Yujia Yan,Min Yang,Cunjin Wang,Enzhou Liu,Xiaoyun Hu,Jun Fan
Defect–rich zinc sulfide (ZnS, ZS) was successfully synthesized by the slow release of S source from glutathione (GSH) to coordinate with Zn 2+ at high temperature. Based on this, a novel ZnS/g–C 3 N 4 (ZSCN) heterojunction with high catalytic activity was fabricated through facile in–situ hydrothermal method . The removal rates of Rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and Cr 6+ for ZSCN–0.05 with the highest catalytic activity under full–spectrum illumination were 13.0, 53.2, 2.0 and 11.6 times of g–C 3 N 4 (CN), and 3.6, 14.8, 1.2 and 3.9 times of ZS, respectively. While, under visible–light illumination, ZSCN–0.075 exhibited the best photodegradation performance for RhB, and the degradation rate was 5.2 and 19.3 times to CN and ZS, respectively. The enhanced photocatalytic activity of ZSCN heterojunction could be attributed to the synergistic effect between CN and ZS: ZS with defect-rich enhanced the absorption intensity of ZSCN in the ultraviolet, and CN broaden the spectral response range of ZSCN. Moreover photoluminescence spectrum confirmed that the formation of ZSCN heterojunction could effectively inhibit the recombination of photogenerated electrons and holes, and accelerate the electron transfer at its interface.
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 Co 9 S 8 @defective ZnS/g-C 3 N 4 (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 ( 1 O 2 ) in multi-pollutants environment. Further tests of intermediates and reusability indicated its potential for the high-efficient treatment of multiple pollution systems.
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