme heterojunction Co9S8 @defective ZnS/g-C3N4 (C@DZ/N) composed of defective engineering in hollow nanocubes, which achieved excellent photodegradation activity (98.93 % for ciprofloxacin (CIP) and 97.18 % for Cr(VI) at 90 min) in multi-pollutants environment, significantly higher than the hollow cubic with Z-scheme heterojunction in single-pollutant environment (98.07 % for CIP and 98.72 % for Cr(VI) at 140 min). Defective ZnS acts as the core for direct charge transfer and separation to form a unique cascaded Z-scheme heterojunction system that blocks the type II charge transfer pathway to achieve ultra-efficient charge transfer. Furthermore, the structural characterization and ROS experimental results based on multi-pollutants models show that the cascade Z-scheme system greatly facilitates the ROS release kinetics and further leads to more electron-deficient cubic surfaces while increase the directional conversion to singlet oxygen (1O2) in multi-pollutants environment. Further tests of intermediates and reusability indicated its potential for the high-efficient treatment of multiple pollution systems.